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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Audio rendering unit utilizing an AudioRendererSink to output data.
// This class lives inside three threads during it's lifetime, namely:
// 1. Render thread
// Where the object is created.
// 2. Media thread (provided via constructor)
// All AudioDecoder methods are called on this thread.
// 3. Audio thread created by the AudioRendererSink.
// Render() is called here where audio data is decoded into raw PCM data.
// AudioRendererImpl talks to an AudioRendererAlgorithm that takes care of
// queueing audio data and stretching/shrinking audio data when playback rate !=
// 1.0 or 0.0.
#include <stdint.h>
#include <deque>
#include "base/macros.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/synchronization/lock.h"
#include "media/base/audio_decoder.h"
#include "media/base/audio_renderer.h"
#include "media/base/audio_renderer_sink.h"
#include "media/base/decryptor.h"
#include "media/base/media_log.h"
#include "media/base/time_source.h"
#include "media/filters/audio_renderer_algorithm.h"
#include "media/filters/decoder_stream.h"
namespace base {
class SingleThreadTaskRunner;
class TickClock;
namespace media {
class AudioBufferConverter;
class AudioBus;
class AudioClock;
class AudioHardwareConfig;
class AudioSplicer;
class DecryptingDemuxerStream;
class MEDIA_EXPORT AudioRendererImpl
: public AudioRenderer,
public TimeSource,
NON_EXPORTED_BASE(public AudioRendererSink::RenderCallback) {
// |task_runner| is the thread on which AudioRendererImpl will execute.
// |sink| is used as the destination for the rendered audio.
// |decoders| contains the AudioDecoders to use when initializing.
const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
AudioRendererSink* sink,
ScopedVector<AudioDecoder> decoders,
const AudioHardwareConfig& hardware_config,
const scoped_refptr<MediaLog>& media_log);
~AudioRendererImpl() override;
// TimeSource implementation.
void StartTicking() override;
void StopTicking() override;
void SetPlaybackRate(double rate) override;
void SetMediaTime(base::TimeDelta time) override;
base::TimeDelta CurrentMediaTime() override;
bool GetWallClockTimes(
const std::vector<base::TimeDelta>& media_timestamps,
std::vector<base::TimeTicks>* wall_clock_times) override;
// AudioRenderer implementation.
void Initialize(DemuxerStream* stream,
const PipelineStatusCB& init_cb,
CdmContext* cdm_context,
const StatisticsCB& statistics_cb,
const BufferingStateCB& buffering_state_cb,
const base::Closure& ended_cb,
const PipelineStatusCB& error_cb,
const base::Closure& waiting_for_decryption_key_cb) override;
TimeSource* GetTimeSource() override;
void Flush(const base::Closure& callback) override;
void StartPlaying() override;
void SetVolume(float volume) override;
friend class AudioRendererImplTest;
// Important detail: being in kPlaying doesn't imply that audio is being
// rendered. Rather, it means that the renderer is ready to go. The actual
// rendering of audio is controlled via Start/StopRendering().
// kUninitialized
// | Initialize()
// |
// V
// kInitializing
// | Decoders initialized
// |
// V Decoders reset
// kFlushed <------------------ kFlushing
// | StartPlaying() ^
// | |
// | | Flush()
// `---------> kPlaying --------'
enum State {
// Callback from the audio decoder delivering decoded audio samples.
void DecodedAudioReady(AudioBufferStream::Status status,
const scoped_refptr<AudioBuffer>& buffer);
// Handles buffers that come out of |splicer_|.
// Returns true if more buffers are needed.
bool HandleSplicerBuffer_Locked(const scoped_refptr<AudioBuffer>& buffer);
// Helper functions for AudioDecoder::Status values passed to
// DecodedAudioReady().
void HandleAbortedReadOrDecodeError(bool is_decode_error);
void StartRendering_Locked();
void StopRendering_Locked();
// AudioRendererSink::RenderCallback implementation.
// NOTE: These are called on the audio callback thread!
// Render() fills the given buffer with audio data by delegating to its
// |algorithm_|. Render() also takes care of updating the clock.
// Returns the number of frames copied into |audio_bus|, which may be less
// than or equal to the initial number of frames in |audio_bus|
// If this method returns fewer frames than the initial number of frames in
// |audio_bus|, it could be a sign that the pipeline is stalled or unable to
// stream the data fast enough. In such scenarios, the callee should zero out
// unused portions of their buffer to play back silence.
