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// 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.
#include "base/callback.h"
#include "base/compiler_specific.h"
#include "base/memory/ref_counted.h"
#include "base/time/time.h"
#include "content/common/content_export.h"
#include "content/public/renderer/media_stream_sink.h"
namespace media {
class VideoCaptureFormat;
class VideoFrame;
namespace blink {
class WebMediaStreamTrack;
namespace content {
// This callback is used to deliver video frames.
// |estimated_capture_time| - The capture time of the delivered video
// frame. This field represents the local time at which either: 1) the frame was
// generated, if it was done so locally; or 2) the targeted play-out time of the
// frame, if it was generated from a remote source. Either way, an
// implementation should not present the frame before this point-in-time. This
// value is NOT a high-resolution timestamp, and so it should not be used as a
// presentation time; but, instead, it should be used for buffering playback and
// for A/V synchronization purposes. NOTE: It is possible for this value to be
// null if the current implementation lacks this timing information.
// |video_frame->timestamp()| gives the presentation timestamp of the video
// frame relative to the first frame generated by the corresponding source.
// Because a source can start generating frames before a subscriber is added,
// the first video frame delivered may not have timestamp equal to 0.
typedef base::Callback<
void(const scoped_refptr<media::VideoFrame>& video_frame,
const media::VideoCaptureFormat& format,
const base::TimeTicks& estimated_capture_time)>
// MediaStreamVideoSink is an interface used for receiving video frames from a
// Video Stream Track or a Video Source.
// All methods calls will be done from the main render thread.
class CONTENT_EXPORT MediaStreamVideoSink : public MediaStreamSink {
// An implementation of MediaStreamVideoSink should call AddToVideoTrack when
// it is ready to receive data from a video track. Before the implementation
// is destroyed, RemoveFromVideoTrack must be called.
// Calls to these methods must be done on the main render thread.
// Note that |callback| for frame delivery happens on the IO thread.
// Calling RemoveFromVideoTrack also not stop frame delivery through the
// callback immediately because it may happen on another thread.
// The added callback will be reset on the render thread.
static void AddToVideoTrack(MediaStreamVideoSink* sink,
const VideoCaptureDeliverFrameCB& callback,
const blink::WebMediaStreamTrack& track);
static void RemoveFromVideoTrack(MediaStreamVideoSink* sink,
const blink::WebMediaStreamTrack& track);
~MediaStreamVideoSink() override {}
} // namespace content