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+/** @file
+ * PDM - Pluggable Device Manager, audio interfaces.
+ */
+
+/*
+ * Copyright (C) 2006-2019 Oracle Corporation
+ *
+ * This file is part of VirtualBox Open Source Edition (OSE), as
+ * available from http://www.virtualbox.org. This file is free software;
+ * you can redistribute it and/or modify it under the terms of the GNU
+ * General Public License (GPL) as published by the Free Software
+ * Foundation, in version 2 as it comes in the "COPYING" file of the
+ * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+ * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+ *
+ * The contents of this file may alternatively be used under the terms
+ * of the Common Development and Distribution License Version 1.0
+ * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+ * VirtualBox OSE distribution, in which case the provisions of the
+ * CDDL are applicable instead of those of the GPL.
+ *
+ * You may elect to license modified versions of this file under the
+ * terms and conditions of either the GPL or the CDDL or both.
+ */
+
+/**
+ * == Audio architecture overview
+ *
+ * The audio architecture mainly consists of two PDM interfaces, PDMAUDIOCONNECTOR
+ * and PDMIHOSTAUDIO.
+ *
+ * The PDMAUDIOCONNECTOR interface is responsible of connecting a device emulation, such
+ * as SB16, AC'97 and HDA to one or multiple audio backend(s). Its API abstracts audio
+ * stream handling and I/O functions, device enumeration and so on.
+ *
+ * The PDMIHOSTAUDIO interface must be implemented by all audio backends to provide an
+ * abstract and common way of accessing needed functions, such as transferring output audio
+ * data for playing audio or recording input from the host.
+ *
+ * A device emulation can have one or more LUNs attached to it, whereas these LUNs in turn
+ * then all have their own PDMIAUDIOCONNECTOR, making it possible to connect multiple backends
+ * to a certain device emulation stream (multiplexing).
+ *
+ * An audio backend's job is to record and/or play audio data (depending on its capabilities).
+ * It highly depends on the host it's running on and needs very specific (host-OS-dependent) code.
+ * The backend itself only has very limited ways of accessing and/or communicating with the
+ * PDMIAUDIOCONNECTOR interface via callbacks, but never directly with the device emulation or
+ * other parts of the audio sub system.
+ *
+ *
+ * == Mixing
+ *
+ * The AUDIOMIXER API is optionally available to create and manage virtual audio mixers.
+ * Such an audio mixer in turn then can be used by the device emulation code to manage all
+ * the multiplexing to/from the connected LUN audio streams.
+ *
+ * Currently only input and output stream are supported. Duplex stream are not supported yet.
+ *
+ * This also is handy if certain LUN audio streams should be added or removed during runtime.
+ *
+ * To create a group of either input or output streams the AUDMIXSINK API can be used.
+ *
+ * For example: The device emulation has one hardware output stream (HW0), and that output
+ * stream shall be available to all connected LUN backends. For that to happen,
+ * an AUDMIXSINK sink has to be created and attached to the device's AUDIOMIXER object.
+ *
+ * As every LUN has its own AUDMIXSTREAM object, adding all those objects to the
+ * just created audio mixer sink will do the job.
+ *
+ * Note: The AUDIOMIXER API is purely optional and is not used by all currently implemented
+ * device emulations (e.g. SB16).
+ *
+ *
+ * == Data processing
+ *
+ * Audio input / output data gets handed-off to/from the device emulation in an unmodified
+ * - that is, raw - way. The actual audio frame / sample conversion is done via the PDMAUDIOMIXBUF API.
+ *
+ * This concentrates the audio data processing in one place and makes it easier to test / benchmark
+ * such code.
+ *
+ * A PDMAUDIOFRAME is the internal representation of a single audio frame, which consists of a single left
+ * and right audio sample in time. Only mono (1) and stereo (2) channel(s) currently are supported.
+ *
+ *
+ * == Timing
+ *
+ * Handling audio data in a virtual environment is hard, as the human perception is very sensitive
+ * to the slightest cracks and stutters in the audible data. This can happen if the VM's timing is
+ * lagging behind or not within the expected time frame.
+ *
+ * The two main components which unfortunately contradict each other is a) the audio device emulation
+ * and b) the audio backend(s) on the host. Those need to be served in a timely manner to function correctly.
+ * To make e.g. the device emulation rely on the pace the host backend(s) set - or vice versa - will not work,
+ * as the guest's audio system / drivers then will not be able to compensate this accordingly.
+ *
+ * So each component, the device emulation, the audio connector(s) and the backend(s) must do its thing
+ * *when* it needs to do it, independently of the others. For that we use various (small) ring buffers to
+ * (hopefully) serve all components with the amount of data *when* they need it.
+ *
+ * Additionally, the device emulation can run with a different audio frame size, while the backends(s) may
+ * require a different frame size (16 bit stereo -> 8 bit mono, for example).
+ *
+ * The device emulation can give the audio connector(s) a scheduling hint (optional), e.g. in which interval
+ * it expects any data processing.
+ *
+ * A data transfer for playing audio data from the guest on the host looks like this:
+ * (RB = Ring Buffer, MB = Mixing Buffer)
+ *
+ * (A) Device DMA -> (B) Device RB -> (C) Audio Connector Guest MB -> (D) Audio Connector Host MB -> \
+ * (E) Backend RB (optional, up to the backend) > (F) Backend audio framework
+ *
+ * For capturing audio data the above chain is similar, just in a different direction, of course.
+ *
+ * The audio connector hereby plays a key role when it comes to (pre-) buffering data to minimize any audio stutters
+ * and/or cracks. The following values, which also can be tweaked via CFGM / extra-data are available:
+ *
+ * - The pre-buffering time (in ms): Audio data which needs to be buffered before any playback (or capturing) can happen.
+ * - The actual buffer size (in ms): How big the mixing buffer (for C and D) will be.
+ * - The period size (in ms): How big a chunk of audio (often called period or fragment) for F must be to get handled correctly.
+ *
+ * The above values can be set on a per-driver level, whereas input and output streams for a driver also can be handled
+ * set independently. The verbose audio (release) log will tell about the (final) state of each audio stream.
+ *
+ *
+ * == Diagram
+ *
+ * +-------------------------+
+ * +-------------------------+ +-------------------------+ +-------------------+
+ * |PDMAUDIOSTREAM | |PDMAUDIOCONNECTOR | + ++|LUN |
+ * |-------------------------| |-------------------------| | |||-------------------|
+ * |PDMAUDIOMIXBUF |+------>|PDMAUDIOSTREAM Host |+---|-|||PDMIAUDIOCONNECTOR |
+ * |PDMAUDIOSTREAMCFG |+------>|PDMAUDIOSTREAM Guest | | |||AUDMIXSTREAM |
+ * | | |Device capabilities | | ||| |
+ * | | |Device configuration | | ||| |
+ * | | | | | ||| |
+ * | | +|PDMIHOSTAUDIO | | ||| |
+ * | | ||+-----------------------+| | ||+-------------------+
+ * +-------------------------+ |||Backend storage space || | ||
+ * ||+-----------------------+| | ||
+ * |+-------------------------+ | ||
+ * | | ||
+ * +---------------------+ | | ||
+ * |PDMIHOSTAUDIO | | | ||
+ * |+--------------+ | | +-------------------+ | || +-------------+
+ * ||DirectSound | | | |AUDMIXSINK | | || |AUDIOMIXER |
+ * |+--------------+ | | |-------------------| | || |-------------|
+ * | | | |AUDMIXSTREAM0 |+---|-||----->|AUDMIXSINK0 |
+ * |+--------------+ | | |AUDMIXSTREAM1 |+---|-||----->|AUDMIXSINK1 |
+ * ||PulseAudio | | | |AUDMIXSTREAMn |+---|-||----->|AUDMIXSINKn |
+ * |+--------------+ |+----------+ +-------------------+ | || +-------------+
+ * | | | ||
+ * |+--------------+ | | ||
+ * ||Core Audio | | | ||
+ * |+--------------+ | | ||
+ * | | | ||
+ * | | | ||+----------------------------------+
+ * | | | |||Device (SB16 / AC'97 / HDA) |
+ * | | | |||----------------------------------|
+ * +---------------------+ | |||AUDIOMIXER (Optional) |
+ * | |||AUDMIXSINK0 (Optional) |
+ * | |||AUDMIXSINK1 (Optional) |
+ * | |||AUDMIXSINKn (Optional) |
+ * | ||| |
+ * | |+|LUN0 |
+ * | ++|LUN1 |
+ * +--+|LUNn |
+ * | |
+ * | |
+ * | |
+ * +----------------------------------+
+ */
+
+#ifndef VBOX_INCLUDED_vmm_pdmaudioifs_h
+#define VBOX_INCLUDED_vmm_pdmaudioifs_h
+#ifndef RT_WITHOUT_PRAGMA_ONCE
+# pragma once
+#endif
+
+#include <iprt/assertcompile.h>
+#include <iprt/circbuf.h>
+#include <iprt/list.h>
+#include <iprt/path.h>
+
+#include <VBox/types.h>
+#ifdef VBOX_WITH_STATISTICS
+# include <VBox/vmm/stam.h>
+#endif
+
+/** @defgroup grp_pdm_ifs_audio PDM Audio Interfaces
+ * @ingroup grp_pdm_interfaces
+ * @{
+ */
+
+#ifndef VBOX_AUDIO_DEBUG_DUMP_PCM_DATA_PATH
+# ifdef RT_OS_WINDOWS
+# define VBOX_AUDIO_DEBUG_DUMP_PCM_DATA_PATH "c:\\temp\\"
+# else
+# define VBOX_AUDIO_DEBUG_DUMP_PCM_DATA_PATH "/tmp/"
+# endif
+#endif
+
+/** PDM audio driver instance flags. */
+typedef uint32_t PDMAUDIODRVFLAGS;
+
+/** No flags set. */
+#define PDMAUDIODRVFLAGS_NONE 0
+/** Marks a primary audio driver which is critical
+ * when running the VM. */
+#define PDMAUDIODRVFLAGS_PRIMARY RT_BIT(0)
+
+/**
+ * Audio format in signed or unsigned variants.
