2557b86e76
The main purpose was the interface-> include rename, but other files were also moved, eliminating the "main" dir. To avoid breaking downstream, the "interface" directories were copied into a new "video_coding/include" dir. The old headers got pragma warnings added about deprecation (a very short deprecation since I plan to remove them as soon downstream is updated). Other files also moved: video_coding/main/source -> video_coding video_coding/main/test -> video_coding/test BUG=webrtc:5095 TESTED=Passing compile-trybots with --clobber flag: git cl try --clobber --bot=win_compile_rel --bot=linux_compile_rel --bot=android_compile_rel --bot=mac_compile_rel --bot=ios_rel --bot=linux_gn_rel --bot=win_x64_gn_rel --bot=mac_x64_gn_rel --bot=android_gn_rel -m tryserver.webrtc R=stefan@webrtc.org, tommi@webrtc.org Review URL: https://codereview.webrtc.org/1417283007 . Cr-Commit-Position: refs/heads/master@{#10694}
115 lines
3.6 KiB
C++
115 lines
3.6 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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{
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Reset(currentWallClock);
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}
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// Resets the delay estimate
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void
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VCMInterFrameDelay::Reset(int64_t currentWallClock)
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{
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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
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VCMInterFrameDelay::CalculateDelay(uint32_t timestamp,
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int64_t *delay,
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int64_t currentWallClock)
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{
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if (_prevWallClock == 0)
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{
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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) || wrapAroundsSincePrev < 0)
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{
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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>((timestamp + wrapAroundsSincePrev *
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(static_cast<int64_t>(1)<<32) - _prevTimestamp) / 90.0 + 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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{
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if (_dTS < 0)
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{
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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 and
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// keeps track of the number of wrap arounds since reset.
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void
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VCMInterFrameDelay::CheckForWrapArounds(uint32_t timestamp)
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{
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if (timestamp < _prevTimestamp)
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{
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// This difference will probably be less than -2^31 if we have had a wrap around
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// (e.g. timestamp = 1, _previousTimestamp = 2^32 - 1). Since it is cast to 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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{
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// Forward wrap around
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_wrapArounds++;
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}
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}
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// This difference will probably be less than -2^31 if we have had a backward 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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{
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// Backward wrap around
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_wrapArounds--;
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}
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}
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}
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