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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef MEDIA_AUDIO_AUDIO_OUTPUT_RESAMPLER_H_
#define MEDIA_AUDIO_AUDIO_OUTPUT_RESAMPLER_H_
#include "base/containers/flat_map.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "media/audio/audio_debug_recording_helper.h"
#include "media/audio/audio_io.h"
#include "media/audio/audio_output_dispatcher.h"
#include "media/base/audio_parameters.h"
namespace media {
class AudioManager;
class AudioOutputDispatcherImpl;
class OnMoreDataConverter;
// AudioOutputResampler is a browser-side resampling and buffering solution
// which ensures audio data is always output at given parameters. See the
// AudioConverter class for details on the conversion process.
//
// AOR works by intercepting the AudioSourceCallback provided to StartStream()
// and redirecting it through an AudioConverter instance.
//
// AOR will automatically fall back from AUDIO_PCM_LOW_LATENCY to
// AUDIO_PCM_LINEAR if the output device fails to open at the requested output
// parameters. If opening still fails, it will fallback to AUDIO_FAKE.
class MEDIA_EXPORT AudioOutputResampler : public AudioOutputDispatcher {
public:
// Callback type to register an AudioDebugRecorder.
using RegisterDebugRecordingSourceCallback =
base::RepeatingCallback<std::unique_ptr<AudioDebugRecorder>(
const AudioParameters&)>;
AudioOutputResampler(AudioManager* audio_manager,
const AudioParameters& input_params,
const AudioParameters& output_params,
const std::string& output_device_id,
base::TimeDelta close_delay,
const RegisterDebugRecordingSourceCallback&
register_debug_recording_source_callback);
AudioOutputResampler(const AudioOutputResampler&) = delete;
AudioOutputResampler& operator=(const AudioOutputResampler&) = delete;
~AudioOutputResampler() override;
// AudioOutputDispatcher interface.
AudioOutputProxy* CreateStreamProxy() override;
bool OpenStream() override;
bool StartStream(AudioOutputStream::AudioSourceCallback* callback,
AudioOutputProxy* stream_proxy) override;
void StopStream(AudioOutputProxy* stream_proxy) override;
void StreamVolumeSet(AudioOutputProxy* stream_proxy, double volume) override;
void CloseStream(AudioOutputProxy* stream_proxy) override;
void FlushStream(AudioOutputProxy* stream_proxy) override;
private:
using CallbackMap =
base::flat_map<AudioOutputProxy*, std::unique_ptr<OnMoreDataConverter>>;
// Used to reinitialize |dispatcher_| upon timeout if there are no open
// streams.
void Reinitialize();
// Used to initialize |dispatcher_|.
std::unique_ptr<AudioOutputDispatcherImpl> MakeDispatcher(
const std::string& output_device_id,
const AudioParameters& params);
// Stops the stream corresponding to the |item| in |callbacks_|.
void StopStreamInternal(const CallbackMap::value_type& item);
// Dispatcher to proxy all AudioOutputDispatcher calls too.
// Lazily initialized on a first stream open request.
std::unique_ptr<AudioOutputDispatcherImpl> dispatcher_;
// Map of outstanding OnMoreDataConverter objects. A new object is created
// on every StartStream() call and destroyed on CloseStream().
CallbackMap callbacks_;
// Used by AudioOutputDispatcherImpl; kept so we can reinitialize on the fly.
const base::TimeDelta close_delay_;
// Source AudioParameters.
const AudioParameters input_params_;
// AudioParameters used to setup the output stream; changed upon fallback.
AudioParameters output_params_;
// The original AudioParameters we were constructed with.
const AudioParameters original_output_params_;
// Output device id.
const std::string device_id_;
// The reinitialization timer provides a way to recover from temporary failure
// states by clearing the dispatcher if all proxies have been closed and none
// have been created within |close_delay_|. Without this, audio may be lost
// to a fake stream indefinitely for transient errors.
base::RetainingOneShotTimer reinitialize_timer_;
// Callback for registering a debug recording source.
RegisterDebugRecordingSourceCallback
register_debug_recording_source_callback_;
base::WeakPtrFactory<AudioOutputResampler> weak_factory_{this};
};
} // namespace media
#endif // MEDIA_AUDIO_AUDIO_OUTPUT_RESAMPLER_H_
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