+ */
+typedef enum PDMAUDIOFMT
+{
+ /** Invalid format, do not use. */
+ PDMAUDIOFMT_INVALID,
+ /** 8-bit, unsigned. */
+ PDMAUDIOFMT_U8,
+ /** 8-bit, signed. */
+ PDMAUDIOFMT_S8,
+ /** 16-bit, unsigned. */
+ PDMAUDIOFMT_U16,
+ /** 16-bit, signed. */
+ PDMAUDIOFMT_S16,
+ /** 32-bit, unsigned. */
+ PDMAUDIOFMT_U32,
+ /** 32-bit, signed. */
+ PDMAUDIOFMT_S32,
+ /** Hack to blow the type up to 32-bit. */
+ PDMAUDIOFMT_32BIT_HACK = 0x7fffffff
+} PDMAUDIOFMT;
+
+/**
+ * Audio direction.
+ */
+typedef enum PDMAUDIODIR
+{
+ /** Unknown direction. */
+ PDMAUDIODIR_UNKNOWN = 0,
+ /** Input. */
+ PDMAUDIODIR_IN = 1,
+ /** Output. */
+ PDMAUDIODIR_OUT = 2,
+ /** Duplex handling. */
+ PDMAUDIODIR_ANY = 3,
+ /** Hack to blow the type up to 32-bit. */
+ PDMAUDIODIR_32BIT_HACK = 0x7fffffff
+} PDMAUDIODIR;
+
+/** Device latency spec in milliseconds (ms). */
+typedef uint32_t PDMAUDIODEVLATSPECMS;
+
+/** Device latency spec in seconds (s). */
+typedef uint32_t PDMAUDIODEVLATSPECSEC;
+
+/** Audio device flags. Use with PDMAUDIODEV_FLAG_ flags. */
+typedef uint32_t PDMAUDIODEVFLAG;
+
+/** No flags set. */
+#define PDMAUDIODEV_FLAGS_NONE 0
+/** The device marks the default device within the host OS. */
+#define PDMAUDIODEV_FLAGS_DEFAULT RT_BIT(0)
+/** The device can be removed at any time and we have to deal with it. */
+#define PDMAUDIODEV_FLAGS_HOTPLUG RT_BIT(1)
+/** The device is known to be buggy and needs special treatment. */
+#define PDMAUDIODEV_FLAGS_BUGGY RT_BIT(2)
+/** Ignore the device, no matter what. */
+#define PDMAUDIODEV_FLAGS_IGNORE RT_BIT(3)
+/** The device is present but marked as locked by some other application. */
+#define PDMAUDIODEV_FLAGS_LOCKED RT_BIT(4)
+/** The device is present but not in an alive state (dead). */
+#define PDMAUDIODEV_FLAGS_DEAD RT_BIT(5)
+
+/**
+ * Audio device type.
+ */
+typedef enum PDMAUDIODEVICETYPE
+{
+ /** Unknown device type. This is the default. */
+ PDMAUDIODEVICETYPE_UNKNOWN = 0,
+ /** Dummy device; for backends which are not able to report
+ * actual device information (yet). */
+ PDMAUDIODEVICETYPE_DUMMY,
+ /** The device is built into the host (non-removable). */
+ PDMAUDIODEVICETYPE_BUILTIN,
+ /** The device is an (external) USB device. */
+ PDMAUDIODEVICETYPE_USB,
+ /** Hack to blow the type up to 32-bit. */
+ PDMAUDIODEVICETYPE_32BIT_HACK = 0x7fffffff
+} PDMAUDIODEVICETYPE;
+
+/**
+ * Audio device instance data.
+ */
+typedef struct PDMAUDIODEVICE
+{
+ /** List node. */
+ RTLISTNODE Node;
+ /** Friendly name of the device, if any. */
+ char szName[64];
+ /** The device type. */
+ PDMAUDIODEVICETYPE enmType;
+ /** Reference count indicating how many audio streams currently are relying on this device. */
+ uint8_t cRefCount;
+ /** Usage of the device. */
+ PDMAUDIODIR enmUsage;
+ /** Device flags. */
+ PDMAUDIODEVFLAG fFlags;
+ /** Maximum number of input audio channels the device supports. */
+ uint8_t cMaxInputChannels;
+ /** Maximum number of output audio channels the device supports. */
+ uint8_t cMaxOutputChannels;
+ /** Additional data which might be relevant for the current context. */
+ void *pvData;
+ /** Size of the additional data. */
+ size_t cbData;
+ /** Device type union, based on enmType. */
+ union
+ {
+ /** USB type specifics. */
+ struct
+ {
+ /** Vendor ID. */
+ int16_t VID;
+ /** Product ID. */
+ int16_t PID;
+ } USB;
+ } Type;
+} PDMAUDIODEVICE, *PPDMAUDIODEVICE;
+
+/**
+ * Structure for keeping an audio device enumeration.
+ */
+typedef struct PDMAUDIODEVICEENUM
+{
+ /** Number of audio devices in the list. */
+ uint16_t cDevices;
+ /** List of audio devices. */
+ RTLISTANCHOR lstDevices;
+} PDMAUDIODEVICEENUM, *PPDMAUDIODEVICEENUM;
+
+/**
+ * Audio (static) configuration of an audio host backend.
+ */
+typedef struct PDMAUDIOBACKENDCFG
+{
+ /** The backend's friendly name. */
+ char szName[32];
+ /** Size (in bytes) of the host backend's audio output stream structure. */
+ size_t cbStreamOut;
+ /** Size (in bytes) of the host backend's audio input stream structure. */
+ size_t cbStreamIn;
+ /** Number of concurrent output (playback) streams supported on the host.
+ * UINT32_MAX for unlimited concurrent streams, 0 if no concurrent input streams are supported. */
+ uint32_t cMaxStreamsOut;
+ /** Number of concurrent input (recording) streams supported on the host.
+ * UINT32_MAX for unlimited concurrent streams, 0 if no concurrent input streams are supported. */
+ uint32_t cMaxStreamsIn;
+} PDMAUDIOBACKENDCFG, *PPDMAUDIOBACKENDCFG;
+
+/**
+ * A single audio frame.
+ *
+ * Currently only two (2) channels, left and right, are supported.
+ *
+ * Note: When changing this structure, make sure to also handle
+ * VRDP's input / output processing in DrvAudioVRDE, as VRDP
+ * expects audio data in st_sample_t format (historical reasons)
+ * which happens to be the same as PDMAUDIOFRAME for now.
+ */
+typedef struct PDMAUDIOFRAME
+{
+ /** Left channel. */
+ int64_t i64LSample;
+ /** Right channel. */
+ int64_t i64RSample;
+} PDMAUDIOFRAME;
+/** Pointer to a single (stereo) audio frame. */
+typedef PDMAUDIOFRAME *PPDMAUDIOFRAME;
+/** Pointer to a const single (stereo) audio frame. */
+typedef PDMAUDIOFRAME const *PCPDMAUDIOFRAME;
+
+typedef enum PDMAUDIOENDIANNESS
+{
+ /** The usual invalid endian. */
+ PDMAUDIOENDIANNESS_INVALID,
+ /** Little endian. */
+ PDMAUDIOENDIANNESS_LITTLE,
+ /** Bit endian. */
+ PDMAUDIOENDIANNESS_BIG,
+ /** Endianness doesn't have a meaning in the context. */
+ PDMAUDIOENDIANNESS_NA,
+ /** The end of the valid endian values (exclusive). */
+ PDMAUDIOENDIANNESS_END,
+ /** Hack to blow the type up to 32-bit. */
+ PDMAUDIOENDIANNESS_32BIT_HACK = 0x7fffffff
+} PDMAUDIOENDIANNESS;
+
+/**
+ * Audio playback destinations.
