Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3582 insertions, 0 deletions

diff --git a/media/libcubeb/src/cubeb_wasapi.cpp b/media/libcubeb/src/cubeb_wasapi.cpp
new file mode 100644
index 0000000000..711836a0f4
--- /dev/null
+++ b/media/libcubeb/src/cubeb_wasapi.cpp
@@ -0,0 +1,3582 @@
+/*
+ * Copyright © 2013 Mozilla Foundation
+ *
+ * This program is made available under an ISC-style license.  See the
+ * accompanying file LICENSE for details.
+ */
+#define _WIN32_WINNT 0x0603
+#define NOMINMAX
+
+#include <algorithm>
+#include <atomic>
+#include <audioclient.h>
+#include <avrt.h>
+#include <cmath>
+#include <devicetopology.h>
+#include <initguid.h>
+#include <limits>
+#include <memory>
+#include <mmdeviceapi.h>
+#include <process.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <vector>
+#include <windef.h>
+#include <windows.h>
+/* clang-format off */
+/* These need to be included after windows.h */
+#include <mmsystem.h>
+/* clang-format on */
+
+#include "cubeb-internal.h"
+#include "cubeb/cubeb.h"
+#include "cubeb_mixer.h"
+#include "cubeb_resampler.h"
+#include "cubeb_strings.h"
+#include "cubeb_tracing.h"
+#include "cubeb_utils.h"
+
+// Windows 10 exposes the IAudioClient3 interface to create low-latency streams.
+// Copy the interface definition from audioclient.h here to make the code
+// simpler and so that we can still access IAudioClient3 via COM if cubeb was
+// compiled against an older SDK.
+#ifndef __IAudioClient3_INTERFACE_DEFINED__
+#define __IAudioClient3_INTERFACE_DEFINED__
+MIDL_INTERFACE("7ED4EE07-8E67-4CD4-8C1A-2B7A5987AD42")
+IAudioClient3 : public IAudioClient
+{
+public:
+  virtual HRESULT STDMETHODCALLTYPE GetSharedModeEnginePeriod(
+      /* [annotation][in] */
+      _In_ const WAVEFORMATEX * pFormat,
+      /* [annotation][out] */
+      _Out_ UINT32 * pDefaultPeriodInFrames,
+      /* [annotation][out] */
+      _Out_ UINT32 * pFundamentalPeriodInFrames,
+      /* [annotation][out] */
+      _Out_ UINT32 * pMinPeriodInFrames,
+      /* [annotation][out] */
+      _Out_ UINT32 * pMaxPeriodInFrames) = 0;
+
+  virtual HRESULT STDMETHODCALLTYPE GetCurrentSharedModeEnginePeriod(
+      /* [unique][annotation][out] */
+      _Out_ WAVEFORMATEX * *ppFormat,
+      /* [annotation][out] */
+      _Out_ UINT32 * pCurrentPeriodInFrames) = 0;
+
+  virtual HRESULT STDMETHODCALLTYPE InitializeSharedAudioStream(
+      /* [annotation][in] */
+      _In_ DWORD StreamFlags,
+      /* [annotation][in] */
+      _In_ UINT32 PeriodInFrames,
+      /* [annotation][in] */
+      _In_ const WAVEFORMATEX * pFormat,
+      /* [annotation][in] */
+      _In_opt_ LPCGUID AudioSessionGuid) = 0;
+};
+#ifdef __CRT_UUID_DECL
+// Required for MinGW
+__CRT_UUID_DECL(IAudioClient3, 0x7ED4EE07, 0x8E67, 0x4CD4, 0x8C, 0x1A, 0x2B,
+                0x7A, 0x59, 0x87, 0xAD, 0x42)
+#endif
+#endif
+// Copied from audioclient.h in the Windows 10 SDK
+#ifndef AUDCLNT_E_ENGINE_PERIODICITY_LOCKED
+#define AUDCLNT_E_ENGINE_PERIODICITY_LOCKED AUDCLNT_ERR(0x028)
+#endif
+
+#ifndef PKEY_Device_FriendlyName
+DEFINE_PROPERTYKEY(PKEY_Device_FriendlyName, 0xa45c254e, 0xdf1c, 0x4efd, 0x80,
+                   0x20, 0x67, 0xd1, 0x46, 0xa8, 0x50, 0xe0,
+                   14); // DEVPROP_TYPE_STRING
+#endif
+#ifndef PKEY_Device_InstanceId
+DEFINE_PROPERTYKEY(PKEY_Device_InstanceId, 0x78c34fc8, 0x104a, 0x4aca, 0x9e,
+                   0xa4, 0x52, 0x4d, 0x52, 0x99, 0x6e, 0x57,
+                   0x00000100); //    VT_LPWSTR
+#endif
+
+namespace {
+
+const int64_t LATENCY_NOT_AVAILABLE_YET = -1;
+
+const DWORD DEVICE_CHANGE_DEBOUNCE_MS = 250;
+
+struct com_heap_ptr_deleter {
+  void operator()(void * ptr) const noexcept { CoTaskMemFree(ptr); }
+};
+
+template <typename T>
+using com_heap_ptr = std::unique_ptr<T, com_heap_ptr_deleter>;
+
+template <typename T, size_t N>
+constexpr size_t
+ARRAY_LENGTH(T (&)[N])
+{
+  return N;
+}
+
+template <typename T> class no_addref_release : public T {
+  ULONG STDMETHODCALLTYPE AddRef() = 0;
+  ULONG STDMETHODCALLTYPE Release() = 0;
+};
+
+template <typename T> class com_ptr {
+public:
+  com_ptr() noexcept = default;
+
+  com_ptr(com_ptr const & other) noexcept = delete;
+  com_ptr & operator=(com_ptr const & other) noexcept = delete;
+  T ** operator&() const noexcept = delete;
+
+  ~com_ptr() noexcept { release(); }
+
+  com_ptr(com_ptr && other) noexcept : ptr(other.ptr) { other.ptr = nullptr; }
+
+  com_ptr & operator=(com_ptr && other) noexcept
+  {
+    if (ptr != other.ptr) {
+      release();
+      ptr = other.ptr;
+      other.ptr = nullptr;
+    }
+    return *this;
+  }
+
+  explicit operator bool() const noexcept { return nullptr != ptr; }
+
+  no_addref_release<T> * operator->() const noexcept
+  {
+    return static_cast<no_addref_release<T> *>(ptr);
+  }
+
+  T * get() const noexcept { return ptr; }
+
+  T ** receive() noexcept
+  {
+    XASSERT(ptr == nullptr);
+    return &ptr;
+  }
+
+  void ** receive_vpp() noexcept
+  {
+    return reinterpret_cast<void **>(receive());
+  }
+
+  com_ptr & operator=(std::nullptr_t) noexcept
+  {
+    release();
+    return *this;
+  }
+
+  void reset(T * p = nullptr) noexcept
+  {
+    release();
+    ptr = p;
+  }
+
+private:
+  void release() noexcept
+  {
+    T * temp = ptr;
+
+    if (temp) {
+      ptr = nullptr;
+      temp->Release();
+    }
+  }
+
+  T * ptr = nullptr;
+};
+
+LONG
+wasapi_stream_add_ref(cubeb_stream * stm);
+LONG
+wasapi_stream_release(cubeb_stream * stm);
+
+struct auto_stream_ref {
+  auto_stream_ref(cubeb_stream * stm_) : stm(stm_)
+  {
+    wasapi_stream_add_ref(stm);
+  }
+  ~auto_stream_ref() { wasapi_stream_release(stm); }
+  cubeb_stream * stm;
+};
+
+extern cubeb_ops const wasapi_ops;
+
+static com_heap_ptr<wchar_t>
+wasapi_get_default_device_id(EDataFlow flow, ERole role,
+                             IMMDeviceEnumerator * enumerator);
+
+struct wasapi_default_devices {
+  wasapi_default_devices(IMMDeviceEnumerator * enumerator)
+      : render_console_id(
+            wasapi_get_default_device_id(eRender, eConsole, enumerator)),
+        render_comms_id(
+            wasapi_get_default_device_id(eRender, eCommunications, enumerator)),
+        capture_console_id(
+            wasapi_get_default_device_id(eCapture, eConsole, enumerator)),
+        capture_comms_id(
+            wasapi_get_default_device_id(eCapture, eCommunications, enumerator))
+  {
+  }
+
+  bool is_default(EDataFlow flow, ERole role, wchar_t const * id)
+  {
+    wchar_t const * default_id = nullptr;
+    if (flow == eRender && role == eConsole) {
+      default_id = this->render_console_id.get();
+    } else if (flow == eRender && role == eCommunications) {
+      default_id = this->render_comms_id.get();
+    } else if (flow == eCapture && role == eConsole) {
+      default_id = this->capture_console_id.get();
+    } else if (flow == eCapture && role == eCommunications) {
+      default_id = this->capture_comms_id.get();
+    }
+
+    return default_id && wcscmp(id, default_id) == 0;
+  }
+
+private:
+  com_heap_ptr<wchar_t> render_console_id;
+  com_heap_ptr<wchar_t> render_comms_id;
+  com_heap_ptr<wchar_t> capture_console_id;
+  com_heap_ptr<wchar_t> capture_comms_id;
+};
+
+struct AutoRegisterThread {
+  AutoRegisterThread(const char * name) { CUBEB_REGISTER_THREAD(name); }
+  ~AutoRegisterThread() { CUBEB_UNREGISTER_THREAD(); }
+};
+
+int
+wasapi_stream_stop(cubeb_stream * stm);
+int
+wasapi_stream_start(cubeb_stream * stm);
+void
+close_wasapi_stream(cubeb_stream * stm);
+int
+setup_wasapi_stream(cubeb_stream * stm);
+ERole
+pref_to_role(cubeb_stream_prefs param);
+int
+wasapi_create_device(cubeb * ctx, cubeb_device_info & ret,
+                     IMMDeviceEnumerator * enumerator, IMMDevice * dev,
+                     wasapi_default_devices * defaults);
+void
+wasapi_destroy_device(cubeb_device_info * device_info);
+static int
+wasapi_enumerate_devices_internal(cubeb * context, cubeb_device_type type,
+                                  cubeb_device_collection * out,
+                                  DWORD state_mask);
+static int
+wasapi_device_collection_destroy(cubeb * ctx,
+                                 cubeb_device_collection * collection);
+static char const *
+wstr_to_utf8(wchar_t const * str);
+static std::unique_ptr<wchar_t const[]>
+utf8_to_wstr(char const * str);
+
+} // namespace
+
+class wasapi_collection_notification_client;
+class monitor_device_notifications;
+
+struct cubeb {
+  cubeb_ops const * ops = &wasapi_ops;
+  owned_critical_section lock;
+  cubeb_strings * device_ids;
+  /* Device enumerator to get notifications when the
+     device collection change. */
+  com_ptr<IMMDeviceEnumerator> device_collection_enumerator;
+  com_ptr<wasapi_collection_notification_client> collection_notification_client;
+  /* Collection changed for input (capture) devices. */
+  cubeb_device_collection_changed_callback input_collection_changed_callback =
+      nullptr;
+  void * input_collection_changed_user_ptr = nullptr;
+  /* Collection changed for output (render) devices. */
+  cubeb_device_collection_changed_callback output_collection_changed_callback =
+      nullptr;
+  void * output_collection_changed_user_ptr = nullptr;
+  UINT64 performance_counter_frequency;
+};
+
+class wasapi_endpoint_notification_client;
+
+/* We have three possible callbacks we can use with a stream:
+ * - input only
+ * - output only
+ * - synchronized input and output
+ *
+ * Returns true when we should continue to play, false otherwise.
+ */
+typedef bool (*wasapi_refill_callback)(cubeb_stream * stm);
+
+struct cubeb_stream {
+  /* Note: Must match cubeb_stream layout in cubeb.c. */
+  cubeb * context = nullptr;
+  void * user_ptr = nullptr;
+  /**/
+
+  /* Mixer pameters. We need to convert the input stream to this
+     samplerate/channel layout, as WASAPI does not resample nor upmix
+     itself. */
+  cubeb_stream_params input_mix_params = {CUBEB_SAMPLE_FLOAT32NE, 0, 0,
+                                          CUBEB_LAYOUT_UNDEFINED,
+                                          CUBEB_STREAM_PREF_NONE};
+  cubeb_stream_params output_mix_params = {CUBEB_SAMPLE_FLOAT32NE, 0, 0,
+                                           CUBEB_LAYOUT_UNDEFINED,
+                                           CUBEB_STREAM_PREF_NONE};
+  /* Stream parameters. This is what the client requested,
+   * and what will be presented in the callback. */
+  cubeb_stream_params input_stream_params = {CUBEB_SAMPLE_FLOAT32NE, 0, 0,
+                                             CUBEB_LAYOUT_UNDEFINED,
+                                             CUBEB_STREAM_PREF_NONE};
+  cubeb_stream_params output_stream_params = {CUBEB_SAMPLE_FLOAT32NE, 0, 0,
+                                              CUBEB_LAYOUT_UNDEFINED,
+                                              CUBEB_STREAM_PREF_NONE};
+  /* A MMDevice role for this stream: either communication or console here. */
+  ERole role;
+  /* True if this stream will transport voice-data. */
+  bool voice;
+  /* True if the input device of this stream is using bluetooth handsfree. */
+  bool input_bluetooth_handsfree;
+  /* The input and output device, or NULL for default. */
+  std::unique_ptr<const wchar_t[]> input_device_id;
+  std::unique_ptr<const wchar_t[]> output_device_id;
+  com_ptr<IMMDevice> input_device;
+  com_ptr<IMMDevice> output_device;
+  /* The latency initially requested for this stream, in frames. */
+  unsigned latency = 0;
+  cubeb_state_callback state_callback = nullptr;
+  cubeb_data_callback data_callback = nullptr;
+  wasapi_refill_callback refill_callback = nullptr;
+  /* True when a loopback device is requested with no output device. In this
+     case a dummy output device is opened to drive the loopback, but should not
+     be exposed. */
+  bool has_dummy_output = false;
+  /* Lifetime considerations:
+     - client, render_client, audio_clock and audio_stream_volume are interface
+       pointer to the IAudioClient.
+     - The lifetime for device_enumerator and notification_client, resampler,
+       mix_buffer are the same as the cubeb_stream instance. */
+
+  /* Main handle on the WASAPI stream. */
+  com_ptr<IAudioClient> output_client;
+  /* Interface pointer to use the event-driven interface. */
+  com_ptr<IAudioRenderClient> render_client;
+#ifdef CUBEB_WASAPI_USE_IAUDIOSTREAMVOLUME
+  /* Interface pointer to use the volume facilities. */
+  com_ptr<IAudioStreamVolume> audio_stream_volume;
+#endif
+  /* Interface pointer to use the stream audio clock. */
+  com_ptr<IAudioClock> audio_clock;
+  /* Frames written to the stream since it was opened. Reset on device
+     change. Uses mix_params.rate. */
+  UINT64 frames_written = 0;
+  /* Frames written to the (logical) stream since it was first
+     created. Updated on device change. Uses stream_params.rate. */
+  UINT64 total_frames_written = 0;
+  /* Last valid reported stream position.  Used to ensure the position
+     reported by stream_get_position increases monotonically. */
+  UINT64 prev_position = 0;
+  /* Device enumerator to be able to be notified when the default
+     device change. */
+  com_ptr<IMMDeviceEnumerator> device_enumerator;
+  /* Device notification client, to be able to be notified when the default
+     audio device changes and route the audio to the new default audio output
+     device */
+  com_ptr<wasapi_endpoint_notification_client> notification_client;
+  /* Main andle to the WASAPI capture stream. */
+  com_ptr<IAudioClient> input_client;
+  /* Interface to use the event driven capture interface */
+  com_ptr<IAudioCaptureClient> capture_client;
+  /* This event is set by the stream_destroy function, so the render loop can
+     exit properly. */
+  HANDLE shutdown_event = 0;
+  /* Set by OnDefaultDeviceChanged when a stream reconfiguration is required.
