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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.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;
AudioRenderer();
virtual ~AudioRenderer();
// Initialize an AudioRenderer with |stream|, executing |init_cb| upon
// completion.
//
// |statistics_cb| is executed periodically with audio rendering stats.
//
// |underflow_cb| is executed when the renderer runs out of data to pass to
// the audio card during playback. ResumeAfterUnderflow() must be called
// to resume playback. Pause(), Preroll(), or Stop() cancels the underflow
// condition.
//
// |time_cb| is executed whenever time has advanced by way of audio rendering.
//
// |ended_cb| is executed when audio rendering has reached the end of stream.
//
// |disabled_cb| is executed when audio rendering has been disabled due to
// external factors (i.e., device was removed). |time_cb| will no longer be
// executed. TODO(scherkus): this might not be needed http://crbug.com/234708
//
// |error_cb| is executed if an error was encountered.
virtual void Initialize(DemuxerStream* stream,
const PipelineStatusCB& init_cb,
const StatisticsCB& statistics_cb,
const base::Closure& underflow_cb,
const TimeCB& time_cb,
const base::Closure& ended_cb,
const base::Closure& disabled_cb,
const PipelineStatusCB& error_cb) = 0;
// Start audio decoding and rendering at the current playback rate, executing
// |callback| when playback is underway.
virtual void Play(const base::Closure& callback) = 0;
// Temporarily suspend decoding and rendering audio, executing |callback| when
// playback has been suspended.
virtual void Pause(const base::Closure& callback) = 0;
// Discard any audio data, executing |callback| when completed.
virtual void Flush(const base::Closure& callback) = 0;
// Start prerolling audio data for samples starting at |time|, executing
// |callback| when completed.
//
// Only valid to call after a successful Initialize() or Flush().
virtual void Preroll(base::TimeDelta time,
const PipelineStatusCB& callback) = 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;
// Resumes playback after underflow occurs.
virtual void ResumeAfterUnderflow() = 0;
private:
DISALLOW_COPY_AND_ASSIGN(AudioRenderer);
};
} // namespace media
#endif // MEDIA_BASE_AUDIO_RENDERER_H_
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