+ */
+typedef enum PDMAUDIOPLAYBACKDEST
+{
+ /** Unknown destination. */
+ PDMAUDIOPLAYBACKDEST_UNKNOWN = 0,
+ /** Front channel. */
+ PDMAUDIOPLAYBACKDEST_FRONT,
+ /** Center / LFE (Subwoofer) channel. */
+ PDMAUDIOPLAYBACKDEST_CENTER_LFE,
+ /** Rear channel. */
+ PDMAUDIOPLAYBACKDEST_REAR,
+ /** Hack to blow the type up to 32-bit. */
+ PDMAUDIOPLAYBACKDEST_32BIT_HACK = 0x7fffffff
+} PDMAUDIOPLAYBACKDEST;
+
+/**
+ * Audio recording sources.
+ */
+typedef enum PDMAUDIORECSOURCE
+{
+ /** Unknown recording source. */
+ PDMAUDIORECSOURCE_UNKNOWN = 0,
+ /** Microphone-In. */
+ PDMAUDIORECSOURCE_MIC,
+ /** CD. */
+ PDMAUDIORECSOURCE_CD,
+ /** Video-In. */
+ PDMAUDIORECSOURCE_VIDEO,
+ /** AUX. */
+ PDMAUDIORECSOURCE_AUX,
+ /** Line-In. */
+ PDMAUDIORECSOURCE_LINE,
+ /** Phone-In. */
+ PDMAUDIORECSOURCE_PHONE,
+ /** Hack to blow the type up to 32-bit. */
+ PDMAUDIORECSOURCE_32BIT_HACK = 0x7fffffff
+} PDMAUDIORECSOURCE;
+
+/**
+ * Audio stream (data) layout.
+ */
+typedef enum PDMAUDIOSTREAMLAYOUT
+{
+ /** Unknown access type; do not use. */
+ PDMAUDIOSTREAMLAYOUT_UNKNOWN = 0,
+ /** Non-interleaved access, that is, consecutive
+ * access to the data. */
+ PDMAUDIOSTREAMLAYOUT_NON_INTERLEAVED,
+ /** Interleaved access, where the data can be
+ * mixed together with data of other audio streams. */
+ PDMAUDIOSTREAMLAYOUT_INTERLEAVED,
+ /** Complex layout, which does not fit into the
+ * interleaved / non-interleaved layouts. */
+ PDMAUDIOSTREAMLAYOUT_COMPLEX,
+ /** Raw (pass through) data, with no data layout processing done.
+ *
+ * This means that this stream will operate on PDMAUDIOFRAME data
+ * directly. Don't use this if you don't have to. */
+ PDMAUDIOSTREAMLAYOUT_RAW,
+ /** Hack to blow the type up to 32-bit. */
+ PDMAUDIOSTREAMLAYOUT_32BIT_HACK = 0x7fffffff
+} PDMAUDIOSTREAMLAYOUT, *PPDMAUDIOSTREAMLAYOUT;
+
+/** No stream channel data flags defined. */
+#define PDMAUDIOSTREAMCHANNELDATA_FLAG_NONE 0
+
+/**
+ * Structure for keeping a stream channel data block around.
+ */
+typedef struct PDMAUDIOSTREAMCHANNELDATA
+{
+ /** Circular buffer for the channel data. */
+ PRTCIRCBUF pCircBuf;
+ /** Amount of audio data (in bytes) acquired for reading. */
+ size_t cbAcq;
+ /** Channel data flags. */
+ uint32_t fFlags;
+} PDMAUDIOSTREAMCHANNELDATA, *PPDMAUDIOSTREAMCHANNELDATA;
+
+/**
+ * Enumeration for standard speaker channel IDs.
+ * This can cover up to 11.0 surround sound.
+ *
+ * Note: Any of those channels can be marked / used as the LFE channel (played through the subwoofer).
+ */
+typedef enum PDMAUDIOSTREAMCHANNELID
+{
+ /** Unknown / not set channel ID. */
+ PDMAUDIOSTREAMCHANNELID_UNKNOWN = 0,
+ /** Front left channel. */
+ PDMAUDIOSTREAMCHANNELID_FRONT_LEFT,
+ /** Front right channel. */
+ PDMAUDIOSTREAMCHANNELID_FRONT_RIGHT,
+ /** Front center channel. */
+ PDMAUDIOSTREAMCHANNELID_FRONT_CENTER,
+ /** Low frequency effects (subwoofer) channel. */
+ PDMAUDIOSTREAMCHANNELID_LFE,
+ /** Rear left channel. */
+ PDMAUDIOSTREAMCHANNELID_REAR_LEFT,
+ /** Rear right channel. */
+ PDMAUDIOSTREAMCHANNELID_REAR_RIGHT,
+ /** Front left of center channel. */
+ PDMAUDIOSTREAMCHANNELID_FRONT_LEFT_OF_CENTER,
+ /** Front right of center channel. */
+ PDMAUDIOSTREAMCHANNELID_FRONT_RIGHT_OF_CENTER,
+ /** Rear center channel. */
+ PDMAUDIOSTREAMCHANNELID_REAR_CENTER,
+ /** Side left channel. */
+ PDMAUDIOSTREAMCHANNELID_SIDE_LEFT,
+ /** Side right channel. */
+ PDMAUDIOSTREAMCHANNELID_SIDE_RIGHT,
+ /** Left height channel. */
+ PDMAUDIOSTREAMCHANNELID_LEFT_HEIGHT,
+ /** Right height channel. */
+ PDMAUDIOSTREAMCHANNELID_RIGHT_HEIGHT,
+ /** Hack to blow the type up to 32-bit. */
+ PDMAUDIOSTREAMCHANNELID_32BIT_HACK = 0x7fffffff
+} PDMAUDIOSTREAMCHANNELID;
+
+/**
+ * Structure for mapping a single (mono) channel or dual (stereo) channels of an audio stream (aka stream profile).
+ *
+ * An audio stream consists of one or multiple channels (e.g. 1 for mono, 2 for stereo),
+ * depending on the configuration.
+ */
+typedef struct PDMAUDIOSTREAMMAP
+{
+ /** Array of channel IDs being handled.
+ * Note: The first (zero-based) index specifies the leftmost channel. */
+ PDMAUDIOSTREAMCHANNELID aID[2];
+ /** Step size (in bytes) to the channel's next frame. */
+ size_t cbSize;
+ /** Frame size (in bytes) of this channel. */
+ size_t cbFrame;
+ /** Offset (in bytes) to first frame in the data block. */
+ size_t cbFirst;
+ /** Offset (in bytes) to the next frame in the data block. */
+ size_t cbOff;
+ /** Associated data buffer. */
+ PDMAUDIOSTREAMCHANNELDATA Data;
+} PDMAUDIOSTREAMMAP, *PPDMAUDIOSTREAMMAP;
+
+/**
+ * Union for keeping an audio stream destination or source.
+ */
+typedef union PDMAUDIODESTSOURCE
+{
+ /** Desired playback destination (for an output stream). */
+ PDMAUDIOPLAYBACKDEST Dest;
+ /** Desired recording source (for an input stream). */
+ PDMAUDIORECSOURCE Source;
+} PDMAUDIODESTSOURCE, *PPDMAUDIODESTSOURCE;
+
+/**
+ * Properties of audio streams for host/guest for in or out directions.
+ */
+typedef struct PDMAUDIOPCMPROPS
+{
+ /** Sample width (in bytes). */
+ uint8_t cBytes;
+ /** Number of audio channels. */
+ uint8_t cChannels;
+ /** Shift count used for faster calculation of various
+ * values, such as the alignment, bytes to frames and so on.
+ * Depends on number of stream channels and the stream format
+ * being used.
+ *
+ ** @todo Use some RTAsmXXX functions instead?
+ */
+ uint8_t cShift;
+ /** Signed or unsigned sample. */
+ bool fSigned : 1;
+ /** Whether the endianness is swapped or not. */
+ bool fSwapEndian : 1;
+ /** Sample frequency in Hertz (Hz). */
+ uint32_t uHz;
+} PDMAUDIOPCMPROPS;
+AssertCompileSizeAlignment(PDMAUDIOPCMPROPS, 8);
+/** Pointer to audio stream properties. */
+typedef PDMAUDIOPCMPROPS *PPDMAUDIOPCMPROPS;
+
+/** Initializor for PDMAUDIOPCMPROPS. */
+#define PDMAUDIOPCMPROPS_INITIALIZOR(a_cBytes, a_fSigned, a_cCannels, a_uHz, a_cShift, a_fSwapEndian) \
+ { a_cBytes, a_cCannels, a_cShift, a_fSigned, a_fSwapEndian, a_uHz }
+/** Calculates the cShift value of given sample bits and audio channels.
+ * Note: Does only support mono/stereo channels for now. */
+#define PDMAUDIOPCMPROPS_MAKE_SHIFT_PARMS(cBytes, cChannels) ((cChannels == 2) + (cBytes / 2))
+/** Calculates the cShift value of a PDMAUDIOPCMPROPS structure. */
+#define PDMAUDIOPCMPROPS_MAKE_SHIFT(pProps) PDMAUDIOPCMPROPS_MAKE_SHIFT_PARMS((pProps)->cBytes, (pProps)->cChannels)
+/** Converts (audio) frames to bytes.
