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 "TimeUnits.h"

#include "mozilla/ProfilerUtils.h"

#include "mozilla/RefPtr.h"

#include "mozilla/SPSCQueue.h"

#include "mozilla/SharedThreadPool.h"

#include "mozilla/Variant.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);

  // 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;

  struct Empty {};

  struct LatencyChangeData {

    media::TimeUnit mLatency;

};

  struct Data : public Variant<AudioChunk, LatencyChangeData, Empty> {

    Data() : Variant(AsVariant(Empty())) {}

    explicit Data(AudioChunk aChunk) : Variant(AsVariant(std::move(aChunk))) {}

    explicit Data(LatencyChangeData aLatencyChangeData)

        : Variant(AsVariant(std::move(aLatencyChangeData))) {}

};

  // 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<Data> mSPSCQueue{30};

};

}  // namespace mozilla

#endif  // DOM_MEDIA_AudioInputSource_H_