modules/video_coding refactorings

webrtc/modules/video_coding/main/source/inter_frame_delay.cc

-/*
- *  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.
- */
-
-#include "webrtc/modules/video_coding/main/source/inter_frame_delay.h"
-
-namespace webrtc {
-
-VCMInterFrameDelay::VCMInterFrameDelay(int64_t currentWallClock)
-{
-    Reset(currentWallClock);
-}
-
-// Resets the delay estimate
-void
-VCMInterFrameDelay::Reset(int64_t currentWallClock)
-{
-    _zeroWallClock = currentWallClock;
-    _wrapArounds = 0;
-    _prevWallClock = 0;
-    _prevTimestamp = 0;
-    _dTS = 0;
-}
-
-// Calculates the delay of a frame with the given timestamp.
-// This method is called when the frame is complete.
-bool
-VCMInterFrameDelay::CalculateDelay(uint32_t timestamp,
-                                int64_t *delay,
-                                int64_t currentWallClock)
-{
-    if (_prevWallClock == 0)
-    {
-        // First set of data, initialization, wait for next frame
-        _prevWallClock = currentWallClock;
-        _prevTimestamp = timestamp;
-        *delay = 0;
-        return true;
-    }
-
-    int32_t prevWrapArounds = _wrapArounds;
-    CheckForWrapArounds(timestamp);
-
-    // This will be -1 for backward wrap arounds and +1 for forward wrap arounds
-    int32_t wrapAroundsSincePrev = _wrapArounds - prevWrapArounds;
-
-    // Account for reordering in jitter variance estimate in the future?
-    // Note that this also captures incomplete frames which are grabbed
-    // for decoding after a later frame has been complete, i.e. real
-    // packet losses.
-    if ((wrapAroundsSincePrev == 0 && timestamp < _prevTimestamp) || wrapAroundsSincePrev < 0)
-    {
-        *delay = 0;
-        return false;
-    }
-
-    // Compute the compensated timestamp difference and convert it to ms and
-    // round it to closest integer.
-    _dTS = static_cast<int64_t>((timestamp + wrapAroundsSincePrev *
-                (static_cast<int64_t>(1)<<32) - _prevTimestamp) / 90.0 + 0.5);
-
-    // frameDelay is the difference of dT and dTS -- i.e. the difference of
-    // the wall clock time difference and the timestamp difference between
-    // two following frames.
-    *delay = static_cast<int64_t>(currentWallClock - _prevWallClock - _dTS);
-
-    _prevTimestamp = timestamp;
-    _prevWallClock = currentWallClock;
-
-    return true;
-}
-
-// Returns the current difference between incoming timestamps
-uint32_t VCMInterFrameDelay::CurrentTimeStampDiffMs() const
-{
-    if (_dTS < 0)
-    {
-        return 0;
-    }
-    return static_cast<uint32_t>(_dTS);
-}
-
-// Investigates if the timestamp clock has overflowed since the last timestamp and
-// keeps track of the number of wrap arounds since reset.
-void
-VCMInterFrameDelay::CheckForWrapArounds(uint32_t timestamp)
-{
-    if (timestamp < _prevTimestamp)
-    {
-        // This difference will probably be less than -2^31 if we have had a wrap around
-        // (e.g. timestamp = 1, _previousTimestamp = 2^32 - 1). Since it is cast to a Word32,
-        // it should be positive.
-        if (static_cast<int32_t>(timestamp - _prevTimestamp) > 0)
-        {
-            // Forward wrap around
-            _wrapArounds++;
-        }
-    }
-    // This difference will probably be less than -2^31 if we have had a backward wrap around.
-    // Since it is cast to a Word32, it should be positive.
-    else if (static_cast<int32_t>(_prevTimestamp - timestamp) > 0)
-    {
-        // Backward wrap around
-        _wrapArounds--;
-    }
-}
-
-}