+ * Needs the cShift value set correctly, using PDMAUDIOPCMPROPS_MAKE_SHIFT. */
+#define PDMAUDIOPCMPROPS_F2B(pProps, frames) ((frames) << (pProps)->cShift)
+/** Converts bytes to (audio) frames.
+ * Needs the cShift value set correctly, using PDMAUDIOPCMPROPS_MAKE_SHIFT. */
+#define PDMAUDIOPCMPROPS_B2F(pProps, cb) (cb >> (pProps)->cShift)
+
+/**
+ * Structure for keeping an audio stream configuration.
+ */
+typedef struct PDMAUDIOSTREAMCFG
+{
+ /** Friendly name of the stream. */
+ char szName[64];
+ /** Direction of the stream. */
+ PDMAUDIODIR enmDir;
+ /** Destination / source indicator, depending on enmDir. */
+ PDMAUDIODESTSOURCE DestSource;
+ /** The stream's PCM properties. */
+ PDMAUDIOPCMPROPS Props;
+ /** The stream's audio data layout.
+ * This indicates how the audio data buffers to/from the backend is being layouted.
+ *
+ * Currently, the following layouts are supported by the audio connector:
+ *
+ * PDMAUDIOSTREAMLAYOUT_NON_INTERLEAVED:
+ * One stream at once. The consecutive audio data is exactly in the format and frame width
+ * like defined in the PCM properties. This is the default.
+ *
+ * PDMAUDIOSTREAMLAYOUT_RAW:
+ * Can be one or many streams at once, depending on the stream's mixing buffer setup.
+ * The audio data will get handled as PDMAUDIOFRAME frames without any modification done. */
+ PDMAUDIOSTREAMLAYOUT enmLayout;
+ /** Device emulation-specific data needed for the audio connector. */
+ struct
+ {
+ /** Scheduling hint set by the device emulation about when this stream is being served on average (in ms).
+ * Can be 0 if not hint given or some other mechanism (e.g. callbacks) is being used. */
+ uint32_t uSchedulingHintMs;
+ } Device;
+ /**
+ * Backend-specific data for the stream.
+ * On input (requested configuration) those values are set by the audio connector to let the backend know what we expect.
+ * On output (acquired configuration) those values reflect the values set and used by the backend.
+ * Set by the backend on return. Not all backends support all values / features.
+ */
+ struct
+ {
+ /** Period size of the stream (in audio frames).
+ * This value reflects the number of audio frames in between each hardware interrupt on the
+ * backend (host) side. 0 if not set / available by the backend. */
+ uint32_t cfPeriod;
+ /** (Ring) buffer size (in audio frames). Often is a multiple of cfPeriod.
+ * 0 if not set / available by the backend. */
+ uint32_t cfBufferSize;
+ /** Pre-buffering size (in audio frames). Frames needed in buffer before the stream becomes active (pre buffering).
+ * The bigger this value is, the more latency for the stream will occur.
+ * 0 if not set / available by the backend. UINT32_MAX if not defined (yet). */
+ uint32_t cfPreBuf;
+ } Backend;
+} PDMAUDIOSTREAMCFG;
+AssertCompileSizeAlignment(PDMAUDIOPCMPROPS, 8);
+/** Pointer to audio stream configuration keeper. */
+typedef PDMAUDIOSTREAMCFG *PPDMAUDIOSTREAMCFG;
+
+
+/** Converts (audio) frames to bytes. */
+#define PDMAUDIOSTREAMCFG_F2B(pCfg, frames) ((frames) << (pCfg->Props).cShift)
+/** Converts bytes to (audio) frames. */
+#define PDMAUDIOSTREAMCFG_B2F(pCfg, cb) (cb >> (pCfg->Props).cShift)
+
+#if defined(RT_LITTLE_ENDIAN)
+# define PDMAUDIOHOSTENDIANNESS PDMAUDIOENDIANNESS_LITTLE
+#elif defined(RT_BIG_ENDIAN)
+# define PDMAUDIOHOSTENDIANNESS PDMAUDIOENDIANNESS_BIG
+#else
+# error "Port me!"
+#endif
+
+/**
+ * Audio mixer controls.
+ */
+typedef enum PDMAUDIOMIXERCTL
+{
+ /** Unknown mixer control. */
+ PDMAUDIOMIXERCTL_UNKNOWN = 0,
+ /** Master volume. */
+ PDMAUDIOMIXERCTL_VOLUME_MASTER,
+ /** Front. */
+ PDMAUDIOMIXERCTL_FRONT,
+ /** Center / LFE (Subwoofer). */
+ PDMAUDIOMIXERCTL_CENTER_LFE,
+ /** Rear. */
+ PDMAUDIOMIXERCTL_REAR,
+ /** Line-In. */
+ PDMAUDIOMIXERCTL_LINE_IN,
+ /** Microphone-In. */
+ PDMAUDIOMIXERCTL_MIC_IN,
+ /** Hack to blow the type up to 32-bit. */
+ PDMAUDIOMIXERCTL_32BIT_HACK = 0x7fffffff
+} PDMAUDIOMIXERCTL;
+
+/**
+ * Audio stream commands. Used in the audio connector
+ * as well as in the actual host backends.
+ */
+typedef enum PDMAUDIOSTREAMCMD
+{
+ /** Unknown command, do not use. */
+ PDMAUDIOSTREAMCMD_UNKNOWN = 0,
+ /** Enables the stream. */
+ PDMAUDIOSTREAMCMD_ENABLE,
+ /** Disables the stream.
+ * For output streams this stops the stream after playing the remaining (buffered) audio data.
+ * For input streams this will deliver the remaining (captured) audio data and not accepting
+ * any new audio input data afterwards. */
+ PDMAUDIOSTREAMCMD_DISABLE,
+ /** Pauses the stream. */
+ PDMAUDIOSTREAMCMD_PAUSE,
+ /** Resumes the stream. */
+ PDMAUDIOSTREAMCMD_RESUME,
+ /** Tells the stream to drain itself.
+ * For output streams this plays all remaining (buffered) audio frames,
+ * for input streams this permits receiving any new audio frames.
+ * No supported by all backends. */
+ PDMAUDIOSTREAMCMD_DRAIN,
+ /** Tells the stream to drop all (buffered) audio data immediately.
+ * No supported by all backends. */
+ PDMAUDIOSTREAMCMD_DROP,
+ /** Hack to blow the type up to 32-bit. */
+ PDMAUDIOSTREAMCMD_32BIT_HACK = 0x7fffffff
+} PDMAUDIOSTREAMCMD;
+
+/**
+ * Audio volume parameters.
+ */
+typedef struct PDMAUDIOVOLUME
+{
+ /** Set to @c true if this stream is muted, @c false if not. */
+ bool fMuted;
+ /** Left channel volume.
+ * Range is from [0 ... 255], whereas 0 specifies
+ * the most silent and 255 the loudest value. */
+ uint8_t uLeft;
+ /** Right channel volume.
+ * Range is from [0 ... 255], whereas 0 specifies
+ * the most silent and 255 the loudest value. */
+ uint8_t uRight;
+} PDMAUDIOVOLUME, *PPDMAUDIOVOLUME;
+
+/** Defines the minimum volume allowed. */
+#define PDMAUDIO_VOLUME_MIN (0)
+/** Defines the maximum volume allowed. */
+#define PDMAUDIO_VOLUME_MAX (255)
+
+/**
+ * Structure for holding rate processing information
+ * of a source + destination audio stream. This is needed
+ * because both streams can differ regarding their rates
+ * and therefore need to be treated accordingly.
+ */
+typedef struct PDMAUDIOSTREAMRATE
+{
+ /** Current (absolute) offset in the output
+ * (destination) stream. */
+ uint64_t dstOffset;
+ /** Increment for moving dstOffset for the
+ * destination stream. This is needed because the
+ * source <-> destination rate might be different. */
+ uint64_t dstInc;
+ /** Current (absolute) offset in the input
+ * stream. */
+ uint32_t srcOffset;
+ /** Last processed frame of the input stream.
+ * Needed for interpolation. */
+ PDMAUDIOFRAME srcFrameLast;
+} PDMAUDIOSTREAMRATE, *PPDMAUDIOSTREAMRATE;
+
+/**
+ * Structure for holding mixing buffer volume parameters.
+ * The volume values are in fixed point style and must
+ * be converted to/from before using with e.g. PDMAUDIOVOLUME.
+ */
+typedef struct PDMAUDMIXBUFVOL
+{
+ /** Set to @c true if this stream is muted, @c false if not. */
+ bool fMuted;
+ /** Left volume to apply during conversion. Pass 0
+ * to convert the original values. May not apply to
+ * all conversion functions. */
+ uint32_t uLeft;
+ /** Right volume to apply during conversion. Pass 0
+ * to convert the original values. May not apply to
+ * all conversion functions. */
+ uint32_t uRight;
+} PDMAUDMIXBUFVOL, *PPDMAUDMIXBUFVOL;
+
+/**
+ * Structure for holding frame conversion parameters for
+ * the audioMixBufConvFromXXX / audioMixBufConvToXXX macros.