+     The reconfiguration is handled by the render loop thread. */
+  HANDLE reconfigure_event = 0;
+  /* This is set by WASAPI when we should refill the stream. */
+  HANDLE refill_event = 0;
+  /* This is set by WASAPI when we should read from the input stream. In
+   * practice, we read from the input stream in the output callback, so
+   * this is not used, but it is necessary to start getting input data. */
+  HANDLE input_available_event = 0;
+  /* Each cubeb_stream has its own thread. */
+  HANDLE thread = 0;
+  /* The lock protects all members that are touched by the render thread or
+     change during a device reset, including: audio_clock, audio_stream_volume,
+     client, frames_written, mix_params, total_frames_written, prev_position. */
+  owned_critical_section stream_reset_lock;
+  /* Maximum number of frames that can be passed down in a callback. */
+  uint32_t input_buffer_frame_count = 0;
+  /* Maximum number of frames that can be requested in a callback. */
+  uint32_t output_buffer_frame_count = 0;
+  /* Resampler instance. Resampling will only happen if necessary. */
+  std::unique_ptr<cubeb_resampler, decltype(&cubeb_resampler_destroy)>
+      resampler = {nullptr, cubeb_resampler_destroy};
+  /* Mixer interfaces */
+  std::unique_ptr<cubeb_mixer, decltype(&cubeb_mixer_destroy)> output_mixer = {
+      nullptr, cubeb_mixer_destroy};
+  std::unique_ptr<cubeb_mixer, decltype(&cubeb_mixer_destroy)> input_mixer = {
+      nullptr, cubeb_mixer_destroy};
+  /* A buffer for up/down mixing multi-channel audio output. */
+  std::vector<BYTE> mix_buffer;
+  /* WASAPI input works in "packets". We re-linearize the audio packets
+   * into this buffer before handing it to the resampler. */
+  std::unique_ptr<auto_array_wrapper> linear_input_buffer;
+  /* Bytes per sample. This multiplied by the number of channels is the number
+   * of bytes per frame. */
+  size_t bytes_per_sample = 0;
+  /* WAVEFORMATEXTENSIBLE sub-format: either PCM or float. */
+  GUID waveformatextensible_sub_format = GUID_NULL;
+  /* Stream volume.  Set via stream_set_volume and used to reset volume on
+     device changes. */
+  float volume = 1.0;
+  /* True if the stream is draining. */
+  bool draining = false;
+  /* This needs an active audio input stream to be known, and is updated in the
+   * first audio input callback. */
+  std::atomic<int64_t> input_latency_hns{LATENCY_NOT_AVAILABLE_YET};
+  /* Those attributes count the number of frames requested (resp. received) by
+  the OS, to be able to detect drifts. This is only used for logging for now. */
+  size_t total_input_frames = 0;
+  size_t total_output_frames = 0;
+  /* This is set by the render loop thread once it has obtained a reference to
+   * COM and this stream object. */
+  HANDLE thread_ready_event = 0;
+  /* Keep a ref count on this stream object. After both stream_destroy has been
+   * called and the render loop thread has exited, destroy this stream object.
+   */
+  LONG ref_count = 0;
+
+  /* True if the stream is active, false if inactive. */
+  bool active = false;
+};
+
+class monitor_device_notifications {
+public:
+  monitor_device_notifications(cubeb * context) : cubeb_context(context)
+  {
+    create_thread();
+  }
+
+  ~monitor_device_notifications()
+  {
+    SetEvent(begin_shutdown);
+    WaitForSingleObject(shutdown_complete, INFINITE);
+    CloseHandle(thread);
+
+    CloseHandle(input_changed);
+    CloseHandle(output_changed);
+    CloseHandle(begin_shutdown);
+    CloseHandle(shutdown_complete);
+  }
+
+  void notify(EDataFlow flow)
+  {
+    XASSERT(cubeb_context);
+    if (flow == eCapture && cubeb_context->input_collection_changed_callback) {
+      bool res = SetEvent(input_changed);
+      if (!res) {
+        LOG("Failed to set input changed event");
+      }
+      return;
+    }
+    if (flow == eRender && cubeb_context->output_collection_changed_callback) {
+      bool res = SetEvent(output_changed);
+      if (!res) {
+        LOG("Failed to set output changed event");
+      }
+    }
+  }
+
+private:
+  static unsigned int __stdcall thread_proc(LPVOID args)
+  {
+    AutoRegisterThread raii("WASAPI device notification thread");
+    XASSERT(args);
+    auto mdn = static_cast<monitor_device_notifications *>(args);
+    mdn->notification_thread_loop();
+    SetEvent(mdn->shutdown_complete);
+    return 0;
+  }
+
+  void notification_thread_loop()
+  {
+    struct auto_com {
+      auto_com()
+      {
+        HRESULT hr = CoInitializeEx(nullptr, COINIT_MULTITHREADED);
+        XASSERT(SUCCEEDED(hr));
+      }
+      ~auto_com() { CoUninitialize(); }
+    } com;
+
+    HANDLE wait_array[3] = {
+        input_changed,
+        output_changed,
+        begin_shutdown,
+    };
+
+    while (true) {
+      Sleep(200);
+
+      DWORD wait_result = WaitForMultipleObjects(ARRAY_LENGTH(wait_array),
+                                                 wait_array, FALSE, INFINITE);
+      if (wait_result == WAIT_OBJECT_0) { // input changed
+        cubeb_context->input_collection_changed_callback(
+            cubeb_context, cubeb_context->input_collection_changed_user_ptr);
+      } else if (wait_result == WAIT_OBJECT_0 + 1) { // output changed
+        cubeb_context->output_collection_changed_callback(
+            cubeb_context, cubeb_context->output_collection_changed_user_ptr);
+      } else if (wait_result == WAIT_OBJECT_0 + 2) { // shutdown
+        break;
+      } else {
+        LOG("Unexpected result %lu", wait_result);
+      }
+    } // loop
+  }
+
+  void create_thread()
+  {
+    output_changed = CreateEvent(nullptr, 0, 0, nullptr);
+    if (!output_changed) {
+      LOG("Failed to create output changed event.");
+      return;
+    }
+
+    input_changed = CreateEvent(nullptr, 0, 0, nullptr);
+    if (!input_changed) {
+      LOG("Failed to create input changed event.");
+      return;
+    }
+
+    begin_shutdown = CreateEvent(nullptr, 0, 0, nullptr);
+    if (!begin_shutdown) {
+      LOG("Failed to create begin_shutdown event.");
+      return;
+    }
+
+    shutdown_complete = CreateEvent(nullptr, 0, 0, nullptr);
+    if (!shutdown_complete) {
+      LOG("Failed to create shutdown_complete event.");
+      return;
+    }
+
+    thread = (HANDLE)_beginthreadex(nullptr, 256 * 1024, thread_proc, this,
+                                    STACK_SIZE_PARAM_IS_A_RESERVATION, nullptr);
+    if (!thread) {
+      LOG("Failed to create thread.");
+      return;
+    }
+  }
+
+  HANDLE thread = INVALID_HANDLE_VALUE;
+  HANDLE output_changed = INVALID_HANDLE_VALUE;
+  HANDLE input_changed = INVALID_HANDLE_VALUE;
+  HANDLE begin_shutdown = INVALID_HANDLE_VALUE;
+  HANDLE shutdown_complete = INVALID_HANDLE_VALUE;
+
+  cubeb * cubeb_context = nullptr;
+};
+
+class wasapi_collection_notification_client : public IMMNotificationClient {
+public:
+  /* The implementation of MSCOM was copied from MSDN. */
+  ULONG STDMETHODCALLTYPE AddRef() { return InterlockedIncrement(&ref_count); }
+
+  ULONG STDMETHODCALLTYPE Release()
+  {
+    ULONG ulRef = InterlockedDecrement(&ref_count);
+    if (0 == ulRef) {
+      delete this;
+    }
+    return ulRef;
+  }
+
+  HRESULT STDMETHODCALLTYPE QueryInterface(REFIID riid, VOID ** ppvInterface)
+  {
+    if (__uuidof(IUnknown) == riid) {
+      AddRef();
+      *ppvInterface = (IUnknown *)this;
+    } else if (__uuidof(IMMNotificationClient) == riid) {
+      AddRef();
+      *ppvInterface = (IMMNotificationClient *)this;
+    } else {
+      *ppvInterface = NULL;
+      return E_NOINTERFACE;
+    }
+    return S_OK;
+  }
+
+  wasapi_collection_notification_client(cubeb * context)
+      : ref_count(1), cubeb_context(context), monitor_notifications(context)
+  {
+    XASSERT(cubeb_context);
+  }
+
+  virtual ~wasapi_collection_notification_client() {}
+
+  HRESULT STDMETHODCALLTYPE OnDefaultDeviceChanged(EDataFlow flow, ERole role,
+                                                   LPCWSTR device_id)
+  {
+    LOG("collection: Audio device default changed, id = %S.", device_id);
+    return S_OK;
+  }
+
+  /* The remaining methods are not implemented, they simply log when called (if
+     log is enabled), for debugging. */
+  HRESULT STDMETHODCALLTYPE OnDeviceAdded(LPCWSTR device_id)
+  {
+    LOG("collection: Audio device added.");
+    return S_OK;
+  };
+
+  HRESULT STDMETHODCALLTYPE OnDeviceRemoved(LPCWSTR device_id)
+  {
+    LOG("collection: Audio device removed.");
+    return S_OK;
+  }
+
+  HRESULT STDMETHODCALLTYPE OnDeviceStateChanged(LPCWSTR device_id,
+                                                 DWORD new_state)
+  {
+    XASSERT(cubeb_context->output_collection_changed_callback ||
+            cubeb_context->input_collection_changed_callback);
+    LOG("collection: Audio device state changed, id = %S, state = %lu.",
+        device_id, new_state);
+    EDataFlow flow;
+    HRESULT hr = GetDataFlow(device_id, &flow);
+    if (FAILED(hr)) {
+      return hr;
+    }
+    monitor_notifications.notify(flow);
+    return S_OK;
+  }
+
+  HRESULT STDMETHODCALLTYPE OnPropertyValueChanged(LPCWSTR device_id,
+                                                   const PROPERTYKEY key)
+  {
+    // Audio device property value changed.
+    return S_OK;
+  }
+
+private:
+  HRESULT GetDataFlow(LPCWSTR device_id, EDataFlow * flow)
+  {
+    com_ptr<IMMDevice> device;
+    com_ptr<IMMEndpoint> endpoint;
+
+    HRESULT hr = cubeb_context->device_collection_enumerator->GetDevice(
+        device_id, device.receive());
+    if (FAILED(hr)) {
+      LOG("collection: Could not get device: %lx", hr);
+      return hr;
+    }
+
+    hr = device->QueryInterface(IID_PPV_ARGS(endpoint.receive()));
+    if (FAILED(hr)) {
+      LOG("collection: Could not get endpoint: %lx", hr);
+      return hr;
+    }
+
+    return endpoint->GetDataFlow(flow);
+  }
+
+  /* refcount for this instance, necessary to implement MSCOM semantics. */
+  LONG ref_count;
+
+  cubeb * cubeb_context = nullptr;
+  monitor_device_notifications monitor_notifications;
+};
+
+class wasapi_endpoint_notification_client : public IMMNotificationClient {
+public:
+  /* The implementation of MSCOM was copied from MSDN. */
+  ULONG STDMETHODCALLTYPE AddRef() { return InterlockedIncrement(&ref_count); }
+
+  ULONG STDMETHODCALLTYPE Release()
+  {
+    ULONG ulRef = InterlockedDecrement(&ref_count);
+    if (0 == ulRef) {
+      delete this;
+    }
+    return ulRef;
+  }
+
+  HRESULT STDMETHODCALLTYPE QueryInterface(REFIID riid, VOID ** ppvInterface)
+  {
+    if (__uuidof(IUnknown) == riid) {
+      AddRef();
+      *ppvInterface = (IUnknown *)this;
+    } else if (__uuidof(IMMNotificationClient) == riid) {
+      AddRef();
+      *ppvInterface = (IMMNotificationClient *)this;
+    } else {
+      *ppvInterface = NULL;
+      return E_NOINTERFACE;
+    }
+    return S_OK;
+  }
+
+  wasapi_endpoint_notification_client(HANDLE event, ERole role)
+      : ref_count(1), reconfigure_event(event), role(role),
+        last_device_change(timeGetTime())
+  {
+  }
+
+  virtual ~wasapi_endpoint_notification_client() {}
+
+  HRESULT STDMETHODCALLTYPE OnDefaultDeviceChanged(EDataFlow flow, ERole role,
+                                                   LPCWSTR device_id)
+  {
+    LOG("endpoint: Audio device default changed flow=%d role=%d "
+        "new_device_id=%ws.",
+        flow, role, device_id);
+
+    /* we only support a single stream type for now. */
+    if (flow != eRender || role != this->role) {
+      return S_OK;
+    }
+
+    DWORD last_change_ms = timeGetTime() - last_device_change;
+    bool same_device = default_device_id && device_id &&
+                       wcscmp(default_device_id.get(), device_id) == 0;
+    LOG("endpoint: Audio device default changed last_change=%u same_device=%d",
+        last_change_ms, same_device);
+    if (last_change_ms > DEVICE_CHANGE_DEBOUNCE_MS || !same_device) {
+      if (device_id) {
+        default_device_id.reset(_wcsdup(device_id));
+      } else {
+        default_device_id.reset();
+      }
+      BOOL ok = SetEvent(reconfigure_event);
+      LOG("endpoint: Audio device default changed: trigger reconfig");
+      if (!ok) {
+        LOG("endpoint: SetEvent on reconfigure_event failed: %lx",
+            GetLastError());
+      }
+    }
+
+    return S_OK;
+  }
+
+  /* The remaining methods are not implemented, they simply log when called (if
+     log is enabled), for debugging. */
+  HRESULT STDMETHODCALLTYPE OnDeviceAdded(LPCWSTR device_id)
+  {
+    LOG("endpoint: Audio device added.");
+    return S_OK;
+  };
+
+  HRESULT STDMETHODCALLTYPE OnDeviceRemoved(LPCWSTR device_id)
+  {
+    LOG("endpoint: Audio device removed.");
+    return S_OK;
+  }
+
+  HRESULT STDMETHODCALLTYPE OnDeviceStateChanged(LPCWSTR device_id,
+                                                 DWORD new_state)
+  {
+    LOG("endpoint: Audio device state changed.");
+    return S_OK;
+  }
+
+  HRESULT STDMETHODCALLTYPE OnPropertyValueChanged(LPCWSTR device_id,
+                                                   const PROPERTYKEY key)
+  {
+    // Audio device property value changed.
+    return S_OK;
+  }
+
+private:
+  /* refcount for this instance, necessary to implement MSCOM semantics. */
+  LONG ref_count;
+  HANDLE reconfigure_event;
+  ERole role;
+  std::unique_ptr<const wchar_t[]> default_device_id;
+  DWORD last_device_change;
+};
+
+namespace {
+
+long
+wasapi_data_callback(cubeb_stream * stm, void * user_ptr,
+                     void const * input_buffer, void * output_buffer,
+                     long nframes)
+{
+  return stm->data_callback(stm, user_ptr, input_buffer, output_buffer,
+                            nframes);
+}
+
+void
+wasapi_state_callback(cubeb_stream * stm, void * user_ptr, cubeb_state state)
+{
+  return stm->state_callback(stm, user_ptr, state);
+}
+
+char const *
+intern_device_id(cubeb * ctx, wchar_t const * id)
+{
+  XASSERT(id);
+
+  auto_lock lock(ctx->lock);
+
+  char const * tmp = wstr_to_utf8(id);
+  if (!tmp) {
+    return nullptr;
+  }
+
+  char const * interned = cubeb_strings_intern(ctx->device_ids, tmp);
+
+  free((void *)tmp);
+
+  return interned;
+}
+
+bool
+has_input(cubeb_stream * stm)
+{
+  return stm->input_stream_params.rate != 0;
+}
+
+bool
+has_output(cubeb_stream * stm)
+{
+  return stm->output_stream_params.rate != 0;
+}
+
+double
+stream_to_mix_samplerate_ratio(cubeb_stream_params & stream,
+                               cubeb_stream_params & mixer)
+{
+  return double(stream.rate) / mixer.rate;
+}
+
+/* Convert the channel layout into the corresponding KSAUDIO_CHANNEL_CONFIG.
+   See more:
+   https://msdn.microsoft.com/en-us/library/windows/hardware/ff537083(v=vs.85).aspx
+ */
+
+cubeb_channel_layout
+mask_to_channel_layout(WAVEFORMATEX const * fmt)
+{
+  cubeb_channel_layout mask = 0;
+
+  if (fmt->wFormatTag == WAVE_FORMAT_EXTENSIBLE) {
+    WAVEFORMATEXTENSIBLE const * ext =
+        reinterpret_cast<WAVEFORMATEXTENSIBLE const *>(fmt);
+    mask = ext->dwChannelMask;
+  } else if (fmt->wFormatTag == WAVE_FORMAT_PCM ||
+             fmt->wFormatTag == WAVE_FORMAT_IEEE_FLOAT) {
+    if (fmt->nChannels == 1) {
+      mask = CHANNEL_FRONT_CENTER;
+    } else if (fmt->nChannels == 2) {
+      mask = CHANNEL_FRONT_LEFT | CHANNEL_FRONT_RIGHT;
+    }
+  }
+  return mask;
+}
+
+uint32_t
+get_rate(cubeb_stream * stm)
+{
+  return has_input(stm) ? stm->input_stream_params.rate
+                        : stm->output_stream_params.rate;
+}
+
+uint32_t
+hns_to_frames(uint32_t rate, REFERENCE_TIME hns)
+{
+  return std::ceil((hns - 1) / 10000000.0 * rate);
+}
+
+uint32_t
+hns_to_frames(cubeb_stream * stm, REFERENCE_TIME hns)
+{
+  return hns_to_frames(get_rate(stm), hns);
+}
+
+REFERENCE_TIME
+frames_to_hns(uint32_t rate, uint32_t frames)
+{
+  return std::ceil(frames * 10000000.0 / rate);
+}
+
+/* This returns the size of a frame in the stream, before the eventual upmix
+   occurs. */
+static size_t
+frames_to_bytes_before_mix(cubeb_stream * stm, size_t frames)
+{
+  // This is called only when we has a output client.