// Render() updates the pipeline's playback timestamp. If Render() is
// not called at the same rate as audio samples are played, then the reported
// timestamp in the pipeline will be ahead of the actual audio playback. In
// this case |audio_delay_milliseconds| should be used to indicate when in the
// future should the filled buffer be played.
int Render(AudioBus* audio_bus,
uint32_t audio_delay_milliseconds,
uint32_t frames_skipped) override;
void OnRenderError() override;
// Helper methods that schedule an asynchronous read from the decoder as long
// as there isn't a pending read.
// Must be called on |task_runner_|.
void AttemptRead();
void AttemptRead_Locked();
bool CanRead_Locked();
void ChangeState_Locked(State new_state);
// Returns true if the data in the buffer is all before |start_timestamp_|.
// This can only return true while in the kPlaying state.
bool IsBeforeStartTime(const scoped_refptr<AudioBuffer>& buffer);
// Called upon AudioBufferStream initialization, or failure thereof (indicated
// by the value of |success|).
void OnAudioBufferStreamInitialized(bool succes);
// Used to initiate the flush operation once all pending reads have
// completed.
void DoFlush_Locked();
// Called when the |decoder_|.Reset() has completed.
void ResetDecoderDone();
// Called by the AudioBufferStream when a splice buffer is demuxed.
void OnNewSpliceBuffer(base::TimeDelta);
// Called by the AudioBufferStream when a config change occurs.
void OnConfigChange();
// Updates |buffering_state_| and fires |buffering_state_cb_|.
void SetBufferingState_Locked(BufferingState buffering_state);
scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
scoped_ptr<AudioSplicer> splicer_;
scoped_ptr<AudioBufferConverter> buffer_converter_;
// Whether or not we expect to handle config changes.
bool expecting_config_changes_;
// The sink (destination) for rendered audio. |sink_| must only be accessed
// on |task_runner_|. |sink_| must never be called under |lock_| or else we
// may deadlock between |task_runner_| and the audio callback thread.
scoped_refptr<media::AudioRendererSink> sink_;
scoped_ptr<AudioBufferStream> audio_buffer_stream_;
// Interface to the hardware audio params.
const AudioHardwareConfig& hardware_config_;
scoped_refptr<MediaLog> media_log_;
// Cached copy of hardware params from |hardware_config_|.
AudioParameters audio_parameters_;
// Callbacks provided during Initialize().
PipelineStatusCB init_cb_;
BufferingStateCB buffering_state_cb_;
base::Closure ended_cb_;
PipelineStatusCB error_cb_;
StatisticsCB statistics_cb_;
// Callback provided to Flush().
base::Closure flush_cb_;
// Overridable tick clock for testing.
scoped_ptr<base::TickClock> tick_clock_;
// Memory usage of |algorithm_| recorded during the last
// HandleSplicerBuffer_Locked() call.
int64_t last_audio_memory_usage_;
// After Initialize() has completed, all variables below must be accessed
// under |lock_|. ------------------------------------------------------------
base::Lock lock_;
// Algorithm for scaling audio.
double playback_rate_;
scoped_ptr<AudioRendererAlgorithm> algorithm_;
// Simple state tracking variable.
State state_;
BufferingState buffering_state_;
// Keep track of whether or not the sink is playing and whether we should be
// rendering.
bool rendering_;
bool sink_playing_;
// Keep track of our outstanding read to |decoder_|.
bool pending_read_;
// Keeps track of whether we received and rendered the end of stream buffer.
bool received_end_of_stream_;
bool rendered_end_of_stream_;
scoped_ptr<AudioClock> audio_clock_;
// The media timestamp to begin playback at after seeking. Set via
// SetMediaTime().
base::TimeDelta start_timestamp_;
// The media timestamp to signal end of audio playback. Determined during
// Render() when writing the final frames of decoded audio data.
base::TimeDelta ended_timestamp_;
// Set every Render() and used to provide an interpolated time value to
// CurrentMediaTimeForSyncingVideo().
base::TimeTicks last_render_time_;
// Set to the value of |last_render_time_| when StopRendering_Locked() is
// called for any reason. Cleared by the next successful Render() call after
// being used to adjust for lost time between the last call.
base::TimeTicks stop_rendering_time_;
// Set upon receipt of the first decoded buffer after a StartPlayingFrom().
// Used to determine how long to delay playback.
base::TimeDelta first_packet_timestamp_;
// End variables which must be accessed under |lock_|. ----------------------
// NOTE: Weak pointers must be invalidated before all other member variables.
base::WeakPtrFactory<AudioRendererImpl> weak_factory_;
} // namespace media