+ */
+typedef struct PDMAUDMIXBUFCONVOPTS
+{
+ /** Number of audio frames to convert. */
+ uint32_t cFrames;
+ union
+ {
+ struct
+ {
+ /** Volume to use for conversion. */
+ PDMAUDMIXBUFVOL Volume;
+ } From;
+ } RT_UNION_NM(u);
+} PDMAUDMIXBUFCONVOPTS;
+/** Pointer to conversion parameters for the audio mixer. */
+typedef PDMAUDMIXBUFCONVOPTS *PPDMAUDMIXBUFCONVOPTS;
+/** Pointer to const conversion parameters for the audio mixer. */
+typedef PDMAUDMIXBUFCONVOPTS const *PCPDMAUDMIXBUFCONVOPTS;
+
+/**
+ * Note: All internal handling is done in audio frames,
+ * not in bytes!
+ */
+typedef uint32_t PDMAUDIOMIXBUFFMT;
+typedef PDMAUDIOMIXBUFFMT *PPDMAUDIOMIXBUFFMT;
+
+/**
+ * Convertion-from function used by the PDM audio buffer mixer.
+ *
+ * @returns Number of audio frames returned.
+ * @param paDst Where to return the converted frames.
+ * @param pvSrc The source frame bytes.
+ * @param cbSrc Number of bytes to convert.
+ * @param pOpts Conversion options.
+ */
+typedef DECLCALLBACK(uint32_t) FNPDMAUDIOMIXBUFCONVFROM(PPDMAUDIOFRAME paDst, const void *pvSrc, uint32_t cbSrc,
+ PCPDMAUDMIXBUFCONVOPTS pOpts);
+/** Pointer to a convertion-from function used by the PDM audio buffer mixer. */
+typedef FNPDMAUDIOMIXBUFCONVFROM *PFNPDMAUDIOMIXBUFCONVFROM;
+
+/**
+ * Convertion-to function used by the PDM audio buffer mixer.
+ *
+ * @param pvDst Output buffer.
+ * @param paSrc The input frames.
+ * @param pOpts Conversion options.
+ */
+typedef DECLCALLBACK(void) FNPDMAUDIOMIXBUFCONVTO(void *pvDst, PCPDMAUDIOFRAME paSrc, PCPDMAUDMIXBUFCONVOPTS pOpts);
+/** Pointer to a convertion-to function used by the PDM audio buffer mixer. */
+typedef FNPDMAUDIOMIXBUFCONVTO *PFNPDMAUDIOMIXBUFCONVTO;
+
+typedef struct PDMAUDIOMIXBUF *PPDMAUDIOMIXBUF;
+typedef struct PDMAUDIOMIXBUF
+{
+ RTLISTNODE Node;
+ /** Name of the buffer. */
+ char *pszName;
+ /** Frame buffer. */
+ PPDMAUDIOFRAME pFrames;
+ /** Size of the frame buffer (in audio frames). */
+ uint32_t cFrames;
+ /** The current read position (in frames). */
+ uint32_t offRead;
+ /** The current write position (in frames). */
+ uint32_t offWrite;
+ /**
+ * Total frames already mixed down to the parent buffer (if any). Always starting at
+ * the parent's offRead position.
+ *
+ * Note: Count always is specified in parent frames, as the sample count can differ between parent
+ * and child.
+ */
+ uint32_t cMixed;
+ /** How much audio frames are currently being used
+ * in this buffer.
+ * Note: This also is known as the distance in ring buffer terms. */
+ uint32_t cUsed;
+ /** Pointer to parent buffer (if any). */
+ PPDMAUDIOMIXBUF pParent;
+ /** List of children mix buffers to keep in sync with (if being a parent buffer). */
+ RTLISTANCHOR lstChildren;
+ /** Number of children mix buffers kept in lstChildren. */
+ uint32_t cChildren;
+ /** Intermediate structure for buffer conversion tasks. */
+ PPDMAUDIOSTREAMRATE pRate;
+ /** Internal representation of current volume used for mixing. */
+ PDMAUDMIXBUFVOL Volume;
+ /** This buffer's audio format. */
+ PDMAUDIOMIXBUFFMT AudioFmt;
+ /** Standard conversion-to function for set AudioFmt. */
+ PFNPDMAUDIOMIXBUFCONVTO pfnConvTo;
+ /** Standard conversion-from function for set AudioFmt. */
+ PFNPDMAUDIOMIXBUFCONVFROM pfnConvFrom;
+ /**
+ * Ratio of the associated parent stream's frequency by this stream's
+ * frequency (1<<32), represented as a signed 64 bit integer.
+ *
+ * For example, if the parent stream has a frequency of 44 khZ, and this
+ * stream has a frequency of 11 kHz, the ration then would be
+ * (44/11 * (1 << 32)).
+ *
+ * Currently this does not get changed once assigned.
+ */
+ int64_t iFreqRatio;
+ /** For quickly converting frames <-> bytes and vice versa. */
+ uint8_t cShift;
+} PDMAUDIOMIXBUF;
+
+typedef uint32_t PDMAUDIOFILEFLAGS;
+
+/** No flags defined. */
+#define PDMAUDIOFILE_FLAG_NONE 0
+/** Keep the audio file even if it contains no audio data. */
+#define PDMAUDIOFILE_FLAG_KEEP_IF_EMPTY RT_BIT(0)
+/** Audio file flag validation mask. */
+#define PDMAUDIOFILE_FLAG_VALID_MASK 0x1
+
+/** Audio file default open flags. */
+#define PDMAUDIOFILE_DEFAULT_OPEN_FLAGS (RTFILE_O_OPEN_CREATE | RTFILE_O_APPEND | RTFILE_O_WRITE | RTFILE_O_DENY_WRITE)
+
+/**
+ * Audio file types.
+ */
+typedef enum PDMAUDIOFILETYPE
+{
+ /** Unknown type, do not use. */
+ PDMAUDIOFILETYPE_UNKNOWN = 0,
+ /** Raw (PCM) file. */
+ PDMAUDIOFILETYPE_RAW,
+ /** Wave (.WAV) file. */
+ PDMAUDIOFILETYPE_WAV,
+ /** Hack to blow the type up to 32-bit. */
+ PDMAUDIOFILETYPE_32BIT_HACK = 0x7fffffff
+} PDMAUDIOFILETYPE;
+
+typedef uint32_t PDMAUDIOFILENAMEFLAGS;
+
+/** No flags defined. */
+#define PDMAUDIOFILENAME_FLAG_NONE 0
+/** Adds an ISO timestamp to the file name. */
+#define PDMAUDIOFILENAME_FLAG_TS RT_BIT(0)
+
+/**
+ * Structure for an audio file handle.
+ */
+typedef struct PDMAUDIOFILE
+{
+ /** Type of the audio file. */
+ PDMAUDIOFILETYPE enmType;
+ /** Audio file flags. */
+ PDMAUDIOFILEFLAGS fFlags;
+ /** File name and path. */
+ char szName[RTPATH_MAX + 1];
+ /** Actual file handle. */
+ RTFILE hFile;
+ /** Data needed for the specific audio file type implemented.
+ * Optional, can be NULL. */
+ void *pvData;
+ /** Data size (in bytes). */
+ size_t cbData;
+} PDMAUDIOFILE, *PPDMAUDIOFILE;
+
+/** Stream status flag. To be used with PDMAUDIOSTRMSTS_FLAG_ flags. */
+typedef uint32_t PDMAUDIOSTREAMSTS;
+
+/** No flags being set. */
+#define PDMAUDIOSTREAMSTS_FLAG_NONE 0
+/** Whether this stream has been initialized by the
+ * backend or not. */
+#define PDMAUDIOSTREAMSTS_FLAG_INITIALIZED RT_BIT_32(0)
+/** Whether this stream is enabled or disabled. */
+#define PDMAUDIOSTREAMSTS_FLAG_ENABLED RT_BIT_32(1)
+/** Whether this stream has been paused or not. This also implies
+ * that this is an enabled stream! */
+#define PDMAUDIOSTREAMSTS_FLAG_PAUSED RT_BIT_32(2)
+/** Whether this stream was marked as being disabled
+ * but there are still associated guest output streams
+ * which rely on its data. */
+#define PDMAUDIOSTREAMSTS_FLAG_PENDING_DISABLE RT_BIT_32(3)
+/** Whether this stream is in re-initialization phase.
+ * All other bits remain untouched to be able to restore
+ * the stream's state after the re-initialization bas been
+ * finished. */
+#define PDMAUDIOSTREAMSTS_FLAG_PENDING_REINIT RT_BIT_32(4)
+/** Validation mask. */
+#define PDMAUDIOSTREAMSTS_VALID_MASK UINT32_C(0x0000001F)
+
+/**
+ * Enumeration presenting a backend's current status.
+ */
+typedef enum PDMAUDIOBACKENDSTS
+{
+ /** Unknown/invalid status. */
+ PDMAUDIOBACKENDSTS_UNKNOWN = 0,
+ /** No backend attached. */
+ PDMAUDIOBACKENDSTS_NOT_ATTACHED,
+ /** The backend is in its initialization phase.