+  XASSERT(has_output(stm));
+  return stm->output_stream_params.channels * stm->bytes_per_sample * frames;
+}
+
+/* This function handles the processing of the input and output audio,
+ * converting it to rate and channel layout specified at initialization.
+ * It then calls the data callback, via the resampler. */
+long
+refill(cubeb_stream * stm, void * input_buffer, long input_frames_count,
+       void * output_buffer, long output_frames_needed)
+{
+  XASSERT(!stm->draining);
+  /* If we need to upmix after resampling, resample into the mix buffer to
+     avoid a copy. Avoid exposing output if it is a dummy stream. */
+  void * dest = nullptr;
+  if (has_output(stm) && !stm->has_dummy_output) {
+    if (stm->output_mixer) {
+      dest = stm->mix_buffer.data();
+    } else {
+      dest = output_buffer;
+    }
+  }
+
+  long out_frames =
+      cubeb_resampler_fill(stm->resampler.get(), input_buffer,
+                           &input_frames_count, dest, output_frames_needed);
+  if (out_frames < 0) {
+    ALOGV("Callback refill error: %d", out_frames);
+    wasapi_state_callback(stm, stm->user_ptr, CUBEB_STATE_ERROR);
+    return out_frames;
+  }
+
+  float volume = 1.0;
+  {
+    auto_lock lock(stm->stream_reset_lock);
+    stm->frames_written += out_frames;
+    volume = stm->volume;
+  }
+
+  /* Go in draining mode if we got fewer frames than requested. If the stream
+     has no output we still expect the callback to return number of frames read
+     from input, otherwise we stop. */
+  if ((out_frames < output_frames_needed) ||
+      (!has_output(stm) && out_frames < input_frames_count)) {
+    LOG("start draining.");
+    stm->draining = true;
+  }
+
+  /* If this is not true, there will be glitches.
+     It is alright to have produced less frames if we are draining, though. */
+  XASSERT(out_frames == output_frames_needed || stm->draining ||
+          !has_output(stm) || stm->has_dummy_output);
+
+#ifndef CUBEB_WASAPI_USE_IAUDIOSTREAMVOLUME
+  if (has_output(stm) && !stm->has_dummy_output && volume != 1.0) {
+    // Adjust the output volume.
+    // Note: This could be integrated with the remixing below.
+    long out_samples = out_frames * stm->output_stream_params.channels;
+    if (volume == 0.0) {
+      memset(dest, 0, out_samples * stm->bytes_per_sample);
+    } else {
+      switch (stm->output_stream_params.format) {
+      case CUBEB_SAMPLE_FLOAT32NE: {
+        float * buf = static_cast<float *>(dest);
+        for (long i = 0; i < out_samples; ++i) {
+          buf[i] *= volume;
+        }
+        break;
+      }
+      case CUBEB_SAMPLE_S16NE: {
+        short * buf = static_cast<short *>(dest);
+        for (long i = 0; i < out_samples; ++i) {
+          buf[i] = static_cast<short>(static_cast<float>(buf[i]) * volume);
+        }
+        break;
+      }
+      default:
+        XASSERT(false);
+      }
+    }
+  }
+#endif
+
+  // We don't bother mixing dummy output as it will be silenced, otherwise mix
+  // output if needed
+  if (!stm->has_dummy_output && has_output(stm) && stm->output_mixer) {
+    XASSERT(dest == stm->mix_buffer.data());
+    size_t dest_size =
+        out_frames * stm->output_stream_params.channels * stm->bytes_per_sample;
+    XASSERT(dest_size <= stm->mix_buffer.size());
+    size_t output_buffer_size =
+        out_frames * stm->output_mix_params.channels * stm->bytes_per_sample;
+    int ret = cubeb_mixer_mix(stm->output_mixer.get(), out_frames, dest,
+                              dest_size, output_buffer, output_buffer_size);
+    if (ret < 0) {
+      LOG("Error remixing content (%d)", ret);
+    }
+  }
+
+  return out_frames;
+}
+
+bool
+trigger_async_reconfigure(cubeb_stream * stm)
+{
+  XASSERT(stm && stm->reconfigure_event);
+  LOG("Try reconfiguring the stream");
+  BOOL ok = SetEvent(stm->reconfigure_event);
+  if (!ok) {
+    LOG("SetEvent on reconfigure_event failed: %lx", GetLastError());
+  }
+  return static_cast<bool>(ok);
+}
+
+/* This helper grabs all the frames available from a capture client, put them in
+ * the linear_input_buffer.  This helper does not work with exclusive mode
+ * streams. */
+bool
+get_input_buffer(cubeb_stream * stm)
+{
+  XASSERT(has_input(stm));
+
+  HRESULT hr;
+  BYTE * input_packet = NULL;
+  DWORD flags;
+  UINT64 dev_pos;
+  UINT64 pc_position;
+  UINT32 next;
+  /* Get input packets until we have captured enough frames, and put them in a
+   * contiguous buffer. */
+  uint32_t offset = 0;
+  // If the input stream is event driven we should only ever expect to read a
+  // single packet each time. However, if we're pulling from the stream we may
+  // need to grab multiple packets worth of frames that have accumulated (so
+  // need a loop).
+  for (hr = stm->capture_client->GetNextPacketSize(&next); next > 0;
+       hr = stm->capture_client->GetNextPacketSize(&next)) {
+    if (hr == AUDCLNT_E_DEVICE_INVALIDATED) {
+      // Application can recover from this error. More info
+      // https://msdn.microsoft.com/en-us/library/windows/desktop/dd316605(v=vs.85).aspx
+      LOG("Input device invalidated error");
+      // No need to reset device if user asks to use particular device, or
+      // switching is disabled.
+      if (stm->input_device_id ||
+          (stm->input_stream_params.prefs &
+           CUBEB_STREAM_PREF_DISABLE_DEVICE_SWITCHING) ||
+          !trigger_async_reconfigure(stm)) {
+        wasapi_state_callback(stm, stm->user_ptr, CUBEB_STATE_ERROR);
+        return false;
+      }
+      return true;
+    }
+
+    if (FAILED(hr)) {
+      LOG("cannot get next packet size: %lx", hr);
+      return false;
+    }
+
+    UINT32 frames;
+    hr = stm->capture_client->GetBuffer(&input_packet, &frames, &flags,
+                                        &dev_pos, &pc_position);
+
+    if (FAILED(hr)) {
+      LOG("GetBuffer failed for capture: %lx", hr);
+      return false;
+    }
+    XASSERT(frames == next);
+
+    if (stm->context->performance_counter_frequency) {
+      LARGE_INTEGER now;
+      UINT64 now_hns;
+      // See
+      // https://docs.microsoft.com/en-us/windows/win32/api/audioclient/nf-audioclient-iaudiocaptureclient-getbuffer,
+      // section "Remarks".
+      QueryPerformanceCounter(&now);
+      now_hns =
+          10000000 * now.QuadPart / stm->context->performance_counter_frequency;
+      if (now_hns >= pc_position) {
+        stm->input_latency_hns = now_hns - pc_position;
+      }
+    }
+
+    stm->total_input_frames += frames;
+
+    UINT32 input_stream_samples = frames * stm->input_stream_params.channels;
+    // We do not explicitly handle the AUDCLNT_BUFFERFLAGS_DATA_DISCONTINUITY
+    // flag. There a two primary (non exhaustive) scenarios we anticipate this
+    // flag being set in:
+    //   - The first GetBuffer after Start has this flag undefined. In this
+    //     case the flag may be set but is meaningless and can be ignored.
+    //   - If a glitch is introduced into the input. This should not happen
+    //     for event based inputs, and should be mitigated by using a dummy
+    //     stream to drive input in the case of input only loopback. Without
+    //     a dummy output, input only loopback would glitch on silence. However,
+    //     the dummy input should push silence to the loopback and prevent
+    //     discontinuities. See
+    //     https://blogs.msdn.microsoft.com/matthew_van_eerde/2008/12/16/sample-wasapi-loopback-capture-record-what-you-hear/
+    // As the first scenario can be ignored, and we anticipate the second
+    // scenario is mitigated, we ignore the flag.
+    // For more info:
+    // https://msdn.microsoft.com/en-us/library/windows/desktop/dd370859(v=vs.85).aspx,
+    // https://msdn.microsoft.com/en-us/library/windows/desktop/dd371458(v=vs.85).aspx
+    if (flags & AUDCLNT_BUFFERFLAGS_SILENT) {
+      LOG("insert silence: ps=%u", frames);
+      stm->linear_input_buffer->push_silence(input_stream_samples);
+    } else {
+      if (stm->input_mixer) {
+        bool ok = stm->linear_input_buffer->reserve(
+            stm->linear_input_buffer->length() + input_stream_samples);
+        XASSERT(ok);
+        size_t input_packet_size =
+            frames * stm->input_mix_params.channels *
+            cubeb_sample_size(stm->input_mix_params.format);
+        size_t linear_input_buffer_size =
+            input_stream_samples *
+            cubeb_sample_size(stm->input_stream_params.format);
+        cubeb_mixer_mix(stm->input_mixer.get(), frames, input_packet,
+                        input_packet_size, stm->linear_input_buffer->end(),
+                        linear_input_buffer_size);
+        stm->linear_input_buffer->set_length(
+            stm->linear_input_buffer->length() + input_stream_samples);
+      } else {
+        stm->linear_input_buffer->push(input_packet, input_stream_samples);
+      }
+    }
+    hr = stm->capture_client->ReleaseBuffer(frames);
+    if (FAILED(hr)) {
+      LOG("FAILED to release intput buffer");
+      return false;
+    }
+    offset += input_stream_samples;
+  }
+
+  ALOGV("get_input_buffer: got %d frames", offset);
+
+  XASSERT(stm->linear_input_buffer->length() >= offset);
+
+  return true;
+}
+
+/* Get an output buffer from the render_client. It has to be released before
+ * exiting the callback. */
+bool
+get_output_buffer(cubeb_stream * stm, void *& buffer, size_t & frame_count)
+{
+  UINT32 padding_out;
+  HRESULT hr;
+
+  XASSERT(has_output(stm));
+
+  hr = stm->output_client->GetCurrentPadding(&padding_out);
+  if (hr == AUDCLNT_E_DEVICE_INVALIDATED) {
+    // Application can recover from this error. More info
+    // https://msdn.microsoft.com/en-us/library/windows/desktop/dd316605(v=vs.85).aspx
+    LOG("Output device invalidated error");
+    // No need to reset device if user asks to use particular device, or
+    // switching is disabled.
+    if (stm->output_device_id ||
+        (stm->output_stream_params.prefs &
+         CUBEB_STREAM_PREF_DISABLE_DEVICE_SWITCHING) ||
+        !trigger_async_reconfigure(stm)) {
+      wasapi_state_callback(stm, stm->user_ptr, CUBEB_STATE_ERROR);
+      return false;
+    }
+    return true;
+  }
+
+  if (FAILED(hr)) {
+    LOG("Failed to get padding: %lx", hr);
+    return false;
+  }
+
+  XASSERT(padding_out <= stm->output_buffer_frame_count);
+
+  if (stm->draining) {
+    if (padding_out == 0) {
+      LOG("Draining finished.");
+      wasapi_state_callback(stm, stm->user_ptr, CUBEB_STATE_DRAINED);
+      return false;
+    }
+    LOG("Draining.");
+    return true;
+  }
+
+  frame_count = stm->output_buffer_frame_count - padding_out;
+  BYTE * output_buffer;
+
+  hr = stm->render_client->GetBuffer(frame_count, &output_buffer);
+  if (FAILED(hr)) {
+    LOG("cannot get render buffer");
+    return false;
+  }
+
+  buffer = output_buffer;
+
+  return true;
+}
+
+/**
+ * This function gets input data from a input device, and pass it along with an
+ * output buffer to the resamplers.  */
+bool
+refill_callback_duplex(cubeb_stream * stm)
+{
+  HRESULT hr;
+  void * output_buffer = nullptr;
+  size_t output_frames = 0;
+  size_t input_frames;
+  bool rv;
+
+  XASSERT(has_input(stm) && has_output(stm));
+
+  if (stm->input_stream_params.prefs & CUBEB_STREAM_PREF_LOOPBACK) {
+    HRESULT rv = get_input_buffer(stm);
+    if (FAILED(rv)) {
+      return rv;
+    }
+  }
+
+  input_frames =
+      stm->linear_input_buffer->length() / stm->input_stream_params.channels;
+
+  rv = get_output_buffer(stm, output_buffer, output_frames);
+  if (!rv) {
+    hr = stm->render_client->ReleaseBuffer(output_frames, 0);
+    return rv;
+  }
+
+  /* This can only happen when debugging, and having breakpoints set in the
+   * callback in a way that it makes the stream underrun. */
+  if (output_frames == 0) {
+    return true;
+  }
+
+  /* Wait for draining is not important on duplex. */
+  if (stm->draining) {
+    return false;
+  }
+
+  stm->total_output_frames += output_frames;
+
+  ALOGV("in: %zu, out: %zu, missing: %ld, ratio: %f", stm->total_input_frames,
+        stm->total_output_frames,
+        static_cast<long>(stm->total_output_frames) - stm->total_input_frames,
+        static_cast<float>(stm->total_output_frames) / stm->total_input_frames);
+
+  long got;
+  if (stm->has_dummy_output) {
+    ALOGV(
+        "Duplex callback (dummy output): input frames: %Iu, output frames: %Iu",
+        input_frames, output_frames);
+
+    // We don't want to expose the dummy output to the callback so don't pass
+    // the output buffer (it will be released later with silence in it)
+    got =
+        refill(stm, stm->linear_input_buffer->data(), input_frames, nullptr, 0);
+
+  } else {
+    ALOGV("Duplex callback: input frames: %Iu, output frames: %Iu",
+          input_frames, output_frames);
+
+    got = refill(stm, stm->linear_input_buffer->data(), input_frames,
+                 output_buffer, output_frames);
+  }
+
+  stm->linear_input_buffer->clear();
+
+  if (stm->has_dummy_output) {
+    // If output is a dummy output, make sure it's silent
+    hr = stm->render_client->ReleaseBuffer(output_frames,
+                                           AUDCLNT_BUFFERFLAGS_SILENT);
+  } else {
+    hr = stm->render_client->ReleaseBuffer(output_frames, 0);
+  }
+  if (FAILED(hr)) {
+    LOG("failed to release buffer: %lx", hr);
+    return false;
+  }
+  if (got < 0) {
+    return false;
+  }
+  return true;
+}
+
+bool
+refill_callback_input(cubeb_stream * stm)
+{
+  bool rv;
+  size_t input_frames;
+
+  XASSERT(has_input(stm) && !has_output(stm));
+
+  rv = get_input_buffer(stm);
+  if (!rv) {
+    return rv;
+  }
+
+  input_frames =
+      stm->linear_input_buffer->length() / stm->input_stream_params.channels;
+  if (!input_frames) {
+    return true;
+  }
+
+  ALOGV("Input callback: input frames: %Iu", input_frames);
+
+  long read =
+      refill(stm, stm->linear_input_buffer->data(), input_frames, nullptr, 0);
+  if (read < 0) {
+    return false;
+  }
+
+  stm->linear_input_buffer->clear();
+
+  return !stm->draining;
+}
+
+bool
+refill_callback_output(cubeb_stream * stm)
+{
+  bool rv;
+  HRESULT hr;
+  void * output_buffer = nullptr;
+  size_t output_frames = 0;
+
+  XASSERT(!has_input(stm) && has_output(stm));
+
+  rv = get_output_buffer(stm, output_buffer, output_frames);
+  if (!rv) {
+    return rv;
+  }
+
+  if (stm->draining || output_frames == 0) {
+    return true;
+  }
+
+  long got = refill(stm, nullptr, 0, output_buffer, output_frames);
+
+  ALOGV("Output callback: output frames requested: %Iu, got %ld", output_frames,
+        got);
+  if (got < 0) {
+    return false;
+  }
+  XASSERT(size_t(got) == output_frames || stm->draining);
+
+  hr = stm->render_client->ReleaseBuffer(got, 0);
+  if (FAILED(hr)) {
+    LOG("failed to release buffer: %lx", hr);
+    return false;
+  }
+
+  return size_t(got) == output_frames || stm->draining;
+}
+
+void
+wasapi_stream_destroy(cubeb_stream * stm);
+
+static unsigned int __stdcall wasapi_stream_render_loop(LPVOID stream)
+{
+  AutoRegisterThread raii("cubeb rendering thread");
+  cubeb_stream * stm = static_cast<cubeb_stream *>(stream);
+
+  auto_stream_ref stream_ref(stm);
+  struct auto_com {
+    auto_com()
+    {
+      HRESULT hr = CoInitializeEx(nullptr, COINIT_MULTITHREADED);
+      XASSERT(SUCCEEDED(hr));
+    }
+    ~auto_com() { CoUninitialize(); }
+  } com;
+
+  bool is_playing = true;
+  HANDLE wait_array[4] = {stm->shutdown_event, stm->reconfigure_event,
+                          stm->refill_event, stm->input_available_event};
+  HANDLE mmcss_handle = NULL;
+  HRESULT hr = 0;
+  DWORD mmcss_task_index = 0;
+
+  // Signal wasapi_stream_start that we've initialized COM and incremented
+  // the stream's ref_count.
