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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.
#ifndef MEDIA_BASE_AUDIO_RENDERER_H_
#define MEDIA_BASE_AUDIO_RENDERER_H_
#include "base/callback.h"
#include "base/memory/ref_counted.h"
#include "base/time/time.h"
#include "media/base/buffering_state.h"
#include "media/base/media_export.h"
#include "media/base/pipeline_status.h"
namespace media {
class DemuxerStream;
class MEDIA_EXPORT AudioRenderer {
public:
// First parameter is the current time that has been rendered.
// Second parameter is the maximum time value that the clock cannot exceed.
typedef base::Callback<void(base::TimeDelta, base::TimeDelta)> TimeCB;
// Used to indicate changes in the buffering state of this audio renderer.
typedef base::Callback<void(BufferingState)> BufferingStateCB;
AudioRenderer();
virtual ~AudioRenderer();
// Initialize an AudioRenderer with |stream|, executing |init_cb| upon
// completion.
//
// |statistics_cb| is executed periodically with audio rendering stats.
//
// |time_cb| is executed whenever time has advanced by way of audio rendering.
//
// |buffering_state_cb| is executed when audio rendering has either run out of
// data or has enough data to continue playback.
//
// |ended_cb| is executed when audio rendering has reached the end of stream.
//
// |error_cb| is executed if an error was encountered.
virtual void Initialize(DemuxerStream* stream,
const PipelineStatusCB& init_cb,
const StatisticsCB& statistics_cb,
const TimeCB& time_cb,
const BufferingStateCB& buffering_state_cb,
const base::Closure& ended_cb,
const PipelineStatusCB& error_cb) = 0;
// Signal audio playback to start at the current rate. It is expected that
// |time_cb| will eventually start being run with time updates.
virtual void StartRendering() = 0;
// Signal audio playback to stop until further notice. It is expected that
// |time_cb| will no longer be run.
virtual void StopRendering() = 0;
// Discard any audio data, executing |callback| when completed.
//
// Clients should expect |buffering_state_cb| to be called with
// BUFFERING_HAVE_NOTHING while flushing is in progress.
virtual void Flush(const base::Closure& callback) = 0;
// Starts playback by reading from |stream| and decoding and rendering audio.
// |timestamp| is the media timestamp playback should start rendering from.
//
// Only valid to call after a successful Initialize() or Flush().
virtual void StartPlayingFrom(base::TimeDelta timestamp) = 0;
// Stop all operations in preparation for being deleted, executing |callback|
// when complete.
virtual void Stop(const base::Closure& callback) = 0;
// Updates the current playback rate.
virtual void SetPlaybackRate(float playback_rate) = 0;
// Sets the output volume.
virtual void SetVolume(float volume) = 0;
private:
DISALLOW_COPY_AND_ASSIGN(AudioRenderer);
};
} // namespace media
#endif // MEDIA_BASE_AUDIO_RENDERER_H_
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