content/browser/renderer_host/media/web_contents_audio_input_stream.h

// Copyright (c) 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.
//
// An AudioInputStream which provides a loop-back of all audio output generated
// by the RenderView associated with a WebContents instance.  The single stream
// of data is produced by format-converting and mixing all audio output from a
// RenderView.  In other words, WebContentsAudioInputStream provides tab-level
// audio mirroring.
//
// The implementation observes a WebContents instance (which represents a
// browser tab) so that it can track the replacement of RenderViews due to
// navigation, crash/reload, etc. events; and take appropriate actions to
// provide a seamless, uninterrupted mirroring experience.

#ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_WEB_CONTENTS_AUDIO_INPUT_STREAM_H_
#define CONTENT_BROWSER_RENDERER_HOST_MEDIA_WEB_CONTENTS_AUDIO_INPUT_STREAM_H_

#include <string>

#include "base/memory/ref_counted.h"
#include "content/common/content_export.h"
#include "media/audio/audio_io.h"

namespace base {
class MessageLoopProxy;
}

namespace media {
class AudioParameters;
class VirtualAudioInputStream;
}

namespace content {

class AudioMirroringManager;
class WebContentsTracker;

class CONTENT_EXPORT WebContentsAudioInputStream
    : NON_EXPORTED_BASE(public media::AudioInputStream) {
 public:
  // media::AudioInputStream implementation
  virtual bool Open() OVERRIDE;
  virtual void Start(AudioInputCallback* callback) OVERRIDE;
  virtual void Stop() OVERRIDE;
  virtual void Close() OVERRIDE;
  virtual double GetMaxVolume() OVERRIDE;
  virtual void SetVolume(double volume) OVERRIDE;
  virtual double GetVolume() OVERRIDE;
  virtual void SetAutomaticGainControl(bool enabled) OVERRIDE;
  virtual bool GetAutomaticGainControl() OVERRIDE;

  // Create a new audio mirroring session, or return NULL on error.  |device_id|
  // should be in the format accepted by
  // WebContentsCaptureUtil::ExtractTabCaptureTarget().  The caller must
  // guarantee Close() is called on the returned object so that it may
  // self-destruct.
  // |worker_loop| is the loop on which AudioInputCallback methods are called
  // and may or may not be the single thread that invokes the AudioInputStream
  // methods.
  static WebContentsAudioInputStream* Create(
      const std::string& device_id,
      const media::AudioParameters& params,
      const scoped_refptr<base::MessageLoopProxy>& worker_loop,
      AudioMirroringManager* audio_mirroring_manager);

 private:
  friend class WebContentsAudioInputStreamTest;

  // Maintain most state and functionality in an internal ref-counted
  // implementation class.  This object must outlive a call to Close(), until
  // the shutdown tasks running on other threads complete: The
  // AudioMirroringManager on the IO thread, the WebContentsTracker on the UI
  // thread, and the VirtualAudioOuputStreams on the audio thread.
  class Impl;

  WebContentsAudioInputStream(
      int render_process_id, int render_view_id,
      AudioMirroringManager* mirroring_manager,
      const scoped_refptr<WebContentsTracker>& tracker,
      media::VirtualAudioInputStream* mixer_stream);

  virtual ~WebContentsAudioInputStream();

  scoped_refptr<Impl> impl_;

  DISALLOW_COPY_AND_ASSIGN(WebContentsAudioInputStream);
};

}  // namespace content

#endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_WEB_CONTENTS_AUDIO_INPUT_STREAM_H_