+  BOOL ok = SetEvent(stm->thread_ready_event);
+  if (!ok) {
+    LOG("thread_ready SetEvent failed: %lx", GetLastError());
+    return 0;
+  }
+
+  /* We could consider using "Pro Audio" here for WebAudio and
+     maybe WebRTC. */
+  mmcss_handle = AvSetMmThreadCharacteristicsA("Audio", &mmcss_task_index);
+  if (!mmcss_handle) {
+    /* This is not fatal, but we might glitch under heavy load. */
+    LOG("Unable to use mmcss to bump the render thread priority: %lx",
+        GetLastError());
+  }
+
+  while (is_playing) {
+    DWORD waitResult = WaitForMultipleObjects(ARRAY_LENGTH(wait_array),
+                                              wait_array, FALSE, INFINITE);
+    switch (waitResult) {
+    case WAIT_OBJECT_0: { /* shutdown */
+      is_playing = false;
+      /* We don't check if the drain is actually finished here, we just want to
+         shutdown. */
+      if (stm->draining) {
+        wasapi_state_callback(stm, stm->user_ptr, CUBEB_STATE_DRAINED);
+      }
+      continue;
+    }
+    case WAIT_OBJECT_0 + 1: { /* reconfigure */
+      auto_lock lock(stm->stream_reset_lock);
+      if (!stm->active) {
+        /* Avoid reconfiguring, stream start will handle it. */
+        LOG("Stream is not active, ignoring reconfigure.");
+        continue;
+      }
+      XASSERT(stm->output_client || stm->input_client);
+      LOG("Reconfiguring the stream");
+      /* Close the stream */
+      bool was_running = false;
+      if (stm->output_client) {
+        was_running = stm->output_client->Stop() == S_OK;
+        LOG("Output stopped.");
+      }
+      if (stm->input_client) {
+        was_running = stm->input_client->Stop() == S_OK;
+        LOG("Input stopped.");
+      }
+      close_wasapi_stream(stm);
+      LOG("Stream closed.");
+      /* Reopen a stream and start it immediately. This will automatically
+          pick the new default device for this role. */
+      int r = setup_wasapi_stream(stm);
+      if (r != CUBEB_OK) {
+        LOG("Error setting up the stream during reconfigure.");
+        /* Don't destroy the stream here, since we expect the caller to do
+            so after the error has propagated via the state callback. */
+        is_playing = false;
+        hr = E_FAIL;
+        continue;
+      }
+      LOG("Stream setup successfuly.");
+      XASSERT(stm->output_client || stm->input_client);
+      if (was_running && stm->output_client) {
+        hr = stm->output_client->Start();
+        if (FAILED(hr)) {
+          LOG("Error starting output after reconfigure, error: %lx", hr);
+          is_playing = false;
+          continue;
+        }
+        LOG("Output started after reconfigure.");
+      }
+      if (was_running && stm->input_client) {
+        hr = stm->input_client->Start();
+        if (FAILED(hr)) {
+          LOG("Error starting input after reconfiguring, error: %lx", hr);
+          is_playing = false;
+          continue;
+        }
+        LOG("Input started after reconfigure.");
+      }
+      break;
+    }
+    case WAIT_OBJECT_0 + 2: /* refill */
+      XASSERT((has_input(stm) && has_output(stm)) ||
+              (!has_input(stm) && has_output(stm)));
+      is_playing = stm->refill_callback(stm);
+      break;
+    case WAIT_OBJECT_0 + 3: { /* input available */
+      HRESULT rv = get_input_buffer(stm);
+      if (FAILED(rv)) {
+        is_playing = false;
+        continue;
+      }
+
+      if (!has_output(stm)) {
+        is_playing = stm->refill_callback(stm);
+      }
+
+      break;
+    }
+    default:
+      LOG("case %lu not handled in render loop.", waitResult);
+      XASSERT(false);
+    }
+  }
+
+  // Stop audio clients since this thread will no longer service
+  // the events.
+  if (stm->output_client) {
+    stm->output_client->Stop();
+  }
+  if (stm->input_client) {
+    stm->input_client->Stop();
+  }
+
+  if (mmcss_handle) {
+    AvRevertMmThreadCharacteristics(mmcss_handle);
+  }
+
+  if (FAILED(hr)) {
+    wasapi_state_callback(stm, stm->user_ptr, CUBEB_STATE_ERROR);
+  }
+
+  return 0;
+}
+
+void
+wasapi_destroy(cubeb * context);
+
+HRESULT
+register_notification_client(cubeb_stream * stm)
+{
+  XASSERT(stm->device_enumerator && !stm->notification_client);
+
+  stm->notification_client.reset(new wasapi_endpoint_notification_client(
+      stm->reconfigure_event, stm->role));
+
+  HRESULT hr = stm->device_enumerator->RegisterEndpointNotificationCallback(
+      stm->notification_client.get());
+  if (FAILED(hr)) {
+    LOG("Could not register endpoint notification callback: %lx", hr);
+    stm->notification_client = nullptr;
+  }
+
+  return hr;
+}
+
+HRESULT
+unregister_notification_client(cubeb_stream * stm)
+{
+  XASSERT(stm->device_enumerator && stm->notification_client);
+
+  HRESULT hr = stm->device_enumerator->UnregisterEndpointNotificationCallback(
+      stm->notification_client.get());
+  if (FAILED(hr)) {
+    // We can't really do anything here, we'll probably leak the
+    // notification client.
+    return S_OK;
+  }
+
+  stm->notification_client = nullptr;
+
+  return S_OK;
+}
+
+HRESULT
+get_endpoint(com_ptr<IMMDevice> & device, LPCWSTR devid)
+{
+  com_ptr<IMMDeviceEnumerator> enumerator;
+  HRESULT hr =
+      CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL, CLSCTX_INPROC_SERVER,
+                       IID_PPV_ARGS(enumerator.receive()));
+  if (FAILED(hr)) {
+    LOG("Could not get device enumerator: %lx", hr);
+    return hr;
+  }
+
+  hr = enumerator->GetDevice(devid, device.receive());
+  if (FAILED(hr)) {
+    LOG("Could not get device: %lx", hr);
+    return hr;
+  }
+
+  return S_OK;
+}
+
+HRESULT
+register_collection_notification_client(cubeb * context)
+{
+  context->lock.assert_current_thread_owns();
+  XASSERT(!context->device_collection_enumerator &&
+          !context->collection_notification_client);
+  HRESULT hr = CoCreateInstance(
+      __uuidof(MMDeviceEnumerator), NULL, CLSCTX_INPROC_SERVER,
+      IID_PPV_ARGS(context->device_collection_enumerator.receive()));
+  if (FAILED(hr)) {
+    LOG("Could not get device enumerator: %lx", hr);
+    return hr;
+  }
+
+  context->collection_notification_client.reset(
+      new wasapi_collection_notification_client(context));
+
+  hr = context->device_collection_enumerator
+           ->RegisterEndpointNotificationCallback(
+               context->collection_notification_client.get());
+  if (FAILED(hr)) {
+    LOG("Could not register endpoint notification callback: %lx", hr);
+    context->collection_notification_client.reset();
+    context->device_collection_enumerator.reset();
+  }
+
+  return hr;
+}
+
+HRESULT
+unregister_collection_notification_client(cubeb * context)
+{
+  context->lock.assert_current_thread_owns();
+  XASSERT(context->device_collection_enumerator &&
+          context->collection_notification_client);
+  HRESULT hr = context->device_collection_enumerator
+                   ->UnregisterEndpointNotificationCallback(
+                       context->collection_notification_client.get());
+  if (FAILED(hr)) {
+    return hr;
+  }
+
+  context->collection_notification_client = nullptr;
+  context->device_collection_enumerator = nullptr;
+
+  return hr;
+}
+
+HRESULT
+get_default_endpoint(com_ptr<IMMDevice> & device, EDataFlow direction,
+                     ERole role)
+{
+  com_ptr<IMMDeviceEnumerator> enumerator;
+  HRESULT hr =
+      CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL, CLSCTX_INPROC_SERVER,
+                       IID_PPV_ARGS(enumerator.receive()));
+  if (FAILED(hr)) {
+    LOG("Could not get device enumerator: %lx", hr);
+    return hr;
+  }
+  hr = enumerator->GetDefaultAudioEndpoint(direction, role, device.receive());
+  if (FAILED(hr)) {
+    LOG("Could not get default audio endpoint: %lx", hr);
+    return hr;
+  }
+
+  return ERROR_SUCCESS;
+}
+
+double
+current_stream_delay(cubeb_stream * stm)
+{
+  stm->stream_reset_lock.assert_current_thread_owns();
+
+  /* If the default audio endpoint went away during playback and we weren't
+     able to configure a new one, it's possible the caller may call this
+     before the error callback has propogated back. */
+  if (!stm->audio_clock) {
+    return 0;
+  }
+
+  UINT64 freq;
+  HRESULT hr = stm->audio_clock->GetFrequency(&freq);
+  if (FAILED(hr)) {
+    LOG("GetFrequency failed: %lx", hr);
+    return 0;
+  }
+
+  UINT64 pos;
+  hr = stm->audio_clock->GetPosition(&pos, NULL);
+  if (FAILED(hr)) {
+    LOG("GetPosition failed: %lx", hr);
+    return 0;
+  }
+
+  double cur_pos = static_cast<double>(pos) / freq;
+  double max_pos =
+      static_cast<double>(stm->frames_written) / stm->output_mix_params.rate;
+  double delay = std::max(max_pos - cur_pos, 0.0);
+
+  return delay;
+}
+
+#ifdef CUBEB_WASAPI_USE_IAUDIOSTREAMVOLUME
+int
+stream_set_volume(cubeb_stream * stm, float volume)
+{
+  stm->stream_reset_lock.assert_current_thread_owns();
+
+  if (!stm->audio_stream_volume) {
+    return CUBEB_ERROR;
+  }
+
+  uint32_t channels;
+  HRESULT hr = stm->audio_stream_volume->GetChannelCount(&channels);
+  if (FAILED(hr)) {
+    LOG("could not get the channel count: %lx", hr);
+    return CUBEB_ERROR;
+  }
+
+  /* up to 9.1 for now */
+  if (channels > 10) {
+    return CUBEB_ERROR_NOT_SUPPORTED;
+  }
+
+  float volumes[10];
+  for (uint32_t i = 0; i < channels; i++) {
+    volumes[i] = volume;
+  }
+
+  hr = stm->audio_stream_volume->SetAllVolumes(channels, volumes);
+  if (FAILED(hr)) {
+    LOG("could not set the channels volume: %lx", hr);
+    return CUBEB_ERROR;
+  }
+
+  return CUBEB_OK;
+}
+#endif
+} // namespace
+
+extern "C" {
+int
+wasapi_init(cubeb ** context, char const * context_name)
+{
+  /* We don't use the device yet, but need to make sure we can initialize one
+     so that this backend is not incorrectly enabled on platforms that don't
+     support WASAPI. */
+  com_ptr<IMMDevice> device;
+  HRESULT hr = get_default_endpoint(device, eRender, eConsole);
+  if (FAILED(hr)) {
+    XASSERT(hr != CO_E_NOTINITIALIZED);
+    LOG("It wasn't able to find a default rendering device: %lx", hr);
+    hr = get_default_endpoint(device, eCapture, eConsole);
+    if (FAILED(hr)) {
+      LOG("It wasn't able to find a default capture device: %lx", hr);
+      return CUBEB_ERROR;
+    }
+  }
+
+  cubeb * ctx = new cubeb();
+
+  ctx->ops = &wasapi_ops;
+  auto_lock lock(ctx->lock);
+  if (cubeb_strings_init(&ctx->device_ids) != CUBEB_OK) {
+    delete ctx;
+    return CUBEB_ERROR;
+  }
+
+  LARGE_INTEGER frequency;
+  if (QueryPerformanceFrequency(&frequency)) {
+    ctx->performance_counter_frequency = frequency.QuadPart;
+  } else {
+    LOG("Failed getting performance counter frequency, latency reporting will "
+        "be inacurate");
+    ctx->performance_counter_frequency = 0;
+  }
+
+  *context = ctx;
+
+  return CUBEB_OK;
+}
+}
+
+namespace {
+enum ShutdownPhase { OnStop, OnDestroy };
+
+bool
+stop_and_join_render_thread(cubeb_stream * stm)
+{
+  LOG("%p: Stop and join render thread: %p", stm, stm->thread);
+  if (!stm->thread) {
+    return true;
+  }
+
+  BOOL ok = SetEvent(stm->shutdown_event);
+  if (!ok) {
+    LOG("stop_and_join_render_thread: SetEvent failed: %lx", GetLastError());
+    return false;
+  }
+
+  /* Wait five seconds for the rendering thread to return. It's supposed to
+   * check its event loop very often, five seconds is rather conservative.
+   * Note: 5*1s loop to work around timer sleep issues on pre-Windows 8. */
+  DWORD r;
+  for (int i = 0; i < 5; ++i) {
+    r = WaitForSingleObject(stm->thread, 1000);
+    if (r == WAIT_OBJECT_0) {
+      break;
+    }
+  }
+  if (r != WAIT_OBJECT_0) {
+    LOG("stop_and_join_render_thread: WaitForSingleObject on thread failed: "
+        "%lx, %lx",
+        r, GetLastError());
+    return false;
+  }
+
+  return true;
+}
+
+void
+wasapi_destroy(cubeb * context)
+{
+  {
+    auto_lock lock(context->lock);
+    XASSERT(!context->device_collection_enumerator &&
+            !context->collection_notification_client);
+
+    if (context->device_ids) {
+      cubeb_strings_destroy(context->device_ids);
+    }
+  }
+
+  delete context;
+}
+
+char const *
+wasapi_get_backend_id(cubeb * context)
+{
+  return "wasapi";
+}
+
+int
+wasapi_get_max_channel_count(cubeb * ctx, uint32_t * max_channels)
+{
+  XASSERT(ctx && max_channels);
+
+  com_ptr<IMMDevice> device;
+  HRESULT hr = get_default_endpoint(device, eRender, eConsole);
+  if (FAILED(hr)) {
+    return CUBEB_ERROR;
+  }
+
+  com_ptr<IAudioClient> client;
+  hr = device->Activate(__uuidof(IAudioClient), CLSCTX_INPROC_SERVER, NULL,
+                        client.receive_vpp());
+  if (FAILED(hr)) {
+    return CUBEB_ERROR;
+  }
+
+  WAVEFORMATEX * tmp = nullptr;
+  hr = client->GetMixFormat(&tmp);
+  if (FAILED(hr)) {
+    return CUBEB_ERROR;
+  }
+  com_heap_ptr<WAVEFORMATEX> mix_format(tmp);
+
+  *max_channels = mix_format->nChannels;
+
+  return CUBEB_OK;
+}
+
+int
+wasapi_get_min_latency(cubeb * ctx, cubeb_stream_params params,
+                       uint32_t * latency_frames)
+{
+  if (params.format != CUBEB_SAMPLE_FLOAT32NE &&
+      params.format != CUBEB_SAMPLE_S16NE) {
+    return CUBEB_ERROR_INVALID_FORMAT;
+  }
+
+  ERole role = pref_to_role(params.prefs);
+
+  com_ptr<IMMDevice> device;
+  HRESULT hr = get_default_endpoint(device, eRender, role);
+  if (FAILED(hr)) {
+    LOG("Could not get default endpoint: %lx", hr);
+    return CUBEB_ERROR;
+  }
+
+  com_ptr<IAudioClient> client;
+  hr = device->Activate(__uuidof(IAudioClient), CLSCTX_INPROC_SERVER, NULL,
+                        client.receive_vpp());
+  if (FAILED(hr)) {
+    LOG("Could not activate device for latency: %lx", hr);
+    return CUBEB_ERROR;
+  }
+
+  REFERENCE_TIME minimum_period;
+  REFERENCE_TIME default_period;
+  hr = client->GetDevicePeriod(&default_period, &minimum_period);
+  if (FAILED(hr)) {
+    LOG("Could not get device period: %lx", hr);
+    return CUBEB_ERROR;
+  }
+
+  LOG("default device period: %I64d, minimum device period: %I64d",
+      default_period, minimum_period);
+
+  /* If we're on Windows 10, we can use IAudioClient3 to get minimal latency.
