content/public/renderer/media_stream_audio_renderer.h

// Copyright 2013 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 CONTENT_PUBLIC_RENDERER_MEDIA_STREAM_AUDIO_RENDERER_H_
#define CONTENT_PUBLIC_RENDERER_MEDIA_STREAM_AUDIO_RENDERER_H_

#include <string>

#include "base/callback.h"
#include "base/memory/ref_counted.h"
#include "base/time/time.h"
#include "media/base/output_device_info.h"
#include "url/origin.h"

namespace content {

class MediaStreamAudioRenderer
    : public base::RefCountedThreadSafe<MediaStreamAudioRenderer> {
 public:
  // Starts rendering audio.
  virtual void Start() = 0;

  // Stops rendering audio.
  virtual void Stop() = 0;

  // Resumes rendering audio after being paused.
  virtual void Play() = 0;

  // Temporarily suspends rendering audio. The audio stream might still be
  // active but new audio data is not provided to the consumer.
  virtual void Pause() = 0;

  // Sets the output volume.
  virtual void SetVolume(float volume) = 0;

  // Returns current output device information. If the information is not
  // available yet, this method may block until it becomes available.
  // If the renderer 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 media::OutputDeviceInfo GetOutputDeviceInfo() = 0;

  // Attempts to switch the audio output device.
  // 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.
  // TODO(olka): make sure callback is always called on the client thread,
  // update clients accordingly and fix the comment.
  virtual void SwitchOutputDevice(
      const std::string& device_id,
      const url::Origin& security_origin,
      const media::OutputDeviceStatusCB& callback) = 0;

  // Time stamp that reflects the current render time. Should not be updated
  // when paused.
  virtual base::TimeDelta GetCurrentRenderTime() const = 0;

  // Returns true if the implementation is a local renderer and false
  // otherwise.
  virtual bool IsLocalRenderer() const = 0;

 protected:
  friend class base::RefCountedThreadSafe<MediaStreamAudioRenderer>;

  virtual ~MediaStreamAudioRenderer() {}
};

}  // namespace content

#endif  // CONTENT_PUBLIC_RENDERER_MEDIA_STREAM_AUDIO_RENDERER_H_