+ * Not all backends support this status. */
+ PDMAUDIOBACKENDSTS_INITIALIZING,
+ /** The backend has stopped its operation. */
+ PDMAUDIOBACKENDSTS_STOPPED,
+ /** The backend is up and running. */
+ PDMAUDIOBACKENDSTS_RUNNING,
+ /** The backend ran into an error and is unable to recover.
+ * A manual re-initialization might help. */
+ PDMAUDIOBACKENDSTS_ERROR,
+ /** Hack to blow the type up to 32-bit. */
+ PDMAUDIOBACKENDSTS_32BIT_HACK = 0x7fffffff
+} PDMAUDIOBACKENDSTS;
+
+/**
+ * Structure for keeping audio input stream specifics.
+ * Do not use directly. Instead, use PDMAUDIOSTREAM.
+ */
+typedef struct PDMAUDIOSTREAMIN
+{
+#ifdef VBOX_WITH_STATISTICS
+ struct
+ {
+ STAMCOUNTER TotalFramesCaptured;
+ STAMCOUNTER AvgFramesCaptured;
+ STAMCOUNTER TotalTimesCaptured;
+ STAMCOUNTER TotalFramesRead;
+ STAMCOUNTER AvgFramesRead;
+ STAMCOUNTER TotalTimesRead;
+ } Stats;
+#endif
+ struct
+ {
+ /** File for writing stream reads. */
+ PPDMAUDIOFILE pFileStreamRead;
+ /** File for writing non-interleaved captures. */
+ PPDMAUDIOFILE pFileCaptureNonInterleaved;
+ } Dbg;
+} PDMAUDIOSTREAMIN, *PPDMAUDIOSTREAMIN;
+
+/**
+ * Structure for keeping audio output stream specifics.
+ * Do not use directly. Instead, use PDMAUDIOSTREAM.
+ */
+typedef struct PDMAUDIOSTREAMOUT
+{
+#ifdef VBOX_WITH_STATISTICS
+ struct
+ {
+ STAMCOUNTER TotalFramesPlayed;
+ STAMCOUNTER AvgFramesPlayed;
+ STAMCOUNTER TotalTimesPlayed;
+ STAMCOUNTER TotalFramesWritten;
+ STAMCOUNTER AvgFramesWritten;
+ STAMCOUNTER TotalTimesWritten;
+ } Stats;
+#endif
+ struct
+ {
+ /** File for writing stream writes. */
+ PPDMAUDIOFILE pFileStreamWrite;
+ /** File for writing stream playback. */
+ PPDMAUDIOFILE pFilePlayNonInterleaved;
+ } Dbg;
+} PDMAUDIOSTREAMOUT, *PPDMAUDIOSTREAMOUT;
+
+/** Pointer to an audio stream. */
+typedef struct PDMAUDIOSTREAM *PPDMAUDIOSTREAM;
+
+/**
+ * Audio stream context.
+ * Needed for separating data from the guest and host side (per stream).
+ */
+typedef struct PDMAUDIOSTREAMCTX
+{
+ /** The stream's audio configuration. */
+ PDMAUDIOSTREAMCFG Cfg;
+ /** This stream's mixing buffer. */
+ PDMAUDIOMIXBUF MixBuf;
+} PDMAUDIOSTREAMCTX;
+
+/** Pointer to an audio stream context. */
+typedef struct PDMAUDIOSTREAM *PPDMAUDIOSTREAMCTX;
+
+/**
+ * Structure for maintaining an input/output audio stream.
+ */
+typedef struct PDMAUDIOSTREAM
+{
+ /** List node. */
+ RTLISTNODE Node;
+ /** Name of this stream. */
+ char szName[64];
+ /** Number of references to this stream. Only can be
+ * destroyed if the reference count is reaching 0. */
+ uint32_t cRefs;
+ /** Stream status flag. */
+ PDMAUDIOSTREAMSTS fStatus;
+ /** Audio direction of this stream. */
+ PDMAUDIODIR enmDir;
+ /** The guest side of the stream. */
+ PDMAUDIOSTREAMCTX Guest;
+ /** The host side of the stream. */
+ PDMAUDIOSTREAMCTX Host;
+ /** Union for input/output specifics (based on enmDir). */
+ union
+ {
+ PDMAUDIOSTREAMIN In;
+ PDMAUDIOSTREAMOUT Out;
+ } RT_UNION_NM(u);
+ /** Timestamp (in ns) since last iteration. */
+ uint64_t tsLastIteratedNs;
+ /** Timestamp (in ns) since last playback / capture. */
+ uint64_t tsLastPlayedCapturedNs;
+ /** Timestamp (in ns) since last read (input streams) or
+ * write (output streams). */
+ uint64_t tsLastReadWrittenNs;
+ /** For output streams this indicates whether the stream has reached
+ * its playback threshold, e.g. is playing audio.
+ * For input streams this indicates whether the stream has enough input
+ * data to actually start reading audio. */
+ bool fThresholdReached;
+ /** Data to backend-specific stream data.
+ * This data block will be casted by the backend to access its backend-dependent data.
+ *
+ * That way the backends do not have access to the audio connector's data. */
+ void *pvBackend;
+ /** Size (in bytes) of the backend-specific stream data. */
+ size_t cbBackend;
+} PDMAUDIOSTREAM;
+
+/** Pointer to a audio connector interface. */
+typedef struct PDMIAUDIOCONNECTOR *PPDMIAUDIOCONNECTOR;
+
+/**
+ * Enumeration for an audio callback source.
+ */
+typedef enum PDMAUDIOCBSOURCE
+{
+ /** Invalid, do not use. */
+ PDMAUDIOCBSOURCE_INVALID = 0,
+ /** Device emulation. */
+ PDMAUDIOCBSOURCE_DEVICE = 1,
+ /** Audio connector interface. */
+ PDMAUDIOCBSOURCE_CONNECTOR = 2,
+ /** Backend (lower). */
+ PDMAUDIOCBSOURCE_BACKEND = 3,
+ /** Hack to blow the type up to 32-bit. */
+ PDMAUDIOCBSOURCE_32BIT_HACK = 0x7fffffff
+} PDMAUDIOCBSOURCE;
+
+/**
+ * Audio device callback types.
+ * Those callbacks are being sent from the audio connector -> device emulation.
+ */
+typedef enum PDMAUDIODEVICECBTYPE
+{
+ /** Invalid, do not use. */
+ PDMAUDIODEVICECBTYPE_INVALID = 0,
+ /** Data is availabe as input for passing to the device emulation. */
+ PDMAUDIODEVICECBTYPE_DATA_INPUT,
+ /** Free data for the device emulation to write to the backend. */
+ PDMAUDIODEVICECBTYPE_DATA_OUTPUT,
+ /** Hack to blow the type up to 32-bit. */
+ PDMAUDIODEVICECBTYPE_32BIT_HACK = 0x7fffffff
+} PDMAUDIODEVICECBTYPE;
+
+/**
+ * Device callback data for audio input.
+ */
+typedef struct PDMAUDIODEVICECBDATA_DATA_INPUT
+{
+ /** Input: How many bytes are availabe as input for passing
+ * to the device emulation. */
+ uint32_t cbInAvail;
+ /** Output: How many bytes have been read. */
+ uint32_t cbOutRead;
+} PDMAUDIODEVICECBDATA_DATA_INPUT, *PPDMAUDIODEVICECBDATA_DATA_INPUT;
+
+/**
+ * Device callback data for audio output.
+ */
+typedef struct PDMAUDIODEVICECBDATA_DATA_OUTPUT
+{
+ /** Input: How many bytes are free for the device emulation to write. */
+ uint32_t cbInFree;
+ /** Output: How many bytes were written by the device emulation. */
+ uint32_t cbOutWritten;
+} PDMAUDIODEVICECBDATA_DATA_OUTPUT, *PPDMAUDIODEVICECBDATA_DATA_OUTPUT;
+
+/**
+ * Audio backend callback types.
+ * Those callbacks are being sent from the backend -> audio connector.
+ */
+typedef enum PDMAUDIOBACKENDCBTYPE
+{
+ /** Invalid, do not use. */
+ PDMAUDIOBACKENDCBTYPE_INVALID = 0,
+ /** The backend's status has changed. */
+ PDMAUDIOBACKENDCBTYPE_STATUS,
+ /** One or more host audio devices have changed. */
+ PDMAUDIOBACKENDCBTYPE_DEVICES_CHANGED,
+ /** Hack to blow the type up to 32-bit. */
+ PDMAUDIOBACKENDCBTYPE_32BIT_HACK = 0x7fffffff
+} PDMAUDIOBACKENDCBTYPE;
+
+/** Pointer to a host audio interface. */
+typedef struct PDMIHOSTAUDIO *PPDMIHOSTAUDIO;
+
+/**
+ * Host audio callback function.
+ * This function will be called from a backend to communicate with the host audio interface.
+ *
+ * @returns IPRT status code.
+ * @param pDrvIns Pointer to driver instance which called us.
+ * @param enmType Callback type.
+ * @param pvUser User argument.
+ * @param cbUser Size (in bytes) of user argument.