+     Otherwise, according to the docs, the best latency we can achieve is by
+     synchronizing the stream and the engine.
+     http://msdn.microsoft.com/en-us/library/windows/desktop/dd370871%28v=vs.85%29.aspx
+   */
+
+  // #ifdef _WIN32_WINNT_WIN10
+#if 0
+     *latency_frames = hns_to_frames(params.rate, minimum_period);
+#else
+  *latency_frames = hns_to_frames(params.rate, default_period);
+#endif
+
+  LOG("Minimum latency in frames: %u", *latency_frames);
+
+  return CUBEB_OK;
+}
+
+int
+wasapi_get_preferred_sample_rate(cubeb * ctx, uint32_t * rate)
+{
+  com_ptr<IMMDevice> device;
+  HRESULT hr = get_default_endpoint(device, eRender, eConsole);
+  if (FAILED(hr)) {
+    return CUBEB_ERROR;
+  }
+
+  com_ptr<IAudioClient> client;
+  hr = device->Activate(__uuidof(IAudioClient), CLSCTX_INPROC_SERVER, NULL,
+                        client.receive_vpp());
+  if (FAILED(hr)) {
+    return CUBEB_ERROR;
+  }
+
+  WAVEFORMATEX * tmp = nullptr;
+  hr = client->GetMixFormat(&tmp);
+  if (FAILED(hr)) {
+    return CUBEB_ERROR;
+  }
+  com_heap_ptr<WAVEFORMATEX> mix_format(tmp);
+
+  *rate = mix_format->nSamplesPerSec;
+
+  LOG("Preferred sample rate for output: %u", *rate);
+
+  return CUBEB_OK;
+}
+
+static void
+waveformatex_update_derived_properties(WAVEFORMATEX * format)
+{
+  format->nBlockAlign = format->wBitsPerSample * format->nChannels / 8;
+  format->nAvgBytesPerSec = format->nSamplesPerSec * format->nBlockAlign;
+  if (format->wFormatTag == WAVE_FORMAT_EXTENSIBLE) {
+    WAVEFORMATEXTENSIBLE * format_pcm =
+        reinterpret_cast<WAVEFORMATEXTENSIBLE *>(format);
+    format_pcm->Samples.wValidBitsPerSample = format->wBitsPerSample;
+  }
+}
+
+/* Based on the mix format and the stream format, try to find a way to play
+   what the user requested. */
+static void
+handle_channel_layout(cubeb_stream * stm, EDataFlow direction,
+                      com_heap_ptr<WAVEFORMATEX> & mix_format,
+                      const cubeb_stream_params * stream_params)
+{
+  com_ptr<IAudioClient> & audio_client =
+      (direction == eRender) ? stm->output_client : stm->input_client;
+  XASSERT(audio_client);
+  /* The docs say that GetMixFormat is always of type WAVEFORMATEXTENSIBLE [1],
+     so the reinterpret_cast below should be safe. In practice, this is not
+     true, and we just want to bail out and let the rest of the code find a good
+     conversion path instead of trying to make WASAPI do it by itself.
+     [1]:
+     http://msdn.microsoft.com/en-us/library/windows/desktop/dd370811%28v=vs.85%29.aspx*/
+  if (mix_format->wFormatTag != WAVE_FORMAT_EXTENSIBLE) {
+    return;
+  }
+
+  WAVEFORMATEXTENSIBLE * format_pcm =
+      reinterpret_cast<WAVEFORMATEXTENSIBLE *>(mix_format.get());
+
+  /* Stash a copy of the original mix format in case we need to restore it
+   * later. */
+  WAVEFORMATEXTENSIBLE hw_mix_format = *format_pcm;
+
+  /* Get the channel mask by the channel layout.
+     If the layout is not supported, we will get a closest settings below. */
+  format_pcm->dwChannelMask = stream_params->layout;
+  mix_format->nChannels = stream_params->channels;
+  waveformatex_update_derived_properties(mix_format.get());
+
+  /* Check if wasapi will accept our channel layout request. */
+  WAVEFORMATEX * tmp = nullptr;
+  HRESULT hr = audio_client->IsFormatSupported(AUDCLNT_SHAREMODE_SHARED,
+                                               mix_format.get(), &tmp);
+  com_heap_ptr<WAVEFORMATEX> closest(tmp);
+  if (hr == S_FALSE) {
+    /* Channel layout not supported, but WASAPI gives us a suggestion. Use it,
+       and handle the eventual upmix/downmix ourselves. Ignore the subformat of
+       the suggestion, since it seems to always be IEEE_FLOAT. */
+    LOG("Using WASAPI suggested format: channels: %d", closest->nChannels);
+    XASSERT(closest->wFormatTag == WAVE_FORMAT_EXTENSIBLE);
+    WAVEFORMATEXTENSIBLE * closest_pcm =
+        reinterpret_cast<WAVEFORMATEXTENSIBLE *>(closest.get());
+    format_pcm->dwChannelMask = closest_pcm->dwChannelMask;
+    mix_format->nChannels = closest->nChannels;
+    waveformatex_update_derived_properties(mix_format.get());
+  } else if (hr == AUDCLNT_E_UNSUPPORTED_FORMAT) {
+    /* Not supported, no suggestion. This should not happen, but it does in the
+       field with some sound cards. We restore the mix format, and let the rest
+       of the code figure out the right conversion path. */
+    XASSERT(mix_format->wFormatTag == WAVE_FORMAT_EXTENSIBLE);
+    *reinterpret_cast<WAVEFORMATEXTENSIBLE *>(mix_format.get()) = hw_mix_format;
+  } else if (hr == S_OK) {
+    LOG("Requested format accepted by WASAPI.");
+  } else {
+    LOG("IsFormatSupported unhandled error: %lx", hr);
+  }
+}
+
+static int
+initialize_iaudioclient2(com_ptr<IAudioClient> & audio_client)
+{
+  com_ptr<IAudioClient2> audio_client2;
+  audio_client->QueryInterface<IAudioClient2>(audio_client2.receive());
+  if (!audio_client2) {
+    LOG("Could not get IAudioClient2 interface, not setting "
+        "AUDCLNT_STREAMOPTIONS_RAW.");
+    return CUBEB_OK;
+  }
+  AudioClientProperties properties = {0};
+  properties.cbSize = sizeof(AudioClientProperties);
+#ifndef __MINGW32__
+  properties.Options |= AUDCLNT_STREAMOPTIONS_RAW;
+#endif
+  HRESULT hr = audio_client2->SetClientProperties(&properties);
+  if (FAILED(hr)) {
+    LOG("IAudioClient2::SetClientProperties error: %lx", GetLastError());
+    return CUBEB_ERROR;
+  }
+  return CUBEB_OK;
+}
+
+#if 0
+bool
+initialize_iaudioclient3(com_ptr<IAudioClient> & audio_client,
+                         cubeb_stream * stm,
+                         const com_heap_ptr<WAVEFORMATEX> & mix_format,
+                         DWORD flags, EDataFlow direction)
+{
+  com_ptr<IAudioClient3> audio_client3;
+  audio_client->QueryInterface<IAudioClient3>(audio_client3.receive());
+  if (!audio_client3) {
+    LOG("Could not get IAudioClient3 interface");
+    return false;
+  }
+
+  if (flags & AUDCLNT_STREAMFLAGS_LOOPBACK) {
+    // IAudioClient3 doesn't work with loopback streams, and will return error
+    // 88890021: AUDCLNT_E_INVALID_STREAM_FLAG
+    LOG("Audio stream is loopback, not using IAudioClient3");
+    return false;
+  }
+
+  // Some people have reported glitches with capture streams:
+  // http://blog.nirbheek.in/2018/03/low-latency-audio-on-windows-with.html
+  if (direction == eCapture) {
+    LOG("Audio stream is capture, not using IAudioClient3");
+    return false;
+  }
+
+  // Possibly initialize a shared-mode stream using IAudioClient3. Initializing
+  // a stream this way lets you request lower latencies, but also locks the
+  // global WASAPI engine at that latency.
+  // - If we request a shared-mode stream, streams created with IAudioClient
+  // will
+  //   have their latency adjusted to match. When  the shared-mode stream is
+  //   closed, they'll go back to normal.
+  // - If there's already a shared-mode stream running, then we cannot request
+  //   the engine change to a different latency - we have to match it.
+  // - It's antisocial to lock the WASAPI engine at its default latency. If we
+  //   would do this, then stop and use IAudioClient instead.
+
+  HRESULT hr;
+  uint32_t default_period = 0, fundamental_period = 0, min_period = 0,
+           max_period = 0;
+  hr = audio_client3->GetSharedModeEnginePeriod(
+      mix_format.get(), &default_period, &fundamental_period, &min_period,
+      &max_period);
+  if (FAILED(hr)) {
+    LOG("Could not get shared mode engine period: error: %lx", hr);
+    return false;
+  }
+  uint32_t requested_latency = stm->latency;
+  if (requested_latency >= default_period) {
+    LOG("Requested latency %i greater than default latency %i, not using "
+        "IAudioClient3",
+        requested_latency, default_period);
+    return false;
+  }
+  LOG("Got shared mode engine period: default=%i fundamental=%i min=%i max=%i",
+      default_period, fundamental_period, min_period, max_period);
+  // Snap requested latency to a valid value
+  uint32_t old_requested_latency = requested_latency;
+  if (requested_latency < min_period) {
+    requested_latency = min_period;
+  }
+  requested_latency -= (requested_latency - min_period) % fundamental_period;
+  if (requested_latency != old_requested_latency) {
+    LOG("Requested latency %i was adjusted to %i", old_requested_latency,
+        requested_latency);
+  }
+
+  hr = audio_client3->InitializeSharedAudioStream(flags, requested_latency,
+                                                  mix_format.get(), NULL);
+  if (SUCCEEDED(hr)) {
+    return true;
+  } else if (hr == AUDCLNT_E_ENGINE_PERIODICITY_LOCKED) {
+    LOG("Got AUDCLNT_E_ENGINE_PERIODICITY_LOCKED, adjusting latency request");
+  } else {
+    LOG("Could not initialize shared stream with IAudioClient3: error: %lx",
+        hr);
+    return false;
+  }
+
+  uint32_t current_period = 0;
+  WAVEFORMATEX * current_format = nullptr;
+  // We have to pass a valid WAVEFORMATEX** and not nullptr, otherwise
+  // GetCurrentSharedModeEnginePeriod will return E_POINTER
+  hr = audio_client3->GetCurrentSharedModeEnginePeriod(&current_format,
+                                                       &current_period);
+  CoTaskMemFree(current_format);
+  if (FAILED(hr)) {
+    LOG("Could not get current shared mode engine period: error: %lx", hr);
+    return false;
+  }
+
+  if (current_period >= default_period) {
+    LOG("Current shared mode engine period %i too high, not using IAudioClient",
+        current_period);
+    return false;
+  }
+
+  hr = audio_client3->InitializeSharedAudioStream(flags, current_period,
+                                                  mix_format.get(), NULL);
+  if (SUCCEEDED(hr)) {
+    LOG("Current shared mode engine period is %i instead of requested %i",
+        current_period, requested_latency);
+    return true;
+  }
+
+  LOG("Could not initialize shared stream with IAudioClient3: error: %lx", hr);
+  return false;
+}
+#endif
+
+#define DIRECTION_NAME (direction == eCapture ? "capture" : "render")
+
+template <typename T>
+int
+setup_wasapi_stream_one_side(cubeb_stream * stm,
+                             cubeb_stream_params * stream_params,
+                             wchar_t const * devid, EDataFlow direction,
+                             REFIID riid, com_ptr<IAudioClient> & audio_client,
+                             uint32_t * buffer_frame_count, HANDLE & event,
+                             T & render_or_capture_client,
+                             cubeb_stream_params * mix_params,
+                             com_ptr<IMMDevice> & device)
+{
+  XASSERT(direction == eCapture || direction == eRender);
+
+  HRESULT hr;
+  bool is_loopback = stream_params->prefs & CUBEB_STREAM_PREF_LOOPBACK;
+  if (is_loopback && direction != eCapture) {
+    LOG("Loopback pref can only be used with capture streams!\n");
+    return CUBEB_ERROR;
+  }
+
+  stm->stream_reset_lock.assert_current_thread_owns();
+  // If user doesn't specify a particular device, we can choose another one when
+  // the given devid is unavailable.
+  bool allow_fallback =
+      direction == eCapture ? !stm->input_device_id : !stm->output_device_id;
+  bool try_again = false;
+  // This loops until we find a device that works, or we've exhausted all
+  // possibilities.
+  do {
+    if (devid) {
+      hr = get_endpoint(device, devid);
+      if (FAILED(hr)) {
+        LOG("Could not get %s endpoint, error: %lx\n", DIRECTION_NAME, hr);
+        return CUBEB_ERROR;
+      }
+    } else {
+      // If caller has requested loopback but not specified a device, look for
+      // the default render device. Otherwise look for the default device
+      // appropriate to the direction.
+      hr = get_default_endpoint(device, is_loopback ? eRender : direction,
+                                pref_to_role(stream_params->prefs));
+      if (FAILED(hr)) {
+        if (is_loopback) {
+          LOG("Could not get default render endpoint for loopback, error: "
+              "%lx\n",
+              hr);
+        } else {
+          LOG("Could not get default %s endpoint, error: %lx\n", DIRECTION_NAME,
+              hr);
+        }
+        return CUBEB_ERROR;
+      }
+    }
+
+    /* Get a client. We will get all other interfaces we need from
+     * this pointer. */
+#if 0 // See https://bugzilla.mozilla.org/show_bug.cgi?id=1590902
+    hr = device->Activate(__uuidof(IAudioClient3),
+                          CLSCTX_INPROC_SERVER,
+                          NULL, audio_client.receive_vpp());
+    if (hr == E_NOINTERFACE) {
+#endif
+    hr = device->Activate(__uuidof(IAudioClient), CLSCTX_INPROC_SERVER, NULL,
+                          audio_client.receive_vpp());
+#if 0
+    }
+#endif
+
+    if (FAILED(hr)) {
+      LOG("Could not activate the device to get an audio"
+          " client for %s: error: %lx\n",
+          DIRECTION_NAME, hr);
+      // A particular device can't be activated because it has been
+      // unplugged, try fall back to the default audio device.
