New class AdaptedVideoTrackSource.

webrtc/media/base/adaptedvideotracksource.h

+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_MEDIA_BASE_ADAPTEDVIDEOTRACKSOURCE_H_
+#define WEBRTC_MEDIA_BASE_ADAPTEDVIDEOTRACKSOURCE_H_
+
+#include "webrtc/api/mediastreaminterface.h"
+#include "webrtc/api/notifier.h"
+#include "webrtc/media/base/videoadapter.h"
+#include "webrtc/media/base/videobroadcaster.h"
+
+namespace rtc {
+
+class AdaptedVideoTrackSource

[perkj_webrtc, 2016/09/20 12:26:10]

Can you add a not about how this class should be used?
And please comment about that AdaptFrame and OnFrame is thread safe and can be
called on the camera thread.

[nisse-webrtc, 2016/09/20 13:17:47]

Done.

+    : public webrtc::Notifier<webrtc::VideoTrackSourceInterface> {
+ public:
+  AdaptedVideoTrackSource();
+
+  // Returns false if no stats are available, e.g, for a remote
+  // source, or a source which has not seen its first frame yet.
+  // Should avoid blocking.
+  bool GetStats(Stats* stats) override;

[perkj_webrtc, 2016/09/20 12:26:10]

All these methods should be made private. An implementation or a subclass should
not call these methods.

[nisse-webrtc, 2016/09/20 13:17:47]

Done. I'll never get used to this convention.

+
+  // Implements rtc::VideoSourceInterface
+  void AddOrUpdateSink(rtc::VideoSinkInterface<cricket::VideoFrame>* sink,
+                       const rtc::VideoSinkWants& wants) override;
+  void RemoveSink(rtc::VideoSinkInterface<cricket::VideoFrame>* sink) override;
+
+ protected:
+  // Checks the apply_rotation_ flag. If the frame needs rotation, it
+  // will be rotated if it is a plain memory frame, and discarded it
+  // if it is a native frame. (Subclasses producing native frames must
+  // handle applied_rotation themselves).
+  void OnFrame(const cricket::VideoFrame& frame);
+
+  void OnSinkWantsChanged(const rtc::VideoSinkWants& wants);

[perkj_webrtc, 2016/09/20 12:26:10]

private

[nisse-webrtc, 2016/09/20 13:17:47]

Done.

+
+  // Reports the appropriate frame size after adaptation. Returns true
+  // if a frame is wanted. Returns false if there are no interested
+  // sinks, or if the VideoAdapter decides to drop the frame.
+  bool AdaptFrame(int width,
+                  int height,
+                  int64_t time_us,
+                  int* out_width,
+                  int* out_height,
+                  int* crop_width,
+                  int* crop_height,
+                  int* crop_x,
+                  int* crop_y);
+
+  // Returns the current value of the apply_rotation flag, derived
+  // from the VideoSinkWants of registered sinks. Beware that when
+  // using this method, the value may become stale before it is used.

[perkj_webrtc, 2016/09/20 12:26:10]

mm-ok. the problem is not really appy_rotation()- the problem is that it should
be used on the same thread as where OnSinkWantsChanged is called. if not- is has
to be synchronized just the way you are.

Alternatively, you can have a virtual void OnApplyRotationChanged(bool
apply_rotation) = 0; method that the base class call when the flag is changed,
not sure if that is any better though.

+  bool apply_rotation();
+
+  cricket::VideoAdapter* video_adapter() { return &video_adapter_; }
+
+ private:
+  rtc::ThreadChecker thread_checker_;
+
+  cricket::VideoAdapter video_adapter_;
+
+  rtc::CriticalSection apply_rotation_crit_;
+  bool apply_rotation_ GUARDED_BY(apply_rotation_crit_);
+
+  rtc::CriticalSection stats_crit_;
+  rtc::Optional<Stats> stats_ GUARDED_BY(stats_crit_);
+
+  VideoBroadcaster broadcaster_;
+};
+
+}  // namespace rtc
+
+#endif  // WEBRTC_MEDIA_BASE_ADAPTEDVIDEOTRACKSOURCE_H_