+ */
+typedef DECLCALLBACK(int) FNPDMHOSTAUDIOCALLBACK(PPDMDRVINS pDrvIns, PDMAUDIOBACKENDCBTYPE enmType, void *pvUser, size_t cbUser);
+/** Pointer to a FNPDMHOSTAUDIOCALLBACK(). */
+typedef FNPDMHOSTAUDIOCALLBACK *PFNPDMHOSTAUDIOCALLBACK;
+
+/**
+ * Audio callback registration record.
+ */
+typedef struct PDMAUDIOCBRECORD
+{
+ /** List node. */
+ RTLISTANCHOR Node;
+ /** Callback source. */
+ PDMAUDIOCBSOURCE enmSource;
+ /** Callback type, based on the given source. */
+ union
+ {
+ /** Device callback stuff. */
+ struct
+ {
+ PDMAUDIODEVICECBTYPE enmType;
+ } Device;
+ } RT_UNION_NM(u);
+ /** Pointer to context data. Optional. */
+ void *pvCtx;
+ /** Size (in bytes) of context data.
+ * Must be 0 if pvCtx is NULL. */
+ size_t cbCtx;
+} PDMAUDIOCBRECORD, *PPDMAUDIOCBRECORD;
+
+#define PPDMAUDIOBACKENDSTREAM void *
+
+/**
+ * Audio connector interface (up).
+ */
+typedef struct PDMIAUDIOCONNECTOR
+{
+ /**
+ * Enables or disables the given audio direction for this driver.
+ *
+ * When disabled, assiociated output streams consume written audio without passing them further down to the backends.
+ * Associated input streams then return silence when read from those.
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param enmDir Audio direction to enable or disable driver for.
+ * @param fEnable Whether to enable or disable the specified audio direction.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnEnable, (PPDMIAUDIOCONNECTOR pInterface, PDMAUDIODIR enmDir, bool fEnable));
+
+ /**
+ * Returns whether the given audio direction for this driver is enabled or not.
+ *
+ * @returns True if audio is enabled for the given direction, false if not.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param enmDir Audio direction to retrieve enabled status for.
+ */
+ DECLR3CALLBACKMEMBER(bool, pfnIsEnabled, (PPDMIAUDIOCONNECTOR pInterface, PDMAUDIODIR enmDir));
+
+ /**
+ * Retrieves the current configuration of the host audio backend.
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pCfg Where to store the host audio backend configuration data.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnGetConfig, (PPDMIAUDIOCONNECTOR pInterface, PPDMAUDIOBACKENDCFG pCfg));
+
+ /**
+ * Retrieves the current status of the host audio backend.
+ *
+ * @returns Status of the host audio backend.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param enmDir Audio direction to check host audio backend for. Specify PDMAUDIODIR_ANY for the overall
+ * backend status.
+ */
+ DECLR3CALLBACKMEMBER(PDMAUDIOBACKENDSTS, pfnGetStatus, (PPDMIAUDIOCONNECTOR pInterface, PDMAUDIODIR enmDir));
+
+ /**
+ * Creates an audio stream.
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pCfgHost Stream configuration for host side.
+ * @param pCfgGuest Stream configuration for guest side.
+ * @param ppStream Pointer where to return the created audio stream on success.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnStreamCreate, (PPDMIAUDIOCONNECTOR pInterface, PPDMAUDIOSTREAMCFG pCfgHost, PPDMAUDIOSTREAMCFG pCfgGuest, PPDMAUDIOSTREAM *ppStream));
+
+ /**
+ * Destroys an audio stream.
+ *
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnStreamDestroy, (PPDMIAUDIOCONNECTOR pInterface, PPDMAUDIOSTREAM pStream));
+
+ /**
+ * Adds a reference to the specified audio stream.
+ *
+ * @returns New reference count. UINT32_MAX on error.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream adding the reference to.
+ */
+ DECLR3CALLBACKMEMBER(uint32_t, pfnStreamRetain, (PPDMIAUDIOCONNECTOR pInterface, PPDMAUDIOSTREAM pStream));
+
+ /**
+ * Releases a reference from the specified stream.
+ *
+ * @returns New reference count. UINT32_MAX on error.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream releasing a reference from.
+ */
+ DECLR3CALLBACKMEMBER(uint32_t, pfnStreamRelease, (PPDMIAUDIOCONNECTOR pInterface, PPDMAUDIOSTREAM pStream));
+
+ /**
+ * Reads PCM audio data from the host (input).
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream to write to.
+ * @param pvBuf Where to store the read data.
+ * @param cbBuf Number of bytes to read.
+ * @param pcbRead Bytes of audio data read. Optional.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnStreamRead, (PPDMIAUDIOCONNECTOR pInterface, PPDMAUDIOSTREAM pStream, void *pvBuf, uint32_t cbBuf, uint32_t *pcbRead));
+
+ /**
+ * Writes PCM audio data to the host (output).
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream to read from.
+ * @param pvBuf Audio data to be written.
+ * @param cbBuf Number of bytes to be written.
+ * @param pcbWritten Bytes of audio data written. Optional.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnStreamWrite, (PPDMIAUDIOCONNECTOR pInterface, PPDMAUDIOSTREAM pStream, const void *pvBuf, uint32_t cbBuf, uint32_t *pcbWritten));
+
+ /**
+ * Controls a specific audio stream.
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ * @param enmStreamCmd The stream command to issue.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnStreamControl, (PPDMIAUDIOCONNECTOR pInterface, PPDMAUDIOSTREAM pStream, PDMAUDIOSTREAMCMD enmStreamCmd));
+
+ /**
+ * Processes stream data.
+ *
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnStreamIterate, (PPDMIAUDIOCONNECTOR pInterface, PPDMAUDIOSTREAM pStream));
+
+ /**
+ * Returns the number of readable data (in bytes) of a specific audio input stream.
+ *
+ * @returns Number of readable data (in bytes).
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ */
+ DECLR3CALLBACKMEMBER(uint32_t, pfnStreamGetReadable, (PPDMIAUDIOCONNECTOR pInterface, PPDMAUDIOSTREAM pStream));
+
+ /**
+ * Returns the number of writable data (in bytes) of a specific audio output stream.
+ *
+ * @returns Number of writable data (in bytes).
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ */
+ DECLR3CALLBACKMEMBER(uint32_t, pfnStreamGetWritable, (PPDMIAUDIOCONNECTOR pInterface, PPDMAUDIOSTREAM pStream));
+
+ /**
+ * Returns the status of a specific audio stream.
+ *
+ * @returns Audio stream status
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ */
+ DECLR3CALLBACKMEMBER(PDMAUDIOSTREAMSTS, pfnStreamGetStatus, (PPDMIAUDIOCONNECTOR pInterface, PPDMAUDIOSTREAM pStream));
+
+ /**
+ * Sets the audio volume of a specific audio stream.
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ * @param pVol Pointer to audio volume structure to set the stream's audio volume to.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnStreamSetVolume, (PPDMIAUDIOCONNECTOR pInterface, PPDMAUDIOSTREAM pStream, PPDMAUDIOVOLUME pVol));
+
+ /**
+ * Plays (transfers) available audio frames to the host backend. Only works with output streams.
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ * @param pcFramesPlayed Number of frames played. Optional.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnStreamPlay, (PPDMIAUDIOCONNECTOR pInterface, PPDMAUDIOSTREAM pStream, uint32_t *pcFramesPlayed));
+
+ /**
+ * Captures (transfers) available audio frames from the host backend. Only works with input streams.
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ * @param pcFramesCaptured Number of frames captured. Optional.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnStreamCapture, (PPDMIAUDIOCONNECTOR pInterface, PPDMAUDIOSTREAM pStream, uint32_t *pcFramesCaptured));
+
+ /**
+ * Registers (device) callbacks.
+ * This is handy for letting the device emulation know of certain events, e.g. processing input / output data
+ * or configuration changes.
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param paCallbacks Pointer to array of callbacks to register.
+ * @param cCallbacks Number of callbacks to register.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnRegisterCallbacks, (PPDMIAUDIOCONNECTOR pInterface, PPDMAUDIOCBRECORD paCallbacks, size_t cCallbacks));
+
+} PDMIAUDIOCONNECTOR;
+
+/** PDMIAUDIOCONNECTOR interface ID. */
+#define PDMIAUDIOCONNECTOR_IID "A643B40C-733F-4307-9549-070AF0EE0ED6"
+
+/**
+ * Assigns all needed interface callbacks for an audio backend.
+ *
+ * @param a_Prefix The function name prefix.