+      if (devid && hr == AUDCLNT_E_DEVICE_INVALIDATED && allow_fallback) {
+        LOG("Trying again with the default %s audio device.", DIRECTION_NAME);
+        devid = nullptr;
+        device = nullptr;
+        try_again = true;
+      } else {
+        return CUBEB_ERROR;
+      }
+    } else {
+      try_again = false;
+    }
+  } while (try_again);
+
+  /* We have to distinguish between the format the mixer uses,
+   * and the format the stream we want to play uses. */
+  WAVEFORMATEX * tmp = nullptr;
+  hr = audio_client->GetMixFormat(&tmp);
+  if (FAILED(hr)) {
+    LOG("Could not fetch current mix format from the audio"
+        " client for %s: error: %lx",
+        DIRECTION_NAME, hr);
+    return CUBEB_ERROR;
+  }
+  com_heap_ptr<WAVEFORMATEX> mix_format(tmp);
+
+  mix_format->wBitsPerSample = stm->bytes_per_sample * 8;
+  if (mix_format->wFormatTag == WAVE_FORMAT_PCM ||
+      mix_format->wFormatTag == WAVE_FORMAT_IEEE_FLOAT) {
+    switch (mix_format->wBitsPerSample) {
+    case 8:
+    case 16:
+      mix_format->wFormatTag = WAVE_FORMAT_PCM;
+      break;
+    case 32:
+      mix_format->wFormatTag = WAVE_FORMAT_IEEE_FLOAT;
+      break;
+    default:
+      LOG("%u bits per sample is incompatible with PCM wave formats",
+          mix_format->wBitsPerSample);
+      return CUBEB_ERROR;
+    }
+  }
+
+  if (mix_format->wFormatTag == WAVE_FORMAT_EXTENSIBLE) {
+    WAVEFORMATEXTENSIBLE * format_pcm =
+        reinterpret_cast<WAVEFORMATEXTENSIBLE *>(mix_format.get());
+    format_pcm->SubFormat = stm->waveformatextensible_sub_format;
+  }
+  waveformatex_update_derived_properties(mix_format.get());
+
+  /* Set channel layout only when there're more than two channels. Otherwise,
+   * use the default setting retrieved from the stream format of the audio
+   * engine's internal processing by GetMixFormat. */
+  if (mix_format->nChannels > 2) {
+    handle_channel_layout(stm, direction, mix_format, stream_params);
+  }
+
+  mix_params->format = stream_params->format;
+  mix_params->rate = mix_format->nSamplesPerSec;
+  mix_params->channels = mix_format->nChannels;
+  mix_params->layout = mask_to_channel_layout(mix_format.get());
+
+  LOG("Setup requested=[f=%d r=%u c=%u l=%u] mix=[f=%d r=%u c=%u l=%u]",
+      stream_params->format, stream_params->rate, stream_params->channels,
+      stream_params->layout, mix_params->format, mix_params->rate,
+      mix_params->channels, mix_params->layout);
+
+  DWORD flags = 0;
+
+  // Check if a loopback device should be requested. Note that event callbacks
+  // do not work with loopback devices, so only request these if not looping.
+  if (is_loopback) {
+    flags |= AUDCLNT_STREAMFLAGS_LOOPBACK;
+  } else {
+    flags |= AUDCLNT_STREAMFLAGS_EVENTCALLBACK;
+  }
+
+  REFERENCE_TIME latency_hns = frames_to_hns(stream_params->rate, stm->latency);
+
+  // Adjust input latency and check if input is using bluetooth handsfree
+  // protocol.
+  if (direction == eCapture) {
+    stm->input_bluetooth_handsfree = false;
+
+    wasapi_default_devices default_devices(stm->device_enumerator.get());
+    cubeb_device_info device_info;
+    if (wasapi_create_device(stm->context, device_info,
+                             stm->device_enumerator.get(), device.get(),
+                             &default_devices) == CUBEB_OK) {
+      if (device_info.latency_hi == 0) {
+        LOG("Input: could not query latency_hi to guess safe latency");
+        wasapi_destroy_device(&device_info);
+        return CUBEB_ERROR;
+      }
+      // This multiplicator has been found empirically.
+      uint32_t latency_frames = device_info.latency_hi * 8;
+      LOG("Input: latency increased to %u frames from a default of %u",
+          latency_frames, device_info.latency_hi);
+      latency_hns = frames_to_hns(device_info.default_rate, latency_frames);
+
+      const char * HANDSFREE_TAG = "BTHHFENUM";
+      size_t len = sizeof(HANDSFREE_TAG);
+      if (strlen(device_info.group_id) >= len &&
+          strncmp(device_info.group_id, HANDSFREE_TAG, len) == 0) {
+        LOG("Input device is using bluetooth handsfree protocol");
+        stm->input_bluetooth_handsfree = true;
+      }
+
+      wasapi_destroy_device(&device_info);
+    } else {
+      LOG("Could not get cubeb_device_info. Skip customizing input settings");
+    }
+  }
+
+  if (stream_params->prefs & CUBEB_STREAM_PREF_RAW) {
+    if (initialize_iaudioclient2(audio_client) != CUBEB_OK) {
+      LOG("Can't initialize an IAudioClient2, error: %lx", GetLastError());
+      // This is not fatal.
+    }
+  }
+
+#if 0 // See https://bugzilla.mozilla.org/show_bug.cgi?id=1590902
+  if (initialize_iaudioclient3(audio_client, stm, mix_format, flags, direction)) {
+    LOG("Initialized with IAudioClient3");
+  } else {
+#endif
+  hr = audio_client->Initialize(AUDCLNT_SHAREMODE_SHARED, flags, latency_hns, 0,
+                                mix_format.get(), NULL);
+#if 0
+  }
+#endif
+  if (FAILED(hr)) {
+    LOG("Unable to initialize audio client for %s: %lx.", DIRECTION_NAME, hr);
+    return CUBEB_ERROR;
+  }
+
+  hr = audio_client->GetBufferSize(buffer_frame_count);
+  if (FAILED(hr)) {
+    LOG("Could not get the buffer size from the client"
+        " for %s %lx.",
+        DIRECTION_NAME, hr);
+    return CUBEB_ERROR;
+  }
+
+  LOG("Buffer size is: %d for %s\n", *buffer_frame_count, DIRECTION_NAME);
+
+  // Events are used if not looping back
+  if (!is_loopback) {
+    hr = audio_client->SetEventHandle(event);
+    if (FAILED(hr)) {
+      LOG("Could set the event handle for the %s client %lx.", DIRECTION_NAME,
+          hr);
+      return CUBEB_ERROR;
+    }
+  }
+
+  hr = audio_client->GetService(riid, render_or_capture_client.receive_vpp());
+  if (FAILED(hr)) {
+    LOG("Could not get the %s client %lx.", DIRECTION_NAME, hr);
+    return CUBEB_ERROR;
+  }
+
+  return CUBEB_OK;
+}
+
+#undef DIRECTION_NAME
+
+// Returns a non-null cubeb_devid if we find a matched device, or nullptr
+// otherwise.
+cubeb_devid
+wasapi_find_bt_handsfree_output_device(cubeb_stream * stm)
+{
+  HRESULT hr;
+  cubeb_device_info * input_device = nullptr;
+  cubeb_device_collection collection;
+
+  // Only try to match to an output device if the input device is a bluetooth
+  // device that is using the handsfree protocol
+  if (!stm->input_bluetooth_handsfree) {
+    return nullptr;
+  }
+
+  wchar_t * tmp = nullptr;
+  hr = stm->input_device->GetId(&tmp);
+  if (FAILED(hr)) {
+    LOG("Couldn't get input device id in "
+        "wasapi_find_bt_handsfree_output_device");
+    return nullptr;
+  }
+  com_heap_ptr<wchar_t> device_id(tmp);
+  cubeb_devid input_device_id = reinterpret_cast<cubeb_devid>(
+      intern_device_id(stm->context, device_id.get()));
+  if (!input_device_id) {
+    return nullptr;
+  }
+
+  int rv = wasapi_enumerate_devices_internal(
+      stm->context,
+      (cubeb_device_type)(CUBEB_DEVICE_TYPE_INPUT | CUBEB_DEVICE_TYPE_OUTPUT),
+      &collection, DEVICE_STATE_ACTIVE);
+  if (rv != CUBEB_OK) {
+    return nullptr;
+  }
+
+  // Find the input device, and then find the output device with the same group
+  // id and the same rate.
+  for (uint32_t i = 0; i < collection.count; i++) {
+    if (collection.device[i].devid == input_device_id) {
+      input_device = &collection.device[i];
+      break;
+    }
+  }
+
+  cubeb_devid matched_output = nullptr;
+
+  if (input_device) {
+    for (uint32_t i = 0; i < collection.count; i++) {
+      cubeb_device_info & dev = collection.device[i];
+      if (dev.type == CUBEB_DEVICE_TYPE_OUTPUT && dev.group_id &&
+          !strcmp(dev.group_id, input_device->group_id) &&
+          dev.default_rate == input_device->default_rate) {
+        LOG("Found matching device for %s: %s", input_device->friendly_name,
+            dev.friendly_name);
+        matched_output = dev.devid;
+        break;
+      }
+    }
+  }
+
+  wasapi_device_collection_destroy(stm->context, &collection);
+  return matched_output;
+}
+
+std::unique_ptr<wchar_t[]>
+copy_wide_string(const wchar_t * src)
+{
+  XASSERT(src);
+  size_t len = wcslen(src);
+  std::unique_ptr<wchar_t[]> copy(new wchar_t[len + 1]);
+  if (wcsncpy_s(copy.get(), len + 1, src, len) != 0) {
+    return nullptr;
+  }
+  return copy;
+}
+
+int
+setup_wasapi_stream(cubeb_stream * stm)
+{
+  int rv;
+
+  stm->stream_reset_lock.assert_current_thread_owns();
+
+  XASSERT((!stm->output_client || !stm->input_client) &&
+          "WASAPI stream already setup, close it first.");
+
+  std::unique_ptr<const wchar_t[]> selected_output_device_id;
+  if (stm->output_device_id) {
+    if (std::unique_ptr<wchar_t[]> tmp =
+            copy_wide_string(stm->output_device_id.get())) {
+      selected_output_device_id = std::move(tmp);
+    } else {
+      LOG("Failed to copy output device identifier.");
+      return CUBEB_ERROR;
+    }
+  }
+
+  if (has_input(stm)) {
+    LOG("(%p) Setup capture: device=%p", stm, stm->input_device_id.get());
+    rv = setup_wasapi_stream_one_side(
+        stm, &stm->input_stream_params, stm->input_device_id.get(), eCapture,
+        __uuidof(IAudioCaptureClient), stm->input_client,
+        &stm->input_buffer_frame_count, stm->input_available_event,
+        stm->capture_client, &stm->input_mix_params, stm->input_device);
+    if (rv != CUBEB_OK) {
+      LOG("Failure to open the input side.");
+      return rv;
+    }
+
+    // We initializing an input stream, buffer ahead two buffers worth of
+    // silence. This delays the input side slightly, but allow to not glitch
+    // when no input is available when calling into the resampler to call the
+    // callback: the input refill event will be set shortly after to compensate
+    // for this lack of data. In debug, four buffers are used, to avoid tripping
+    // up assertions down the line.
+#if !defined(DEBUG)
+    const int silent_buffer_count = 2;
+#else
+    const int silent_buffer_count = 6;
+#endif
+    stm->linear_input_buffer->push_silence(stm->input_buffer_frame_count *
+                                           stm->input_stream_params.channels *
+                                           silent_buffer_count);
+
+    // If this is a bluetooth device, and the output device is the default
+    // device, and the default device is the same bluetooth device, pick the
+    // right output device, running at the same rate and with the same protocol
+    // as the input.
+    if (!selected_output_device_id) {
+      cubeb_devid matched = wasapi_find_bt_handsfree_output_device(stm);
+      if (matched) {
+        selected_output_device_id =
+            utf8_to_wstr(reinterpret_cast<char const *>(matched));
+      }
+    }
+  }
+
+  // If we don't have an output device but are requesting a loopback device,
+  // we attempt to open that same device in output mode in order to drive the
+  // loopback via the output events.
+  stm->has_dummy_output = false;
+  if (!has_output(stm) &&
+      stm->input_stream_params.prefs & CUBEB_STREAM_PREF_LOOPBACK) {
+    stm->output_stream_params.rate = stm->input_stream_params.rate;
+    stm->output_stream_params.channels = stm->input_stream_params.channels;
+    stm->output_stream_params.layout = stm->input_stream_params.layout;
+    if (stm->input_device_id) {
+      if (std::unique_ptr<wchar_t[]> tmp =
+              copy_wide_string(stm->input_device_id.get())) {
+        XASSERT(!selected_output_device_id);
+        selected_output_device_id = std::move(tmp);
+      } else {
+        LOG("Failed to copy device identifier while copying input stream "
+            "configuration to output stream configuration to drive loopback.");
+        return CUBEB_ERROR;
+      }
+    }
+    stm->has_dummy_output = true;
+  }
+
+  if (has_output(stm)) {
+    LOG("(%p) Setup render: device=%p", stm, selected_output_device_id.get());
+    rv = setup_wasapi_stream_one_side(
+        stm, &stm->output_stream_params, selected_output_device_id.get(),
+        eRender, __uuidof(IAudioRenderClient), stm->output_client,
+        &stm->output_buffer_frame_count, stm->refill_event, stm->render_client,
+        &stm->output_mix_params, stm->output_device);
+    if (rv != CUBEB_OK) {
+      LOG("Failure to open the output side.");
+      return rv;
+    }
+
+    HRESULT hr = 0;
+#ifdef CUBEB_WASAPI_USE_IAUDIOSTREAMVOLUME
+    hr = stm->output_client->GetService(__uuidof(IAudioStreamVolume),
+                                        stm->audio_stream_volume.receive_vpp());
+    if (FAILED(hr)) {
+      LOG("Could not get the IAudioStreamVolume: %lx", hr);
+      return CUBEB_ERROR;
+    }
+#endif
+
+    XASSERT(stm->frames_written == 0);
+    hr = stm->output_client->GetService(__uuidof(IAudioClock),
+                                        stm->audio_clock.receive_vpp());
+    if (FAILED(hr)) {
+      LOG("Could not get the IAudioClock: %lx", hr);
+      return CUBEB_ERROR;
+    }
+
+#ifdef CUBEB_WASAPI_USE_IAUDIOSTREAMVOLUME
+    /* Restore the stream volume over a device change. */
+    if (stream_set_volume(stm, stm->volume) != CUBEB_OK) {
+      LOG("Could not set the volume.");
+      return CUBEB_ERROR;
+    }
+#endif
+  }
+
+  /* If we have both input and output, we resample to
+   * the highest sample rate available. */
+  int32_t target_sample_rate;
+  if (has_input(stm) && has_output(stm)) {
+    XASSERT(stm->input_stream_params.rate == stm->output_stream_params.rate);
+    target_sample_rate = stm->input_stream_params.rate;
+  } else if (has_input(stm)) {
+    target_sample_rate = stm->input_stream_params.rate;
+  } else {
+    XASSERT(has_output(stm));
+    target_sample_rate = stm->output_stream_params.rate;
+  }
+
+  LOG("Target sample rate: %d", target_sample_rate);
+
+  /* If we are playing/capturing a mono stream, we only resample one channel,
+   and copy it over, so we are always resampling the number
+   of channels of the stream, not the number of channels
+   that WASAPI wants. */
+  cubeb_stream_params input_params = stm->input_mix_params;
+  input_params.channels = stm->input_stream_params.channels;
+  cubeb_stream_params output_params = stm->output_mix_params;
+  output_params.channels = stm->output_stream_params.channels;
+
+  stm->resampler.reset(cubeb_resampler_create(
+      stm, has_input(stm) ? &input_params : nullptr,
+      has_output(stm) && !stm->has_dummy_output ? &output_params : nullptr,
+      target_sample_rate, wasapi_data_callback, stm->user_ptr,
+      stm->voice ? CUBEB_RESAMPLER_QUALITY_VOIP
+                 : CUBEB_RESAMPLER_QUALITY_DESKTOP,
+      CUBEB_RESAMPLER_RECLOCK_NONE));
+  if (!stm->resampler) {
+    LOG("Could not get a resampler");
+    return CUBEB_ERROR;
+  }
+
+  XASSERT(has_input(stm) || has_output(stm));
+
+  if (has_input(stm) && has_output(stm)) {
+    stm->refill_callback = refill_callback_duplex;
+  } else if (has_input(stm)) {
+    stm->refill_callback = refill_callback_input;
+  } else if (has_output(stm)) {
+    stm->refill_callback = refill_callback_output;
+  }
+
+  // Create input mixer.
+  if (has_input(stm) &&
+      ((stm->input_mix_params.layout != CUBEB_LAYOUT_UNDEFINED &&
+        stm->input_mix_params.layout != stm->input_stream_params.layout) ||
+       (stm->input_mix_params.channels != stm->input_stream_params.channels))) {
+    if (stm->input_mix_params.layout == CUBEB_LAYOUT_UNDEFINED) {
+      LOG("Input stream using undefined layout! Any mixing may be "
+          "unpredictable!\n");
+    }
+    stm->input_mixer.reset(cubeb_mixer_create(
+        stm->input_stream_params.format, stm->input_mix_params.channels,
+        stm->input_mix_params.layout, stm->input_stream_params.channels,
+        stm->input_stream_params.layout));
+    assert(stm->input_mixer);
+  }
+
+  // Create output mixer.
+  if (has_output(stm) &&
+      stm->output_mix_params.layout != stm->output_stream_params.layout) {
+    if (stm->output_mix_params.layout == CUBEB_LAYOUT_UNDEFINED) {
+      LOG("Output stream using undefined layout! Any mixing may be "
+          "unpredictable!\n");
+    }
+    stm->output_mixer.reset(cubeb_mixer_create(
+        stm->output_stream_params.format, stm->output_stream_params.channels,
+        stm->output_stream_params.layout, stm->output_mix_params.channels,
+        stm->output_mix_params.layout));
+    assert(stm->output_mixer);
+    // Input is up/down mixed when depacketized in get_input_buffer.
