Implement timestamp translation/filter in VideoCapturer.

webrtc/media/base/videoframefactory.h

 /*
  *  Copyright (c) 2014 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_VIDEOFRAMEFACTORY_H_
 #define WEBRTC_MEDIA_BASE_VIDEOFRAMEFACTORY_H_
 
 #include <memory>
 
 #include "webrtc/common_video/include/i420_buffer_pool.h"
 #include "webrtc/media/base/videoframe.h"
 
 namespace cricket {
 
 struct CapturedFrame;
 class VideoFrame;
 
 // Creates cricket::VideoFrames, or a subclass of cricket::VideoFrame
 // depending on the subclass of VideoFrameFactory.
 class VideoFrameFactory {
  public:
-  VideoFrameFactory() : apply_rotation_(false) {}
+  VideoFrameFactory() : apply_rotation_(false), timestamp_offset_us_(0) {}
   virtual ~VideoFrameFactory() {}
 
   // The returned frame aliases the aliased_frame if the input color
   // space allows for aliasing, otherwise a color conversion will
   // occur. Returns NULL if conversion fails.
 
   // The returned frame will be a center crop of |input_frame| with
   // size |cropped_width| x |cropped_height|.
   virtual VideoFrame* CreateAliasedFrame(const CapturedFrame* input_frame,
                                          int cropped_width,
                                          int cropped_height) const = 0;
 
   // The returned frame will be a center crop of |input_frame| with size
   // |cropped_width| x |cropped_height|, scaled to |output_width| x
   // |output_height|.
   virtual VideoFrame* CreateAliasedFrame(const CapturedFrame* input_frame,
                                          int cropped_input_width,
                                          int cropped_input_height,
                                          int output_width,
                                          int output_height) const;
 
   void SetApplyRotation(bool enable) { apply_rotation_ = enable; }
+  // TODO(nisse): Delete this method? Not much use in extending this
+  // class, which we'de like to delete.
+  void SetTimestampOffset(int64_t offset) { timestamp_offset_us_ = offset; }
 
  protected:
   bool apply_rotation_;
+  // Offset added to the capture timestamp, to translate it to the
+  // system monotonic time attached to the produced VideoFrame.
+  int64_t timestamp_offset_us_;
 
  private:
   // An internal pool to avoid reallocations. It is mutable because it
   // does not affect behaviour, only performance.
   mutable webrtc::I420BufferPool pool_;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_MEDIA_BASE_VIDEOFRAMEFACTORY_H_