/*
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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/base/checks.h"
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#include "webrtc/modules/video_processing/include/video_processing.h"
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#include "webrtc/modules/video_processing/video_decimator.h"
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#include "webrtc/system_wrappers/include/tick_util.h"
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#define VD_MIN(a, b) ((a) < (b)) ? (a) : (b)
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namespace webrtc {
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VPMVideoDecimator::VPMVideoDecimator() {
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Reset();
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}
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VPMVideoDecimator::~VPMVideoDecimator() {}
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void VPMVideoDecimator::Reset() {
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overshoot_modifier_ = 0;
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drop_count_ = 0;
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keep_count_ = 0;
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target_frame_rate_ = 30;
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incoming_frame_rate_ = 0.0f;
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memset(incoming_frame_times_, 0, sizeof(incoming_frame_times_));
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enable_temporal_decimation_ = true;
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}
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void VPMVideoDecimator::EnableTemporalDecimation(bool enable) {
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enable_temporal_decimation_ = enable;
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}
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void VPMVideoDecimator::SetTargetFramerate(int frame_rate) {
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RTC_DCHECK(frame_rate);
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target_frame_rate_ = frame_rate;
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}
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bool VPMVideoDecimator::DropFrame() {
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if (!enable_temporal_decimation_)
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return false;
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if (incoming_frame_rate_ <= 0)
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return false;
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const uint32_t incomingframe_rate =
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static_cast<uint32_t>(incoming_frame_rate_ + 0.5f);
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if (target_frame_rate_ == 0)
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return true;
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bool drop = false;
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if (incomingframe_rate > target_frame_rate_) {
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int32_t overshoot =
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overshoot_modifier_ + (incomingframe_rate - target_frame_rate_);
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if (overshoot < 0) {
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overshoot = 0;
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overshoot_modifier_ = 0;
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}
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if (overshoot && 2 * overshoot < (int32_t)incomingframe_rate) {
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if (drop_count_) { // Just got here so drop to be sure.
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drop_count_ = 0;
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return true;
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}
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const uint32_t dropVar = incomingframe_rate / overshoot;
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if (keep_count_ >= dropVar) {
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drop = true;
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overshoot_modifier_ = -((int32_t)incomingframe_rate % overshoot) / 3;
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keep_count_ = 1;
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} else {
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keep_count_++;
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}
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} else {
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keep_count_ = 0;
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const uint32_t dropVar = overshoot / target_frame_rate_;
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if (drop_count_ < dropVar) {
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drop = true;
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drop_count_++;
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} else {
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overshoot_modifier_ = overshoot % target_frame_rate_;
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drop = false;
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drop_count_ = 0;
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}
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}
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}
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return drop;
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}
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uint32_t VPMVideoDecimator::GetDecimatedFrameRate() {
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ProcessIncomingframe_rate(TickTime::MillisecondTimestamp());
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if (!enable_temporal_decimation_) {
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return static_cast<uint32_t>(incoming_frame_rate_ + 0.5f);
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}
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return VD_MIN(target_frame_rate_,
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static_cast<uint32_t>(incoming_frame_rate_ + 0.5f));
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}
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uint32_t VPMVideoDecimator::Inputframe_rate() {
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ProcessIncomingframe_rate(TickTime::MillisecondTimestamp());
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return static_cast<uint32_t>(incoming_frame_rate_ + 0.5f);
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}
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void VPMVideoDecimator::UpdateIncomingframe_rate() {
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int64_t now = TickTime::MillisecondTimestamp();
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if (incoming_frame_times_[0] == 0) {
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// First no shift.
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} else {
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// Shift.
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for (int i = kFrameCountHistory_size - 2; i >= 0; i--) {
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incoming_frame_times_[i + 1] = incoming_frame_times_[i];
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}
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}
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incoming_frame_times_[0] = now;
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ProcessIncomingframe_rate(now);
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}
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void VPMVideoDecimator::ProcessIncomingframe_rate(int64_t now) {
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int32_t num = 0;
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int32_t nrOfFrames = 0;
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for (num = 1; num < (kFrameCountHistory_size - 1); num++) {
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// Don't use data older than 2sec.
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if (incoming_frame_times_[num] <= 0 ||
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now - incoming_frame_times_[num] > kFrameHistoryWindowMs) {
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break;
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} else {
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nrOfFrames++;
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}
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}
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if (num > 1) {
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int64_t diff = now - incoming_frame_times_[num - 1];
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incoming_frame_rate_ = 1.0;
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if (diff > 0) {
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incoming_frame_rate_ = nrOfFrames * 1000.0f / static_cast<float>(diff);
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}
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} else {
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incoming_frame_rate_ = static_cast<float>(nrOfFrames);
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}
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}
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} // namespace webrtc
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