+    stm->mix_buffer.resize(
+        frames_to_bytes_before_mix(stm, stm->output_buffer_frame_count));
+  }
+
+  return CUBEB_OK;
+}
+
+ERole
+pref_to_role(cubeb_stream_prefs prefs)
+{
+  if (prefs & CUBEB_STREAM_PREF_VOICE) {
+    return eCommunications;
+  }
+
+  return eConsole;
+}
+
+int
+wasapi_stream_init(cubeb * context, cubeb_stream ** stream,
+                   char const * stream_name, cubeb_devid input_device,
+                   cubeb_stream_params * input_stream_params,
+                   cubeb_devid output_device,
+                   cubeb_stream_params * output_stream_params,
+                   unsigned int latency_frames,
+                   cubeb_data_callback data_callback,
+                   cubeb_state_callback state_callback, void * user_ptr)
+{
+  int rv;
+
+  XASSERT(context && stream && (input_stream_params || output_stream_params));
+
+  if (output_stream_params && input_stream_params &&
+      output_stream_params->format != input_stream_params->format) {
+    return CUBEB_ERROR_INVALID_FORMAT;
+  }
+
+  cubeb_stream * stm = new cubeb_stream();
+  auto_stream_ref stream_ref(stm);
+
+  stm->context = context;
+  stm->data_callback = data_callback;
+  stm->state_callback = state_callback;
+  stm->user_ptr = user_ptr;
+  stm->role = eConsole;
+  stm->input_bluetooth_handsfree = false;
+
+  HRESULT hr =
+      CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL, CLSCTX_INPROC_SERVER,
+                       IID_PPV_ARGS(stm->device_enumerator.receive()));
+  if (FAILED(hr)) {
+    LOG("Could not get device enumerator: %lx", hr);
+    return hr;
+  }
+
+  if (input_stream_params) {
+    stm->input_stream_params = *input_stream_params;
+    stm->input_device_id =
+        utf8_to_wstr(reinterpret_cast<char const *>(input_device));
+  }
+  if (output_stream_params) {
+    stm->output_stream_params = *output_stream_params;
+    stm->output_device_id =
+        utf8_to_wstr(reinterpret_cast<char const *>(output_device));
+  }
+
+  if (stm->output_stream_params.prefs & CUBEB_STREAM_PREF_VOICE ||
+      stm->input_stream_params.prefs & CUBEB_STREAM_PREF_VOICE) {
+    stm->voice = true;
+  } else {
+    stm->voice = false;
+  }
+
+  switch (output_stream_params ? output_stream_params->format
+                               : input_stream_params->format) {
+  case CUBEB_SAMPLE_S16NE:
+    stm->bytes_per_sample = sizeof(short);
+    stm->waveformatextensible_sub_format = KSDATAFORMAT_SUBTYPE_PCM;
+    stm->linear_input_buffer.reset(new auto_array_wrapper_impl<short>);
+    break;
+  case CUBEB_SAMPLE_FLOAT32NE:
+    stm->bytes_per_sample = sizeof(float);
+    stm->waveformatextensible_sub_format = KSDATAFORMAT_SUBTYPE_IEEE_FLOAT;
+    stm->linear_input_buffer.reset(new auto_array_wrapper_impl<float>);
+    break;
+  default:
+    return CUBEB_ERROR_INVALID_FORMAT;
+  }
+
+  stm->latency = latency_frames;
+
+  stm->reconfigure_event = CreateEvent(NULL, 0, 0, NULL);
+  if (!stm->reconfigure_event) {
+    LOG("Can't create the reconfigure event, error: %lx", GetLastError());
+    return CUBEB_ERROR;
+  }
+
+  /* Unconditionally create the two events so that the wait logic is simpler. */
+  stm->refill_event = CreateEvent(NULL, 0, 0, NULL);
+  if (!stm->refill_event) {
+    LOG("Can't create the refill event, error: %lx", GetLastError());
+    return CUBEB_ERROR;
+  }
+
+  stm->input_available_event = CreateEvent(NULL, 0, 0, NULL);
+  if (!stm->input_available_event) {
+    LOG("Can't create the input available event , error: %lx", GetLastError());
+    return CUBEB_ERROR;
+  }
+
+  stm->shutdown_event = CreateEvent(NULL, 0, 0, NULL);
+  if (!stm->shutdown_event) {
+    LOG("Can't create the shutdown event, error: %lx", GetLastError());
+    return CUBEB_ERROR;
+  }
+
+  stm->thread_ready_event = CreateEvent(NULL, 0, 0, NULL);
+  if (!stm->thread_ready_event) {
+    LOG("Can't create the thread ready event, error: %lx", GetLastError());
+    return CUBEB_ERROR;
+  }
+
+  {
+    /* Locking here is not strictly necessary, because we don't have a
+       notification client that can reset the stream yet, but it lets us
+       assert that the lock is held in the function. */
+    auto_lock lock(stm->stream_reset_lock);
+    rv = setup_wasapi_stream(stm);
+  }
+  if (rv != CUBEB_OK) {
+    return rv;
+  }
+
+  // Follow the system default devices when not specifying devices explicitly
+  // and CUBEB_STREAM_PREF_DISABLE_DEVICE_SWITCHING is not set.
+  if ((!input_device && input_stream_params &&
+       !(input_stream_params->prefs &
+         CUBEB_STREAM_PREF_DISABLE_DEVICE_SWITCHING)) ||
+      (!output_device && output_stream_params &&
+       !(output_stream_params->prefs &
+         CUBEB_STREAM_PREF_DISABLE_DEVICE_SWITCHING))) {
+    LOG("Follow the system default input or/and output devices");
+    HRESULT hr = register_notification_client(stm);
+    if (FAILED(hr)) {
+      /* this is not fatal, we can still play audio, but we won't be able
+         to keep using the default audio endpoint if it changes. */
+      LOG("failed to register notification client, %lx", hr);
+    }
+  }
+
+  cubeb_async_log_reset_threads();
+  stm->thread =
+      (HANDLE)_beginthreadex(NULL, 512 * 1024, wasapi_stream_render_loop, stm,
+                             STACK_SIZE_PARAM_IS_A_RESERVATION, NULL);
+  if (stm->thread == NULL) {
+    LOG("could not create WASAPI render thread.");
+    return CUBEB_ERROR;
+  }
+
+  // Wait for the wasapi_stream_render_loop thread to signal that COM has been
+  // initialized and the stream's ref_count has been incremented.
+  hr = WaitForSingleObject(stm->thread_ready_event, INFINITE);
+  XASSERT(hr == WAIT_OBJECT_0);
+  CloseHandle(stm->thread_ready_event);
+  stm->thread_ready_event = 0;
+
+  wasapi_stream_add_ref(stm);
+  *stream = stm;
+
+  LOG("Stream init successful (%p)", *stream);
+  return CUBEB_OK;
+}
+
+void
+close_wasapi_stream(cubeb_stream * stm)
+{
+  XASSERT(stm);
+
+  stm->stream_reset_lock.assert_current_thread_owns();
+
+#ifdef CUBEB_WASAPI_USE_IAUDIOSTREAMVOLUME
+  stm->audio_stream_volume = nullptr;
+#endif
+  stm->audio_clock = nullptr;
+  stm->render_client = nullptr;
+  stm->output_client = nullptr;
+  stm->output_device = nullptr;
+
+  stm->capture_client = nullptr;
+  stm->input_client = nullptr;
+  stm->input_device = nullptr;
+
+  stm->total_frames_written += static_cast<UINT64>(
+      round(stm->frames_written *
+            stream_to_mix_samplerate_ratio(stm->output_stream_params,
+                                           stm->output_mix_params)));
+  stm->frames_written = 0;
+
+  stm->resampler.reset();
+  stm->output_mixer.reset();
+  stm->input_mixer.reset();
+  stm->mix_buffer.clear();
+  if (stm->linear_input_buffer) {
+    stm->linear_input_buffer->clear();
+  }
+}
+
+LONG
+wasapi_stream_add_ref(cubeb_stream * stm)
+{
+  XASSERT(stm);
+  LONG result = InterlockedIncrement(&stm->ref_count);
+  LOGV("Stream ref count incremented = %i (%p)", result, stm);
+  return result;
+}
+
+LONG
+wasapi_stream_release(cubeb_stream * stm)
+{
+  XASSERT(stm);
+
+  LONG result = InterlockedDecrement(&stm->ref_count);
+  LOGV("Stream ref count decremented = %i (%p)", result, stm);
+  if (result == 0) {
+    LOG("Stream ref count hit zero, destroying (%p)", stm);
+
+    if (stm->notification_client) {
+      unregister_notification_client(stm);
+    }
+
+    CloseHandle(stm->shutdown_event);
+    CloseHandle(stm->reconfigure_event);
+    CloseHandle(stm->refill_event);
+    CloseHandle(stm->input_available_event);
+
+    CloseHandle(stm->thread);
+
+    // The variables intialized in wasapi_stream_init,
+    // must be destroyed in wasapi_stream_release.
+    stm->linear_input_buffer.reset();
+
+    {
+      auto_lock lock(stm->stream_reset_lock);
+      close_wasapi_stream(stm);
+    }
+
+    delete stm;
+  }
+
+  return result;
+}
+
+void
+wasapi_stream_destroy(cubeb_stream * stm)
+{
+  XASSERT(stm);
+  LOG("Stream destroy called, decrementing ref count (%p)", stm);
+
+  stop_and_join_render_thread(stm);
+  wasapi_stream_release(stm);
+}
+
+enum StreamDirection { OUTPUT, INPUT };
+
+int
+stream_start_one_side(cubeb_stream * stm, StreamDirection dir)
+{
+  XASSERT(stm);
+  XASSERT((dir == OUTPUT && stm->output_client) ||
+          (dir == INPUT && stm->input_client));
+
+  HRESULT hr =
+      dir == OUTPUT ? stm->output_client->Start() : stm->input_client->Start();
+  if (hr == AUDCLNT_E_DEVICE_INVALIDATED) {
+    LOG("audioclient invalidated for %s device, reconfiguring",
+        dir == OUTPUT ? "output" : "input");
+
+    BOOL ok = ResetEvent(stm->reconfigure_event);
+    if (!ok) {
+      LOG("resetting reconfig event failed for %s stream: %lx",
+          dir == OUTPUT ? "output" : "input", GetLastError());
+    }
+
+    close_wasapi_stream(stm);
+    int r = setup_wasapi_stream(stm);
+    if (r != CUBEB_OK) {
+      LOG("reconfigure failed");
+      return r;
+    }
+
+    HRESULT hr2 = dir == OUTPUT ? stm->output_client->Start()
+                                : stm->input_client->Start();
+    if (FAILED(hr2)) {
+      LOG("could not start the %s stream after reconfig: %lx",
+          dir == OUTPUT ? "output" : "input", hr);
+      return CUBEB_ERROR;
+    }
+  } else if (FAILED(hr)) {
+    LOG("could not start the %s stream: %lx.",
+        dir == OUTPUT ? "output" : "input", hr);
+    return CUBEB_ERROR;
+  }
+
+  return CUBEB_OK;
+}
+
+int
+wasapi_stream_start(cubeb_stream * stm)
+{
+  auto_lock lock(stm->stream_reset_lock);
+
+  XASSERT(stm);
+  XASSERT(stm->output_client || stm->input_client);
+
+  if (stm->output_client) {
+    int rv = stream_start_one_side(stm, OUTPUT);
+    if (rv != CUBEB_OK) {
+      return rv;
+    }
+  }
+
+  if (stm->input_client) {
+    int rv = stream_start_one_side(stm, INPUT);
+    if (rv != CUBEB_OK) {
+      return rv;
+    }
+  }
+
+  stm->active = true;
+
+  stm->state_callback(stm, stm->user_ptr, CUBEB_STATE_STARTED);
+
+  return CUBEB_OK;
+}
+
+int
+wasapi_stream_stop(cubeb_stream * stm)
+{
+  XASSERT(stm);
+  HRESULT hr;
+
+  {
+    auto_lock lock(stm->stream_reset_lock);
+
+    if (stm->output_client) {
+      hr = stm->output_client->Stop();
+      if (FAILED(hr)) {
+        LOG("could not stop AudioClient (output)");
+        return CUBEB_ERROR;
+      }
+    }
+
+    if (stm->input_client) {
+      hr = stm->input_client->Stop();
+      if (FAILED(hr)) {
+        LOG("could not stop AudioClient (input)");
+        return CUBEB_ERROR;
+      }
+    }
+
+    stm->active = false;
+
+    wasapi_state_callback(stm, stm->user_ptr, CUBEB_STATE_STOPPED);
+  }
+
+  return CUBEB_OK;
+}
+
+int
+wasapi_stream_get_position(cubeb_stream * stm, uint64_t * position)
+{
+  XASSERT(stm && position);
+  auto_lock lock(stm->stream_reset_lock);
+
+  if (!has_output(stm)) {
+    return CUBEB_ERROR;
+  }
+
+  /* Calculate how far behind the current stream head the playback cursor is. */
+  uint64_t stream_delay = static_cast<uint64_t>(current_stream_delay(stm) *
+                                                stm->output_stream_params.rate);
+
+  /* Calculate the logical stream head in frames at the stream sample rate. */
+  uint64_t max_pos =
+      stm->total_frames_written +
+      static_cast<uint64_t>(
+          round(stm->frames_written *
+                stream_to_mix_samplerate_ratio(stm->output_stream_params,
+                                               stm->output_mix_params)));
+
+  *position = max_pos;
+  if (stream_delay <= *position) {
+    *position -= stream_delay;
+  }
+
+  if (*position < stm->prev_position) {
+    *position = stm->prev_position;
+  }
+  stm->prev_position = *position;
+
+  return CUBEB_OK;
+}
+
+int
+wasapi_stream_get_latency(cubeb_stream * stm, uint32_t * latency)
+{
+  XASSERT(stm && latency);
+
+  if (!has_output(stm)) {
+    return CUBEB_ERROR;
+  }
+
+  auto_lock lock(stm->stream_reset_lock);
+
+  /* The GetStreamLatency method only works if the
+     AudioClient has been initialized. */
+  if (!stm->output_client) {
+    LOG("get_latency: No output_client.");
+    return CUBEB_ERROR;
+  }
+
+  REFERENCE_TIME latency_hns;
+  HRESULT hr = stm->output_client->GetStreamLatency(&latency_hns);
+  if (FAILED(hr)) {
+    LOG("GetStreamLatency failed %lx.", hr);
+    return CUBEB_ERROR;
+  }
+  // This happens on windows 10: no error, but always 0 for latency.
