9d3ab61325
Trying to submit all changes at once proved impossible since there were too many changes in too many files. The changes to PRESUBMIT.py will be uploaded in the last CL. (original CL: https://codereview.webrtc.org/1528503003/) BUG=webrtc:5309 TBR=mflodman@webrtc.org Review URL: https://codereview.webrtc.org/1543503002 Cr-Commit-Position: refs/heads/master@{#11102}
108 lines
3.5 KiB
C++
108 lines
3.5 KiB
C++
/*
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* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "webrtc/modules/video_coding/inter_frame_delay.h"
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namespace webrtc {
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VCMInterFrameDelay::VCMInterFrameDelay(int64_t currentWallClock) {
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Reset(currentWallClock);
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}
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// Resets the delay estimate
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void VCMInterFrameDelay::Reset(int64_t currentWallClock) {
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_zeroWallClock = currentWallClock;
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_wrapArounds = 0;
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_prevWallClock = 0;
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_prevTimestamp = 0;
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_dTS = 0;
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}
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// Calculates the delay of a frame with the given timestamp.
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// This method is called when the frame is complete.
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bool VCMInterFrameDelay::CalculateDelay(uint32_t timestamp,
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int64_t* delay,
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int64_t currentWallClock) {
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if (_prevWallClock == 0) {
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// First set of data, initialization, wait for next frame
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_prevWallClock = currentWallClock;
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_prevTimestamp = timestamp;
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*delay = 0;
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return true;
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}
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int32_t prevWrapArounds = _wrapArounds;
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CheckForWrapArounds(timestamp);
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// This will be -1 for backward wrap arounds and +1 for forward wrap arounds
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int32_t wrapAroundsSincePrev = _wrapArounds - prevWrapArounds;
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// Account for reordering in jitter variance estimate in the future?
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// Note that this also captures incomplete frames which are grabbed
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// for decoding after a later frame has been complete, i.e. real
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// packet losses.
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if ((wrapAroundsSincePrev == 0 && timestamp < _prevTimestamp) ||
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wrapAroundsSincePrev < 0) {
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*delay = 0;
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return false;
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}
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// Compute the compensated timestamp difference and convert it to ms and
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// round it to closest integer.
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_dTS = static_cast<int64_t>(
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(timestamp + wrapAroundsSincePrev * (static_cast<int64_t>(1) << 32) -
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_prevTimestamp) /
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90.0 +
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0.5);
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// frameDelay is the difference of dT and dTS -- i.e. the difference of
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// the wall clock time difference and the timestamp difference between
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// two following frames.
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*delay = static_cast<int64_t>(currentWallClock - _prevWallClock - _dTS);
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_prevTimestamp = timestamp;
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_prevWallClock = currentWallClock;
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return true;
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}
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// Returns the current difference between incoming timestamps
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uint32_t VCMInterFrameDelay::CurrentTimeStampDiffMs() const {
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if (_dTS < 0) {
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return 0;
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}
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return static_cast<uint32_t>(_dTS);
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}
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// Investigates if the timestamp clock has overflowed since the last timestamp
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// and
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// keeps track of the number of wrap arounds since reset.
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void VCMInterFrameDelay::CheckForWrapArounds(uint32_t timestamp) {
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if (timestamp < _prevTimestamp) {
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// This difference will probably be less than -2^31 if we have had a wrap
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// around
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// (e.g. timestamp = 1, _previousTimestamp = 2^32 - 1). Since it is cast to
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// a Word32,
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// it should be positive.
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if (static_cast<int32_t>(timestamp - _prevTimestamp) > 0) {
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// Forward wrap around
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_wrapArounds++;
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}
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// This difference will probably be less than -2^31 if we have had a
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// backward
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// wrap around.
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// Since it is cast to a Word32, it should be positive.
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} else if (static_cast<int32_t>(_prevTimestamp - timestamp) > 0) {
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// Backward wrap around
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_wrapArounds--;
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}
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}
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} // namespace webrtc
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