Cast: Basic cast_receiver API for chrome.

media/base/video_capturer_source.h

+// Copyright (c) 2015 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 MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURER_SOURCE_H_
+#define MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURER_SOURCE_H_
+
+#include <string>
+#include <vector>
+#include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+#include "base/single_thread_task_runner.h"
+#include "media/base/media_export.h"
+#include "media/base/video_capture_types.h"
+#include "media/base/video_frame.h"
+
+namespace media {
+
+// VideoCapturerSource is an interface representing the source for
+// captured video.  An implementation will periodically call the frame
+// callback with new video frames.
+class MEDIA_EXPORT VideoCapturerSource
+    : public base::RefCounted<media::VideoCapturerSource> {
+ public:
+  // 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)>
+      VideoCaptureDeliverFrameCB;
+
+  typedef base::Callback<void(const media::VideoCaptureFormats&)>
+      VideoCaptureDeviceFormatsCB;
+
+  typedef base::Callback<void(bool)> RunningCallback;
+
+  // Collects the formats that can currently be used.
+  // |max_requested_height|, |max_requested_width|, and
+  // |max_requested_frame_rate| is used by Tab and Screen capture to decide what
+  // resolution/framerate to generate. |callback| is triggered when the formats
+  // have been collected.
+  virtual void GetCurrentSupportedFormats(
+      int max_requested_width,
+      int max_requested_height,
+      double max_requested_frame_rate,
+      const VideoCaptureDeviceFormatsCB& callback) = 0;
+
+  // Starts capturing frames using the resolution in |params|.
+  // |new_frame_callback| is triggered on |frame_callback_task_runner|
+  // when a new video frame is available.
+  // If capturing is started successfully then |running_callback| will be
+  // called with a parameter of true. Note that some implementations may
+  // simply reject StartCapture (by calling running_callback with a false
+  // argument) if called with the wrong task runner.
+  // If capturing fails to start or stopped due to an external event then
+  // |running_callback| will be called with a parameter of false.
+  // |running_callback| will always be called on the same thread as the
+  // StartCapture.
+  virtual void StartCapture(
+      const media::VideoCaptureParams& params,
+      const VideoCaptureDeliverFrameCB& new_frame_callback,
+      scoped_refptr<base::SingleThreadTaskRunner> frame_callback_task_runner,
+      const RunningCallback& running_callback) = 0;
+
+  // Stops capturing frames and clears all callbacks including the
+  // SupportedFormatsCallback callback. Note that queued frame callbacks
+  // may still occur after this call, so the caller must take care to
+  // use refcounted or weak references in |new_frame_callback|.
+  virtual void StopCapture() = 0;
+
+ protected:
+  friend class base::RefCounted<VideoCapturerSource>;
+  virtual ~VideoCapturerSource();
+};
+
+}  // namespace media
+
+#endif  // MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURER_SOURCE_H_