modules/video_coding/inter_frame_delay.h

/*
 *  Copyright (c) 2011 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_MODULES_VIDEO_CODING_INTER_FRAME_DELAY_H_
#define WEBRTC_MODULES_VIDEO_CODING_INTER_FRAME_DELAY_H_

#include "webrtc/typedefs.h"

namespace webrtc {

class VCMInterFrameDelay {
 public:
  explicit VCMInterFrameDelay(int64_t currentWallClock);

  // Resets the estimate. Zeros are given as parameters.
  void Reset(int64_t currentWallClock);

  // Calculates the delay of a frame with the given timestamp.
  // This method is called when the frame is complete.
  //
  // Input:
  //          - timestamp         : RTP timestamp of a received frame
  //          - *delay            : Pointer to memory where the result should be
  //          stored
  //          - currentWallClock  : The current time in milliseconds.
  //                                Should be -1 for normal operation, only used
  //                                for testing.
  // Return value                 : true if OK, false when reordered timestamps
  bool CalculateDelay(uint32_t timestamp,
                      int64_t* delay,
                      int64_t currentWallClock);

  // Returns the current difference between incoming timestamps
  //
  // Return value                 : Wrap-around compensated difference between
  // incoming
  //                                timestamps.
  uint32_t CurrentTimeStampDiffMs() const;

 private:
  // Controls if the RTP timestamp counter has had a wrap around
  // between the current and the previously received frame.
  //
  // Input:
  //          - timestmap         : RTP timestamp of the current frame.
  void CheckForWrapArounds(uint32_t timestamp);

  int64_t _zeroWallClock;  // Local timestamp of the first video packet received
  int32_t _wrapArounds;    // Number of wrapArounds detected
  // The previous timestamp passed to the delay estimate
  uint32_t _prevTimestamp;
  // The previous wall clock timestamp used by the delay estimate
  int64_t _prevWallClock;
  // Wrap-around compensated difference between incoming timestamps
  int64_t _dTS;
};

}  // namespace webrtc

#endif  // WEBRTC_MODULES_VIDEO_CODING_INTER_FRAME_DELAY_H_