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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_MIXER_H_
#define MEDIA_BASE_AUDIO_RENDERER_MIXER_H_
#include <set>
#include "base/synchronization/lock.h"
#include "media/base/audio_renderer_mixer_input.h"
#include "media/base/audio_renderer_sink.h"
#include "media/base/multi_channel_resampler.h"
namespace media {
// Mixes a set of AudioRendererMixerInputs into a single output stream which is
// funneled into a single shared AudioRendererSink; saving a bundle on renderer
// side resources. Resampling is done post-mixing as it is the most expensive
// process. If the input sample rate matches the audio hardware sample rate, no
// resampling is done.
class MEDIA_EXPORT AudioRendererMixer
: NON_EXPORTED_BASE(public AudioRendererSink::RenderCallback) {
public:
AudioRendererMixer(const AudioParameters& input_params,
const AudioParameters& output_params,
const scoped_refptr<AudioRendererSink>& sink);
virtual ~AudioRendererMixer();
// Add or remove a mixer input from mixing; called by AudioRendererMixerInput.
void AddMixerInput(const scoped_refptr<AudioRendererMixerInput>& input);
void RemoveMixerInput(const scoped_refptr<AudioRendererMixerInput>& input);
private:
// AudioRendererSink::RenderCallback implementation.
virtual int Render(AudioBus* audio_bus,
int audio_delay_milliseconds) OVERRIDE;
virtual void OnRenderError() OVERRIDE;
// Handles mixing and volume adjustment. Fully fills |audio_bus| with mixed
// audio data. When resampling is necessary, ProvideInput() will be called
// by MultiChannelResampler when more data is necessary.
void ProvideInput(AudioBus* audio_bus);
// Output sink for this mixer.
scoped_refptr<AudioRendererSink> audio_sink_;
// Set of mixer inputs to be mixed by this mixer. Access is thread-safe
// through |mixer_inputs_lock_|.
typedef std::set< scoped_refptr<AudioRendererMixerInput> >
AudioRendererMixerInputSet;
AudioRendererMixerInputSet mixer_inputs_;
base::Lock mixer_inputs_lock_;
// Vector for rendering audio data from each mixer input.
scoped_ptr<AudioBus> mixer_input_audio_bus_;
// Handles resampling post-mixing.
scoped_ptr<MultiChannelResampler> resampler_;
// The audio delay in milliseconds received by the last Render() call.
int current_audio_delay_milliseconds_;
// Ratio of input data to output data. Used to scale audio delay information.
double io_ratio_;
double input_ms_per_frame_;
DISALLOW_COPY_AND_ASSIGN(AudioRendererMixer);
};
} // namespace media
#endif // MEDIA_BASE_AUDIO_RENDERER_MIXER_H_
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