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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_SINK_H_
#define MEDIA_BASE_AUDIO_RENDERER_SINK_H_
#include <stdint.h>
#include <string>
#include "base/callback.h"
#include "base/memory/ref_counted.h"
#include "media/base/audio_bus.h"
#include "media/base/audio_parameters.h"
#include "media/base/output_device_info.h"
namespace media {
// AudioRendererSink is an interface representing the end-point for
// rendered audio. An implementation is expected to
// periodically call Render() on a callback object.
class AudioRendererSink
: public base::RefCountedThreadSafe<media::AudioRendererSink> {
public:
class RenderCallback {
public:
// Attempts to completely fill all channels of |dest|, returns actual
// number of frames filled. |prior_frames_skipped| contains the number of
// frames
// the consumer has skipped, if any.
// The |delay| argument represents audio device output latency,
// |delay_timestamp| represents the time when |delay| was obtained.
virtual int Render(base::TimeDelta delay,
base::TimeTicks delay_timestamp,
int prior_frames_skipped,
AudioBus* dest) = 0;
// Signals an error has occurred.
virtual void OnRenderError() = 0;
protected:
virtual ~RenderCallback() {}
};
// Sets important information about the audio stream format.
// It must be called before any of the other methods.
virtual void Initialize(const AudioParameters& params,
RenderCallback* callback) = 0;
// Starts audio playback.
virtual void Start() = 0;
// Stops audio playback and performs cleanup. It must be called before
// destruction.
virtual void Stop() = 0;
// Pauses playback.
virtual void Pause() = 0;
// Resumes playback after calling Pause().
virtual void Play() = 0;
// Sets the playback volume, with range [0.0, 1.0] inclusive.
// Returns |true| on success.
virtual bool SetVolume(double volume) = 0;
// Returns current output device information. If the information is not
// available yet, this method may block until it becomes available.
// If the sink is not associated with any output device, |device_status| of
// OutputDeviceInfo should be set to OUTPUT_DEVICE_STATUS_ERROR_INTERNAL.
// Must never be called on the IO thread.
virtual OutputDeviceInfo GetOutputDeviceInfo() = 0;
// Returns |true| if a source with hardware parameters is preferable.
virtual bool IsOptimizedForHardwareParameters() = 0;
// If DCHECKs are enabled, this function returns true if called on rendering
// thread, otherwise false. With DCHECKs disabled, it returns true. Thus, it
// is intended to be used for DCHECKing.
virtual bool CurrentThreadIsRenderingThread() = 0;
protected:
friend class base::RefCountedThreadSafe<AudioRendererSink>;
virtual ~AudioRendererSink() {}
};
// Same as AudioRendererSink except that Initialize() and Start() can be called
// again after Stop().
// TODO(sandersd): Fold back into AudioRendererSink once all subclasses support
// this.
class RestartableAudioRendererSink : public AudioRendererSink {
protected:
~RestartableAudioRendererSink() override {}
};
class SwitchableAudioRendererSink : public RestartableAudioRendererSink {
public:
// Attempts to switch the audio output device associated with a sink.
// Once the attempt is finished, |callback| is invoked with the
// result of the operation passed as a parameter. The result is a value from
// the media::OutputDeviceStatus enum.
// There is no guarantee about the thread where |callback| will be invoked.
virtual void SwitchOutputDevice(const std::string& device_id,
OutputDeviceStatusCB callback) = 0;
protected:
~SwitchableAudioRendererSink() override {}
};
} // namespace media
#endif // MEDIA_BASE_AUDIO_RENDERER_SINK_H_