gecko-dev/dom/media/AudioSink.h

148 lines
4.5 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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 http://mozilla.org/MPL/2.0/. */
#if !defined(AudioSink_h__)
#define AudioSink_h__
#include "nsISupportsImpl.h"
#include "MediaDecoderReader.h"
#include "mozilla/dom/AudioChannelBinding.h"
namespace mozilla {
class AudioAvailableEventManager;
class AudioStream;
class MediaDecoderStateMachine;
class AudioSink {
public:
NS_INLINE_DECL_THREADSAFE_REFCOUNTING(AudioSink)
AudioSink(MediaDecoderStateMachine* aStateMachine,
int64_t aStartTime, AudioInfo aInfo, dom::AudioChannel aChannel);
nsresult Init();
int64_t GetPosition();
// Check whether we've pushed more frames to the audio hardware than it has
// played.
bool HasUnplayedFrames();
// Tell the AudioSink to stop processing and initiate shutdown. Must be
// called with the decoder monitor held.
void PrepareToShutdown();
// Shut down the AudioSink's resources. The decoder monitor must not be
// held during this call, as it may block processing thread event queues.
void Shutdown();
void SetVolume(double aVolume);
void SetPlaybackRate(double aPlaybackRate);
void SetPreservesPitch(bool aPreservesPitch);
void StartPlayback();
void StopPlayback();
private:
~AudioSink() {}
// The main loop for the audio thread. Sent to the thread as
// an nsRunnableMethod. This continually does blocking writes to
// to audio stream to play audio data.
void AudioLoop();
// Allocate and initialize mAudioStream. Returns NS_OK on success.
nsresult InitializeAudioStream();
void Drain();
void Cleanup();
bool ExpectMoreAudioData();
// Wait on the decoder monitor until playback is ready or the sink is told to shut down.
void WaitForAudioToPlay();
// Check if the sink has been told to shut down, resuming mAudioStream if
// not. Returns true if processing should continue, false if AudioLoop
// should shutdown.
bool IsPlaybackContinuing();
// Write aFrames of audio frames of silence to the audio hardware. Returns
// the number of frames actually written. The write size is capped at
// SILENCE_BYTES_CHUNK (32kB), so must be called in a loop to write the
// desired number of frames. This ensures that the playback position
// advances smoothly, and guarantees that we don't try to allocate an
// impossibly large chunk of memory in order to play back silence. Called
// on the audio thread.
uint32_t PlaySilence(uint32_t aFrames);
// Pops an audio chunk from the front of the audio queue, and pushes its
// audio data to the audio hardware. Called on the audio thread.
uint32_t PlayFromAudioQueue();
void UpdateStreamSettings();
// If we have already written enough frames to the AudioStream, start the
// playback.
void StartAudioStreamPlaybackIfNeeded();
void WriteSilence(uint32_t aFrames);
int64_t GetEndTime();
MediaQueue<AudioData>& AudioQueue();
ReentrantMonitor& GetReentrantMonitor();
void AssertCurrentThreadInMonitor();
void AssertOnAudioThread();
nsRefPtr<MediaDecoderStateMachine> mStateMachine;
// Thread for pushing audio onto the audio hardware.
// The "audio push thread".
nsCOMPtr<nsIThread> mThread;
// The audio stream resource. Used on the state machine, and audio threads.
// This is created and destroyed on the audio thread, while holding the
// decoder monitor, so if this is used off the audio thread, you must
// first acquire the decoder monitor and check that it is non-null.
nsRefPtr<AudioStream> mAudioStream;
// The presentation time of the first audio frame that was played in
// microseconds. We can add this to the audio stream position to determine
// the current audio time. Accessed on audio and state machine thread.
// Synchronized by decoder monitor.
int64_t mStartTime;
// PCM frames written to the stream so far.
int64_t mWritten;
// Keep the last good position returned from the audio stream. Used to ensure
// position returned by GetPosition() is mono-increasing in spite of audio
// stream error.
int64_t mLastGoodPosition;
AudioInfo mInfo;
dom::AudioChannel mChannel;
double mVolume;
double mPlaybackRate;
bool mPreservesPitch;
bool mStopAudioThread;
bool mSetVolume;
bool mSetPlaybackRate;
bool mSetPreservesPitch;
bool mPlaying;
};
} // namespace mozilla
#endif