+ */
+#define PDMAUDIO_IHOSTAUDIO_CALLBACKS(a_Prefix) \
+ do { \
+ pThis->IHostAudio.pfnInit = RT_CONCAT(a_Prefix,Init); \
+ pThis->IHostAudio.pfnShutdown = RT_CONCAT(a_Prefix,Shutdown); \
+ pThis->IHostAudio.pfnGetConfig = RT_CONCAT(a_Prefix,GetConfig); \
+ /** @todo Add pfnGetDevices here as soon as supported by all backends. */ \
+ pThis->IHostAudio.pfnGetStatus = RT_CONCAT(a_Prefix,GetStatus); \
+ /** @todo Ditto for pfnSetCallback. */ \
+ pThis->IHostAudio.pfnStreamCreate = RT_CONCAT(a_Prefix,StreamCreate); \
+ pThis->IHostAudio.pfnStreamDestroy = RT_CONCAT(a_Prefix,StreamDestroy); \
+ pThis->IHostAudio.pfnStreamControl = RT_CONCAT(a_Prefix,StreamControl); \
+ pThis->IHostAudio.pfnStreamGetReadable = RT_CONCAT(a_Prefix,StreamGetReadable); \
+ pThis->IHostAudio.pfnStreamGetWritable = RT_CONCAT(a_Prefix,StreamGetWritable); \
+ pThis->IHostAudio.pfnStreamGetStatus = RT_CONCAT(a_Prefix,StreamGetStatus); \
+ pThis->IHostAudio.pfnStreamIterate = RT_CONCAT(a_Prefix,StreamIterate); \
+ pThis->IHostAudio.pfnStreamPlay = RT_CONCAT(a_Prefix,StreamPlay); \
+ pThis->IHostAudio.pfnStreamCapture = RT_CONCAT(a_Prefix,StreamCapture); \
+ } while (0)
+
+/**
+ * PDM host audio interface.
+ */
+typedef struct PDMIHOSTAUDIO
+{
+ /**
+ * Initializes the host backend (driver).
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnInit, (PPDMIHOSTAUDIO pInterface));
+
+ /**
+ * Shuts down the host backend (driver).
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ */
+ DECLR3CALLBACKMEMBER(void, pfnShutdown, (PPDMIHOSTAUDIO pInterface));
+
+ /**
+ * Returns the host backend's configuration (backend).
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pBackendCfg Where to store the backend audio configuration to.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnGetConfig, (PPDMIHOSTAUDIO pInterface, PPDMAUDIOBACKENDCFG pBackendCfg));
+
+ /**
+ * Returns (enumerates) host audio device information.
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pDeviceEnum Where to return the enumerated audio devices.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnGetDevices, (PPDMIHOSTAUDIO pInterface, PPDMAUDIODEVICEENUM pDeviceEnum));
+
+ /**
+ * Returns the current status from the audio backend.
+ *
+ * @returns PDMAUDIOBACKENDSTS enum.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param enmDir Audio direction to get status for. Pass PDMAUDIODIR_ANY for overall status.
+ */
+ DECLR3CALLBACKMEMBER(PDMAUDIOBACKENDSTS, pfnGetStatus, (PPDMIHOSTAUDIO pInterface, PDMAUDIODIR enmDir));
+
+ /**
+ * Sets a callback the audio backend can call. Optional.
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pfnCallback The callback function to use, or NULL when unregistering.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnSetCallback, (PPDMIHOSTAUDIO pInterface, PFNPDMHOSTAUDIOCALLBACK pfnCallback));
+
+ /**
+ * Creates an audio stream using the requested stream configuration.
+ * If a backend is not able to create this configuration, it will return its best match in the acquired configuration
+ * structure on success.
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ * @param pCfgReq Pointer to requested stream configuration.
+ * @param pCfgAcq Pointer to acquired stream configuration.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnStreamCreate, (PPDMIHOSTAUDIO pInterface, PPDMAUDIOBACKENDSTREAM pStream, PPDMAUDIOSTREAMCFG pCfgReq, PPDMAUDIOSTREAMCFG pCfgAcq));
+
+ /**
+ * Destroys an audio stream.
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnStreamDestroy, (PPDMIHOSTAUDIO pInterface, PPDMAUDIOBACKENDSTREAM pStream));
+
+ /**
+ * Controls an audio stream.
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ * @param enmStreamCmd The stream command to issue.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnStreamControl, (PPDMIHOSTAUDIO pInterface, PPDMAUDIOBACKENDSTREAM pStream, PDMAUDIOSTREAMCMD enmStreamCmd));
+
+ /**
+ * Returns the amount which is readable from the audio (input) stream.
+ *
+ * @returns For non-raw layout streams: Number of readable bytes.
+ * for raw layout streams : Number of readable audio frames.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ */
+ DECLR3CALLBACKMEMBER(uint32_t, pfnStreamGetReadable, (PPDMIHOSTAUDIO pInterface, PPDMAUDIOBACKENDSTREAM pStream));
+
+ /**
+ * Returns the amount which is writable to the audio (output) stream.
+ *
+ * @returns For non-raw layout streams: Number of writable bytes.
+ * for raw layout streams : Number of writable audio frames.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ */
+ DECLR3CALLBACKMEMBER(uint32_t, pfnStreamGetWritable, (PPDMIHOSTAUDIO pInterface, PPDMAUDIOBACKENDSTREAM pStream));
+
+ /**
+ * Returns the amount which is pending (in other words has not yet been processed) by/from the backend yet.
+ * Optional.
+ *
+ * For input streams this is read audio data by the backend which has not been processed by the host yet.
+ * For output streams this is written audio data to the backend which has not been processed by the backend yet.
+ *
+ * @returns For non-raw layout streams: Number of pending bytes.
+ * for raw layout streams : Number of pending audio frames.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ */
+ DECLR3CALLBACKMEMBER(uint32_t, pfnStreamGetPending, (PPDMIHOSTAUDIO pInterface, PPDMAUDIOBACKENDSTREAM pStream));
+
+ /**
+ * Returns the current status of the given backend stream.
+ *
+ * @returns PDMAUDIOSTREAMSTS
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ */
+ DECLR3CALLBACKMEMBER(PDMAUDIOSTREAMSTS, pfnStreamGetStatus, (PPDMIHOSTAUDIO pInterface, PPDMAUDIOBACKENDSTREAM pStream));
+
+ /**
+ * Gives the host backend the chance to do some (necessary) iteration work.
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnStreamIterate, (PPDMIHOSTAUDIO pInterface, PPDMAUDIOBACKENDSTREAM pStream));
+
+ /**
+ * Signals the backend that the host wants to begin playing for this iteration. Optional.
+ *
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ */
+ DECLR3CALLBACKMEMBER(void, pfnStreamPlayBegin, (PPDMIHOSTAUDIO pInterface, PPDMAUDIOBACKENDSTREAM pStream));
+
+ /**
+ * Plays (writes to) an audio (output) stream.
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ * @param pvBuf Pointer to audio data buffer to play.
+ * @param cxBuf For non-raw layout streams: Size (in bytes) of audio data buffer,
+ * for raw layout streams : Size (in audio frames) of audio data buffer.
+ * @param pcxWritten For non-raw layout streams: Returns number of bytes written. Optional.
+ * for raw layout streams : Returns number of frames written. Optional.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnStreamPlay, (PPDMIHOSTAUDIO pInterface, PPDMAUDIOBACKENDSTREAM pStream, const void *pvBuf, uint32_t cxBuf, uint32_t *pcxWritten));
+
+ /**
+ * Signals the backend that the host finished playing for this iteration. Optional.
+ *
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ */
+ DECLR3CALLBACKMEMBER(void, pfnStreamPlayEnd, (PPDMIHOSTAUDIO pInterface, PPDMAUDIOBACKENDSTREAM pStream));
+
+ /**
+ * Signals the backend that the host wants to begin capturing for this iteration. Optional.
+ *
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ */
+ DECLR3CALLBACKMEMBER(void, pfnStreamCaptureBegin, (PPDMIHOSTAUDIO pInterface, PPDMAUDIOBACKENDSTREAM pStream));
+
+ /**
+ * Captures (reads from) an audio (input) stream.
+ *
+ * @returns VBox status code.
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ * @param pvBuf Buffer where to store read audio data.
+ * @param cxBuf For non-raw layout streams: Size (in bytes) of audio data buffer,
+ * for raw layout streams : Size (in audio frames) of audio data buffer.
+ * @param pcxRead For non-raw layout streams: Returns number of bytes read. Optional.
+ * for raw layout streams : Returns number of frames read. Optional.
+ */
+ DECLR3CALLBACKMEMBER(int, pfnStreamCapture, (PPDMIHOSTAUDIO pInterface, PPDMAUDIOBACKENDSTREAM pStream, void *pvBuf, uint32_t cxBuf, uint32_t *pcxRead));
+
+ /**
+ * Signals the backend that the host finished capturing for this iteration. Optional.
+ *
+ * @param pInterface Pointer to the interface structure containing the called function pointer.
+ * @param pStream Pointer to audio stream.
+ */
+ DECLR3CALLBACKMEMBER(void, pfnStreamCaptureEnd, (PPDMIHOSTAUDIO pInterface, PPDMAUDIOBACKENDSTREAM pStream));
+
+} PDMIHOSTAUDIO;
+
+/** PDMIHOSTAUDIO interface ID. */
+#define PDMIHOSTAUDIO_IID "640F5A31-8245-491C-538F-29A0F9D08881"
+
+/** @} */
+
+#endif /* !VBOX_INCLUDED_vmm_pdmaudioifs_h */
+