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diff --git a/dom/media/AudioInputSource.h b/dom/media/AudioInputSource.h
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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#ifndef DOM_MEDIA_AudioInputSource_H_
+#define DOM_MEDIA_AudioInputSource_H_
+
+#include "AudioDriftCorrection.h"
+#include "AudioSegment.h"
+#include "CubebInputStream.h"
+#include "CubebUtils.h"
+#include "mozilla/ProfilerUtils.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/SPSCQueue.h"
+#include "mozilla/SharedThreadPool.h"
+
+namespace mozilla {
+
+// This is an interface to operate an input-only audio stream within a
+// cubeb-task thread on a specific thread. Once the class instance is created,
+// all its operations must be called on the same thread.
+//
+// The audio data is periodically produced by the underlying audio stream on the
+// stream's callback thread, and can be safely read by GetAudioSegment() on a
+// specific thread.
+class AudioInputSource : public CubebInputStream::Listener {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(AudioInputSource, override);
+
+  using Id = uint32_t;
+
+  class EventListener {
+   public:
+    NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING;
+
+    // This two events will be fired on main thread.
+    virtual void AudioDeviceChanged(Id aId) = 0;
+    enum class State { Started, Stopped, Drained, Error };
+    virtual void AudioStateCallback(Id aId, State aState) = 0;
+
+   protected:
+    EventListener() = default;
+    virtual ~EventListener() = default;
+  };
+
+  AudioInputSource(RefPtr<EventListener>&& aListener, Id aSourceId,
+                   CubebUtils::AudioDeviceID aDeviceId, uint32_t aChannelCount,
+                   bool aIsVoice, const PrincipalHandle& aPrincipalHandle,
+                   TrackRate aSourceRate, TrackRate aTargetRate,
+                   uint32_t aBufferMs);
+
+  // The following functions should always be called in the same thread: They
+  // are always run on MediaTrackGraph's graph thread.
+  // Starts producing audio data.
+  void Start();
+  // Stops producing audio data.
+  void Stop();
+  // Returns the AudioSegment with aDuration of data inside.
+  // The graph thread can change behind the scene, e.g., cubeb stream reinit due
+  // to default output device changed). When this happens, we need to notify
+  // mSPSCQueue to change its data consumer.
+  enum class Consumer { Same, Changed };
+  AudioSegment GetAudioSegment(TrackTime aDuration, Consumer aConsumer);
+
+  // CubebInputStream::Listener interface: These are used only for the
+  // underlying audio stream. No user should call these APIs.
+  // This will be fired on audio callback thread.
+  long DataCallback(const void* aBuffer, long aFrames) override;
+  // This can be fired on any thread.
+  void StateCallback(cubeb_state aState) override;
+  // This can be fired on any thread.
+  void DeviceChangedCallback() override;
+
+  // Any threads:
+  // The unique id of this source.
+  const Id mId;
+  // The id of this audio device producing the data.
+  const CubebUtils::AudioDeviceID mDeviceId;
+  // The channel count of audio data produced.
+  const uint32_t mChannelCount;
+  // The sample rate of the audio data produced.
+  const TrackRate mRate;
+  // Indicate whether the audio stream is for voice or not.
+  const bool mIsVoice;
+  // The principal of the audio data produced.
+  const PrincipalHandle mPrincipalHandle;
+
+ protected:
+  ~AudioInputSource() = default;
+
+ private:
+  // Underlying audio thread only.
+  bool CheckThreadIdChanged();
+
+  // Any thread.
+  const bool mSandboxed;
+
+  // Thread id of the underlying audio thread. Underlying audio thread only.
+  std::atomic<ProfilerThreadId> mAudioThreadId;
+
+  // Forward the underlying event from main thread.
+  const RefPtr<EventListener> mEventListener;
+
+  // Shared thread pool containing only one thread for cubeb operations.
+  // The cubeb operations: Start() and Stop() will be called on
+  // MediaTrackGraph's graph thread, which can be the cubeb stream's callback
+  // thread. Running cubeb operations within cubeb stream callback thread can
+  // cause the deadlock on Linux, so we dispatch those operations to the task
+  // thread.
+  const RefPtr<SharedThreadPool> mTaskThread;
+
+  // Correct the drift between the underlying audio stream and its reader.
+  AudioDriftCorrection mDriftCorrector;
+
+  // An input-only cubeb stream operated within mTaskThread.
+  UniquePtr<CubebInputStream> mStream;
+
+  // A single-producer-single-consumer lock-free queue whose data is produced by
+  // the audio callback thread and consumed by AudioInputSource's data reader.
+  SPSCQueue<AudioChunk> mSPSCQueue{30};
+};
+
+}  // namespace mozilla
+
+#endif  // DOM_MEDIA_AudioInputSource_H_