content/public/renderer/media_stream_video_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_VIDEO_SINK_H_
   6 #define CONTENT_PUBLIC_RENDERER_MEDIA_STREAM_VIDEO_SINK_H_
   7
   8 #include "base/callback.h"
   9 #include "base/compiler_specific.h"
  10 #include "base/memory/ref_counted.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 media {
  16 class VideoCaptureFormat;
  17 class VideoFrame;
  18 }
  19
  20 namespace blink {
  21 class WebMediaStreamTrack;
  22 }
  23
  24 namespace content {
  25
  26 // This callback is used to deliver video frames.
  27 // |estimated_capture_time| - An optional field to provide the capture time of
  28 // the delivered video frame. This field usually means the local time when the
  29 // video frame was generated. It is possible for this value to be null if this
  30 // timing information cannot be determined. There is no gurantee that this
  31 // value is accurate. For example video frames from a remote source can only
  32 // provide this timing information as an estimate.
  33 // |video_frame->timestamp()| gives the presentation timestamp of the video
  34 // frame relative to the first frame generated by the corresponding source.
  35 // Because a source can start generating frames before a subscriber is added,
  36 // the first video frame delivered may not have timestamp equal to 0.
  37 typedef base::Callback<
  38   void(const scoped_refptr<media::VideoFrame>& video_frame,
  39        const media::VideoCaptureFormat& format,
  40        const base::TimeTicks& estimated_capture_time)>
  41     VideoCaptureDeliverFrameCB;
  42
  43 // MediaStreamVideoSink is an interface used for receiving video frames from a
  44 // Video Stream Track or a Video Source.
  45 // http://dev.w3.org/2011/webrtc/editor/getusermedia.html
  46 // All methods calls will be done from the main render thread.
  47 class CONTENT_EXPORT MediaStreamVideoSink : public MediaStreamSink {
  48  public:
  49   // An implementation of MediaStreamVideoSink should call AddToVideoTrack when
  50   // it is ready to receive data from a video track. Before the implementation
  51   // is destroyed, RemoveFromVideoTrack must be called.
  52   //
  53   // Calls to these methods must be done on the main render thread.
  54   // Note that |callback| for frame delivery happens on the IO thread.
  55   //
  56   // Calling RemoveFromVideoTrack also not stop frame delivery through the
  57   // callback immediately because it may happen on another thread.
  58   // The added callback will be reset on the render thread.
  59   static void AddToVideoTrack(MediaStreamVideoSink* sink,
  60                               const VideoCaptureDeliverFrameCB& callback,
  61                               const blink::WebMediaStreamTrack& track);
  62   static void RemoveFromVideoTrack(MediaStreamVideoSink* sink,
  63                                    const blink::WebMediaStreamTrack& track);
  64
  65  protected:
  66   virtual ~MediaStreamVideoSink() {}
  67 };
  68
  69
  70 }  // namespace content
  71
  72 #endif  // CONTENT_PUBLIC_RENDERER_MEDIA_STREAM_VIDEO_SINK_H_