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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_FILTERS_NULL_AUDIO_RENDERER_H_
#define MEDIA_FILTERS_NULL_AUDIO_RENDERER_H_
// NullAudioSink effectively uses an extra thread to "throw away" the
// audio data at a rate resembling normal playback speed. It's just like
// decoding to /dev/null!
//
// NullAudioSink can also be used in situations where the client has no
// audio device or we haven't written an audio implementation for a particular
// platform yet.
#include <vector>
#include "base/md5.h"
#include "base/threading/thread.h"
#include "media/base/audio_renderer_sink.h"
namespace media {
class MEDIA_EXPORT NullAudioSink
: NON_EXPORTED_BASE(public AudioRendererSink) {
public:
NullAudioSink();
// AudioRendererSink implementation.
virtual void Initialize(const AudioParameters& params,
RenderCallback* callback) OVERRIDE;
virtual void Start() OVERRIDE;
virtual void Stop() OVERRIDE;
virtual void Pause(bool flush) OVERRIDE;
virtual void Play() OVERRIDE;
virtual void SetPlaybackRate(float rate) OVERRIDE;
virtual bool SetVolume(double volume) OVERRIDE;
// Enables audio frame hashing and reinitializes the MD5 context. Must be
// called prior to Initialize().
void StartAudioHashForTesting();
// Returns the MD5 hash of all audio frames seen since the last reset.
std::string GetAudioHashForTesting();
protected:
virtual ~NullAudioSink();
private:
// Audio thread task that periodically calls FillBuffer() to consume
// audio data.
void FillBufferTask();
void SetPlaying(bool is_playing);
// A buffer passed to FillBuffer to advance playback.
std::vector<float*> audio_data_;
AudioParameters params_;
bool initialized_;
float playback_rate_;
bool playing_;
RenderCallback* callback_;
// Separate thread used to throw away data.
base::Thread thread_;
base::Lock lock_;
// Controls whether or not a running MD5 hash is computed for audio frames.
bool hash_audio_for_testing_;
scoped_array<base::MD5Context> md5_channel_contexts_;
DISALLOW_COPY_AND_ASSIGN(NullAudioSink);
};
} // namespace media
#endif // MEDIA_FILTERS_NULL_AUDIO_RENDERER_H_
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