content/public/renderer/media_stream_audio_sink.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_PUBLIC_RENDERER_MEDIA_STREAM_AUDIO_SINK_H_
   6 #define CONTENT_PUBLIC_RENDERER_MEDIA_STREAM_AUDIO_SINK_H_
   7
   8 #include <vector>
   9
  10 #include "base/basictypes.h"
  11 #include "base/time/time.h"
  12 #include "content/common/content_export.h"
  13 #include "content/public/renderer/media_stream_sink.h"
  14
  15 namespace blink {
  16 class WebMediaStreamTrack;
  17 }
  18
  19 namespace media {
  20 class AudioBus;
  21 class AudioParameters;
  22 }
  23
  24 namespace content {
  25
  26 class CONTENT_EXPORT MediaStreamAudioSink : public MediaStreamSink {
  27  public:
  28   // Adds a MediaStreamAudioSink to the audio track to receive audio data from
  29   // the track.
  30   // Called on the main render thread.
  31   static void AddToAudioTrack(MediaStreamAudioSink* sink,
  32                               const blink::WebMediaStreamTrack& track);
  33
  34   // Removes a MediaStreamAudioSink from the audio track to stop receiving
  35   // audio data from the track.
  36   // Called on the main render thread.
  37   static void RemoveFromAudioTrack(MediaStreamAudioSink* sink,
  38                                    const blink::WebMediaStreamTrack& track);
  39
  40   // Callback called to deliver audio data. The data in |audio_bus| respects the
  41   // AudioParameters passed in the last call to OnSetFormat().  Called on
  42   // real-time audio thread.
  43   //
  44   // |estimated_capture_time| is the local time at which the first sample frame
  45   // in |audio_bus| either: 1) was generated, if it was done so locally; or 2)
  46   // should be targeted for play-out, if it was generated from a remote
  47   // source. Either way, an implementation should not play-out the audio before
  48   // this point-in-time. This value is NOT a high-resolution timestamp, and so
  49   // it should not be used as a presentation time; but, instead, it should be
  50   // used for buffering playback and for A/V synchronization purposes.
  51   virtual void OnData(const media::AudioBus& audio_bus,
  52                       base::TimeTicks estimated_capture_time) = 0;
  53
  54   // Callback called when the format of the audio stream has changed.  This is
  55   // always called at least once before OnData(), and on the same thread.
  56   virtual void OnSetFormat(const media::AudioParameters& params) = 0;
  57
  58  protected:
  59   ~MediaStreamAudioSink() override {}
  60 };
  61
  62 }  // namespace content
  63
  64 #endif  // CONTENT_PUBLIC_RENDERER_MEDIA_STREAM_AUDIO_SINK_H_