89 lines
2.7 KiB
C++
89 lines
2.7 KiB
C++
/*
|
|
* Copyright 2021 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 "common_video/framerate_controller.h"
|
|
|
|
#include <limits>
|
|
|
|
#include "rtc_base/time_utils.h"
|
|
|
|
namespace webrtc {
|
|
namespace {
|
|
constexpr double kMinFramerate = 0.5;
|
|
} // namespace
|
|
|
|
FramerateController::FramerateController()
|
|
: FramerateController(std::numeric_limits<double>::max()) {}
|
|
|
|
FramerateController::FramerateController(double max_framerate)
|
|
: max_framerate_(max_framerate) {}
|
|
|
|
FramerateController::~FramerateController() {}
|
|
|
|
void FramerateController::SetMaxFramerate(double max_framerate) {
|
|
max_framerate_ = max_framerate;
|
|
}
|
|
|
|
double FramerateController::GetMaxFramerate() const {
|
|
return max_framerate_;
|
|
}
|
|
|
|
bool FramerateController::ShouldDropFrame(int64_t in_timestamp_ns) {
|
|
if (max_framerate_ < kMinFramerate)
|
|
return true;
|
|
|
|
// If `max_framerate_` is not set (i.e. maxdouble), `frame_interval_ns` is
|
|
// rounded to 0.
|
|
int64_t frame_interval_ns = rtc::kNumNanosecsPerSec / max_framerate_;
|
|
if (frame_interval_ns <= 0) {
|
|
// Frame rate throttling not enabled.
|
|
return false;
|
|
}
|
|
|
|
if (next_frame_timestamp_ns_) {
|
|
// Time until next frame should be outputted.
|
|
const int64_t time_until_next_frame_ns =
|
|
(*next_frame_timestamp_ns_ - in_timestamp_ns);
|
|
// Continue if timestamp is within expected range.
|
|
if (std::abs(time_until_next_frame_ns) < 2 * frame_interval_ns) {
|
|
// Drop if a frame shouldn't be outputted yet.
|
|
if (time_until_next_frame_ns > 0)
|
|
return true;
|
|
// Time to output new frame.
|
|
*next_frame_timestamp_ns_ += frame_interval_ns;
|
|
return false;
|
|
}
|
|
}
|
|
|
|
// First timestamp received or timestamp is way outside expected range, so
|
|
// reset. Set first timestamp target to just half the interval to prefer
|
|
// keeping frames in case of jitter.
|
|
next_frame_timestamp_ns_ = in_timestamp_ns + frame_interval_ns / 2;
|
|
return false;
|
|
}
|
|
|
|
void FramerateController::Reset() {
|
|
max_framerate_ = std::numeric_limits<double>::max();
|
|
next_frame_timestamp_ns_ = absl::nullopt;
|
|
}
|
|
|
|
void FramerateController::KeepFrame(int64_t in_timestamp_ns) {
|
|
if (ShouldDropFrame(in_timestamp_ns)) {
|
|
if (max_framerate_ < kMinFramerate)
|
|
return;
|
|
|
|
int64_t frame_interval_ns = rtc::kNumNanosecsPerSec / max_framerate_;
|
|
if (next_frame_timestamp_ns_)
|
|
*next_frame_timestamp_ns_ += frame_interval_ns;
|
|
}
|
|
}
|
|
|
|
} // namespace webrtc
|