+  if (latency_hns == 0) {
+    LOG("GetStreamLatency returned 0, using workaround.");
+    double delay_s = current_stream_delay(stm);
+    // convert to sample-frames
+    *latency = delay_s * stm->output_stream_params.rate;
+  } else {
+    *latency = hns_to_frames(stm, latency_hns);
+  }
+
+  LOG("Output latency %u frames.", *latency);
+
+  return CUBEB_OK;
+}
+
+int
+wasapi_stream_get_input_latency(cubeb_stream * stm, uint32_t * latency)
+{
+  XASSERT(stm && latency);
+
+  if (!has_input(stm)) {
+    LOG("Input latency queried on an output-only stream.");
+    return CUBEB_ERROR;
+  }
+
+  auto_lock lock(stm->stream_reset_lock);
+
+  if (stm->input_latency_hns == LATENCY_NOT_AVAILABLE_YET) {
+    LOG("Input latency not available yet.");
+    return CUBEB_ERROR;
+  }
+
+  *latency = hns_to_frames(stm, stm->input_latency_hns);
+
+  return CUBEB_OK;
+}
+
+int
+wasapi_stream_set_volume(cubeb_stream * stm, float volume)
+{
+  auto_lock lock(stm->stream_reset_lock);
+
+  if (!has_output(stm)) {
+    return CUBEB_ERROR;
+  }
+
+#ifdef CUBEB_WASAPI_USE_IAUDIOSTREAMVOLUME
+  if (stream_set_volume(stm, volume) != CUBEB_OK) {
+    return CUBEB_ERROR;
+  }
+#endif
+
+  stm->volume = volume;
+
+  return CUBEB_OK;
+}
+
+static char const *
+wstr_to_utf8(LPCWSTR str)
+{
+  int size = ::WideCharToMultiByte(CP_UTF8, 0, str, -1, nullptr, 0, NULL, NULL);
+  if (size <= 0) {
+    return nullptr;
+  }
+
+  char * ret = static_cast<char *>(malloc(size));
+  ::WideCharToMultiByte(CP_UTF8, 0, str, -1, ret, size, NULL, NULL);
+  return ret;
+}
+
+static std::unique_ptr<wchar_t const[]>
+utf8_to_wstr(char const * str)
+{
+  int size = ::MultiByteToWideChar(CP_UTF8, 0, str, -1, nullptr, 0);
+  if (size <= 0) {
+    return nullptr;
+  }
+
+  std::unique_ptr<wchar_t[]> ret(new wchar_t[size]);
+  ::MultiByteToWideChar(CP_UTF8, 0, str, -1, ret.get(), size);
+  return ret;
+}
+
+static com_ptr<IMMDevice>
+wasapi_get_device_node(IMMDeviceEnumerator * enumerator, IMMDevice * dev)
+{
+  com_ptr<IMMDevice> ret;
+  com_ptr<IDeviceTopology> devtopo;
+  com_ptr<IConnector> connector;
+
+  if (SUCCEEDED(dev->Activate(__uuidof(IDeviceTopology), CLSCTX_ALL, NULL,
+                              devtopo.receive_vpp())) &&
+      SUCCEEDED(devtopo->GetConnector(0, connector.receive()))) {
+    wchar_t * tmp = nullptr;
+    if (SUCCEEDED(connector->GetDeviceIdConnectedTo(&tmp))) {
+      com_heap_ptr<wchar_t> filterid(tmp);
+      if (FAILED(enumerator->GetDevice(filterid.get(), ret.receive())))
+        ret = NULL;
+    }
+  }
+
+  return ret;
+}
+
+static com_heap_ptr<wchar_t>
+wasapi_get_default_device_id(EDataFlow flow, ERole role,
+                             IMMDeviceEnumerator * enumerator)
+{
+  com_ptr<IMMDevice> dev;
+
+  HRESULT hr = enumerator->GetDefaultAudioEndpoint(flow, role, dev.receive());
+  if (SUCCEEDED(hr)) {
+    wchar_t * tmp = nullptr;
+    if (SUCCEEDED(dev->GetId(&tmp))) {
+      com_heap_ptr<wchar_t> devid(tmp);
+      return devid;
+    }
+  }
+
+  return nullptr;
+}
+
+/* `ret` must be deallocated with `wasapi_destroy_device`, iff the return value
+ * of this function is `CUBEB_OK`. */
+int
+wasapi_create_device(cubeb * ctx, cubeb_device_info & ret,
+                     IMMDeviceEnumerator * enumerator, IMMDevice * dev,
+                     wasapi_default_devices * defaults)
+{
+  com_ptr<IMMEndpoint> endpoint;
+  com_ptr<IMMDevice> devnode;
+  com_ptr<IAudioClient> client;
+  EDataFlow flow;
+  DWORD state = DEVICE_STATE_NOTPRESENT;
+  com_ptr<IPropertyStore> propstore;
+  REFERENCE_TIME def_period, min_period;
+  HRESULT hr;
+
+  XASSERT(enumerator && dev && defaults);
+
+  // zero-out to be able to safely delete the pointers to friendly_name and
+  // group_id at all time in this function.
+  PodZero(&ret, 1);
+
+  struct prop_variant : public PROPVARIANT {
+    prop_variant() { PropVariantInit(this); }
+    ~prop_variant() { PropVariantClear(this); }
+    prop_variant(prop_variant const &) = delete;
+    prop_variant & operator=(prop_variant const &) = delete;
+  };
+
+  hr = dev->QueryInterface(IID_PPV_ARGS(endpoint.receive()));
+  if (FAILED(hr)) {
+    wasapi_destroy_device(&ret);
+    return CUBEB_ERROR;
+  }
+
+  hr = endpoint->GetDataFlow(&flow);
+  if (FAILED(hr)) {
+    wasapi_destroy_device(&ret);
+    return CUBEB_ERROR;
+  }
+
+  wchar_t * tmp = nullptr;
+  hr = dev->GetId(&tmp);
+  if (FAILED(hr)) {
+    wasapi_destroy_device(&ret);
+    return CUBEB_ERROR;
+  }
+  com_heap_ptr<wchar_t> device_id(tmp);
+
+  char const * device_id_intern = intern_device_id(ctx, device_id.get());
+  if (!device_id_intern) {
+    wasapi_destroy_device(&ret);
+    return CUBEB_ERROR;
+  }
+
+  hr = dev->OpenPropertyStore(STGM_READ, propstore.receive());
+  if (FAILED(hr)) {
+    wasapi_destroy_device(&ret);
+    return CUBEB_ERROR;
+  }
+
+  hr = dev->GetState(&state);
+  if (FAILED(hr)) {
+    wasapi_destroy_device(&ret);
+    return CUBEB_ERROR;
+  }
+
+  ret.device_id = device_id_intern;
+  ret.devid = reinterpret_cast<cubeb_devid>(ret.device_id);
+  prop_variant namevar;
+  hr = propstore->GetValue(PKEY_Device_FriendlyName, &namevar);
+  if (SUCCEEDED(hr) && namevar.vt == VT_LPWSTR) {
+    ret.friendly_name = wstr_to_utf8(namevar.pwszVal);
+  }
+  if (!ret.friendly_name) {
+    // This is not fatal, but a valid string is expected in all cases.
+    char * empty = new char[1];
+    empty[0] = '\0';
+    ret.friendly_name = empty;
+  }
+
+  devnode = wasapi_get_device_node(enumerator, dev);
+  if (devnode) {
+    com_ptr<IPropertyStore> ps;
+    hr = devnode->OpenPropertyStore(STGM_READ, ps.receive());
+    if (FAILED(hr)) {
+      wasapi_destroy_device(&ret);
+      return CUBEB_ERROR;
+    }
+
+    prop_variant instancevar;
+    hr = ps->GetValue(PKEY_Device_InstanceId, &instancevar);
+    if (SUCCEEDED(hr) && instancevar.vt == VT_LPWSTR) {
+      ret.group_id = wstr_to_utf8(instancevar.pwszVal);
+    }
+  }
+
+  if (!ret.group_id) {
+    // This is not fatal, but a valid string is expected in all cases.
+    char * empty = new char[1];
+    empty[0] = '\0';
+    ret.group_id = empty;
+  }
+
+  ret.preferred = CUBEB_DEVICE_PREF_NONE;
+  if (defaults->is_default(flow, eConsole, device_id.get())) {
+    ret.preferred =
+        (cubeb_device_pref)(ret.preferred | CUBEB_DEVICE_PREF_MULTIMEDIA |
+                            CUBEB_DEVICE_PREF_NOTIFICATION);
+  } else if (defaults->is_default(flow, eCommunications, device_id.get())) {
+    ret.preferred =
+        (cubeb_device_pref)(ret.preferred | CUBEB_DEVICE_PREF_VOICE);
+  }
+
+  if (flow == eRender) {
+    ret.type = CUBEB_DEVICE_TYPE_OUTPUT;
+  } else if (flow == eCapture) {
+    ret.type = CUBEB_DEVICE_TYPE_INPUT;
+  }
+
+  switch (state) {
+  case DEVICE_STATE_ACTIVE:
+    ret.state = CUBEB_DEVICE_STATE_ENABLED;
+    break;
+  case DEVICE_STATE_UNPLUGGED:
+    ret.state = CUBEB_DEVICE_STATE_UNPLUGGED;
+    break;
+  default:
+    ret.state = CUBEB_DEVICE_STATE_DISABLED;
+    break;
+  };
+
+  ret.format = static_cast<cubeb_device_fmt>(CUBEB_DEVICE_FMT_F32NE |
+                                             CUBEB_DEVICE_FMT_S16NE);
+  ret.default_format = CUBEB_DEVICE_FMT_F32NE;
+  prop_variant fmtvar;
+  hr = propstore->GetValue(PKEY_AudioEngine_DeviceFormat, &fmtvar);
+  if (SUCCEEDED(hr) && fmtvar.vt == VT_BLOB) {
+    if (fmtvar.blob.cbSize == sizeof(PCMWAVEFORMAT)) {
+      const PCMWAVEFORMAT * pcm =
+          reinterpret_cast<const PCMWAVEFORMAT *>(fmtvar.blob.pBlobData);
+
+      ret.max_rate = ret.min_rate = ret.default_rate = pcm->wf.nSamplesPerSec;
+      ret.max_channels = pcm->wf.nChannels;
+    } else if (fmtvar.blob.cbSize >= sizeof(WAVEFORMATEX)) {
+      WAVEFORMATEX * wfx =
+          reinterpret_cast<WAVEFORMATEX *>(fmtvar.blob.pBlobData);
+
+      if (fmtvar.blob.cbSize >= sizeof(WAVEFORMATEX) + wfx->cbSize ||
+          wfx->wFormatTag == WAVE_FORMAT_PCM) {
+        ret.max_rate = ret.min_rate = ret.default_rate = wfx->nSamplesPerSec;
+        ret.max_channels = wfx->nChannels;
+      }
+    }
+  }
+
+  if (SUCCEEDED(dev->Activate(__uuidof(IAudioClient), CLSCTX_INPROC_SERVER,
+                              NULL, client.receive_vpp())) &&
+      SUCCEEDED(client->GetDevicePeriod(&def_period, &min_period))) {
+    ret.latency_lo = hns_to_frames(ret.default_rate, min_period);
+    ret.latency_hi = hns_to_frames(ret.default_rate, def_period);
+  } else {
+    ret.latency_lo = 0;
+    ret.latency_hi = 0;
+  }
+
+  XASSERT(ret.friendly_name && ret.group_id);
+
+  return CUBEB_OK;
+}
+
+void
+wasapi_destroy_device(cubeb_device_info * device)
+{
+  delete[] device->friendly_name;
+  delete[] device->group_id;
+}
+
+static int
+wasapi_enumerate_devices_internal(cubeb * context, cubeb_device_type type,
+                                  cubeb_device_collection * out,
+                                  DWORD state_mask)
+{
+  com_ptr<IMMDeviceEnumerator> enumerator;
+  com_ptr<IMMDeviceCollection> collection;
+  HRESULT hr;
+  UINT cc, i;
+  EDataFlow flow;
+
+  hr =
+      CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL, CLSCTX_INPROC_SERVER,
+                       IID_PPV_ARGS(enumerator.receive()));
+  if (FAILED(hr)) {
+    LOG("Could not get device enumerator: %lx", hr);
+    return CUBEB_ERROR;
+  }
+
+  wasapi_default_devices default_devices(enumerator.get());
+
+  if (type == CUBEB_DEVICE_TYPE_OUTPUT) {
+    flow = eRender;
+  } else if (type == CUBEB_DEVICE_TYPE_INPUT) {
+    flow = eCapture;
+  } else if (type & (CUBEB_DEVICE_TYPE_INPUT | CUBEB_DEVICE_TYPE_OUTPUT)) {
+    flow = eAll;
+  } else {
+    return CUBEB_ERROR;
+  }
+
+  hr = enumerator->EnumAudioEndpoints(flow, state_mask, collection.receive());
+  if (FAILED(hr)) {
+    LOG("Could not enumerate audio endpoints: %lx", hr);
+    return CUBEB_ERROR;
+  }
+
+  hr = collection->GetCount(&cc);
+  if (FAILED(hr)) {
+    LOG("IMMDeviceCollection::GetCount() failed: %lx", hr);
+    return CUBEB_ERROR;
+  }
+  cubeb_device_info * devices = new cubeb_device_info[cc];
+  if (!devices)
+    return CUBEB_ERROR;
+
+  PodZero(devices, cc);
+  out->count = 0;
+  for (i = 0; i < cc; i++) {
+    com_ptr<IMMDevice> dev;
+    hr = collection->Item(i, dev.receive());
+    if (FAILED(hr)) {
+      LOG("IMMDeviceCollection::Item(%u) failed: %lx", i - 1, hr);
+      continue;
+    }
+    if (wasapi_create_device(context, devices[out->count], enumerator.get(),
+                             dev.get(), &default_devices) == CUBEB_OK) {
+      out->count += 1;
+    }
+  }
+
+  out->device = devices;
+  return CUBEB_OK;
+}
+
+static int
+wasapi_enumerate_devices(cubeb * context, cubeb_device_type type,
+                         cubeb_device_collection * out)
+{
+  return wasapi_enumerate_devices_internal(
+      context, type, out,
+      DEVICE_STATE_ACTIVE | DEVICE_STATE_DISABLED | DEVICE_STATE_UNPLUGGED);
+}
+
+static int
+wasapi_device_collection_destroy(cubeb * /*ctx*/,
+                                 cubeb_device_collection * collection)
+{
+  XASSERT(collection);
+
+  for (size_t n = 0; n < collection->count; n++) {
+    cubeb_device_info & dev = collection->device[n];
+    wasapi_destroy_device(&dev);
+  }
+
+  delete[] collection->device;
+  return CUBEB_OK;
+}
+
+static int
+wasapi_register_device_collection_changed(
+    cubeb * context, cubeb_device_type devtype,
+    cubeb_device_collection_changed_callback collection_changed_callback,
+    void * user_ptr)
+{
+  auto_lock lock(context->lock);
+  if (devtype == CUBEB_DEVICE_TYPE_UNKNOWN) {
+    return CUBEB_ERROR_INVALID_PARAMETER;
+  }
+
+  if (collection_changed_callback) {
+    // Make sure it has been unregistered first.
+    XASSERT(((devtype & CUBEB_DEVICE_TYPE_INPUT) &&
+             !context->input_collection_changed_callback) ||
+            ((devtype & CUBEB_DEVICE_TYPE_OUTPUT) &&
+             !context->output_collection_changed_callback));
+
+    // Stop the notification client. Notifications arrive on
+    // a separate thread. We stop them here to avoid
+    // synchronization issues during the update.
+    if (context->device_collection_enumerator.get()) {
+      HRESULT hr = unregister_collection_notification_client(context);
+      if (FAILED(hr)) {
+        return CUBEB_ERROR;
+      }
+    }
+
+    if (devtype & CUBEB_DEVICE_TYPE_INPUT) {
+      context->input_collection_changed_callback = collection_changed_callback;
+      context->input_collection_changed_user_ptr = user_ptr;
+    }
+    if (devtype & CUBEB_DEVICE_TYPE_OUTPUT) {
+      context->output_collection_changed_callback = collection_changed_callback;
+      context->output_collection_changed_user_ptr = user_ptr;
+    }
+
+    HRESULT hr = register_collection_notification_client(context);
+    if (FAILED(hr)) {
+      return CUBEB_ERROR;
+    }
+  } else {
+    if (!context->device_collection_enumerator.get()) {
+      // Already unregistered, ignore it.
+      return CUBEB_OK;
+    }
+
+    HRESULT hr = unregister_collection_notification_client(context);
+    if (FAILED(hr)) {
+      return CUBEB_ERROR;
+    }
+    if (devtype & CUBEB_DEVICE_TYPE_INPUT) {
+      context->input_collection_changed_callback = nullptr;
+      context->input_collection_changed_user_ptr = nullptr;
+    }
+    if (devtype & CUBEB_DEVICE_TYPE_OUTPUT) {
+      context->output_collection_changed_callback = nullptr;
+      context->output_collection_changed_user_ptr = nullptr;
+    }
+
+    // If after the updates we still have registered
+    // callbacks restart the notification client.
+    if (context->input_collection_changed_callback ||
+        context->output_collection_changed_callback) {
+      hr = register_collection_notification_client(context);
+      if (FAILED(hr)) {
+        return CUBEB_ERROR;
+      }
+    }
+  }
+
+  return CUBEB_OK;
+}
+
+cubeb_ops const wasapi_ops = {
+    /*.init =*/wasapi_init,
+    /*.get_backend_id =*/wasapi_get_backend_id,
+    /*.get_max_channel_count =*/wasapi_get_max_channel_count,
+    /*.get_min_latency =*/wasapi_get_min_latency,
+    /*.get_preferred_sample_rate =*/wasapi_get_preferred_sample_rate,
+    /*.enumerate_devices =*/wasapi_enumerate_devices,
+    /*.device_collection_destroy =*/wasapi_device_collection_destroy,
+    /*.destroy =*/wasapi_destroy,
+    /*.stream_init =*/wasapi_stream_init,
+    /*.stream_destroy =*/wasapi_stream_destroy,
+    /*.stream_start =*/wasapi_stream_start,
+    /*.stream_stop =*/wasapi_stream_stop,
+    /*.stream_get_position =*/wasapi_stream_get_position,
+    /*.stream_get_latency =*/wasapi_stream_get_latency,
+    /*.stream_get_input_latency =*/wasapi_stream_get_input_latency,
+    /*.stream_set_volume =*/wasapi_stream_set_volume,
+    /*.stream_set_name =*/NULL,
+    /*.stream_get_current_device =*/NULL,
+    /*.stream_device_destroy =*/NULL,
+    /*.stream_register_device_changed_callback =*/NULL,
+    /*.register_device_collection_changed =*/
+    wasapi_register_device_collection_changed,
+};
+} // namespace