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