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// Copyright (c) 2011 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_AUDIO_SIMPLE_SOURCES_H_
#define MEDIA_AUDIO_SIMPLE_SOURCES_H_
#include <list>
#include "media/audio/audio_io.h"
#include "media/base/seekable_buffer.h"
// An audio source that produces a pure sinusoidal tone.
class MEDIA_EXPORT SineWaveAudioSource
: public AudioOutputStream::AudioSourceCallback {
public:
enum Format {
FORMAT_8BIT_LINEAR_PCM,
FORMAT_16BIT_LINEAR_PCM,
};
// |channels| is the number of audio channels, |freq| is the frequency in
// hertz and it has to be less than half of the sampling frequency
// |sample_freq| or else you will get aliasing.
SineWaveAudioSource(Format format, int channels,
double freq, double sample_freq);
virtual ~SineWaveAudioSource() {}
// Implementation of AudioSourceCallback.
virtual uint32 OnMoreData(
AudioOutputStream* stream, uint8* dest, uint32 max_size,
AudioBuffersState audio_buffers);
virtual void OnError(AudioOutputStream* stream, int code);
protected:
Format format_;
int channels_;
double freq_;
double sample_freq_;
};
// Defines an interface for pushing audio output. In contrast, the interfaces
// defined by AudioSourceCallback are pull model only.
class MEDIA_EXPORT PushAudioOutput {
public:
virtual ~PushAudioOutput() {}
// Write audio data to the audio device. It will be played eventually.
// Returns false on failure.
virtual bool Write(const void* data, uint32 len) = 0;
// Returns the number of bytes that have been buffered but not yet given
// to the audio device.
virtual uint32 UnProcessedBytes() = 0;
};
// A fairly basic class to connect a push model provider PushAudioOutput to
// a pull model provider AudioSourceCallback. Fundamentally it manages a series
// of audio buffers and is unaware of the actual audio format.
// Note that the PushSource is not thread safe and user need to provide locking.
class MEDIA_EXPORT PushSource
: public AudioOutputStream::AudioSourceCallback,
public PushAudioOutput {
public:
PushSource();
virtual ~PushSource();
// Write one buffer.
virtual bool Write(const void* data, uint32 len);
// Return the total number of bytes not given to the audio device yet.
virtual uint32 UnProcessedBytes();
// Implementation of AudioSourceCallback.
virtual uint32 OnMoreData(AudioOutputStream* stream, uint8* dest,
uint32 max_size, AudioBuffersState buffers_state);
virtual void OnError(AudioOutputStream* stream, int code);
// Discard all buffered data and reset to initial state.
void ClearAll();
private:
// Free acquired resources.
void CleanUp();
media::SeekableBuffer buffer_;
};
#endif // MEDIA_AUDIO_SIMPLE_SOURCES_H_
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