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cscore: MjpegServer: Fix FPS limiting (#1536)

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This uses a 1-second window average to try to hit the desired FPS.
This commit is contained in:
Peter Johnson
2019-01-09 22:50:34 -08:00
committed by GitHub
parent 444b899a9f
commit f889b45d59
1 changed files with 24 additions and 7 deletions
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31
cscore/src/main/native/cpp/MjpegServerImpl.cpp
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@@ -643,8 +643,9 @@ void MjpegServerImpl::ConnThread::SendStream(wpi::raw_socket_ostream& os) {
Frame::Time lastFrameTime = 0;
Frame::Time timePerFrame = 0;
if (m_fps != 0) timePerFrame = 1000000.0 / m_fps;
// Allow fudge factor of 1 ms in frame rate
if (timePerFrame >= 1000) timePerFrame -= 1000;
Frame::Time averageFrameTime = 0;
Frame::Time averagePeriod = 1000000; // 1 second window
if (averagePeriod < timePerFrame) averagePeriod = timePerFrame * 10;
StartStream();
while (m_active && !os.has_error()) {
@@ -665,10 +666,26 @@ void MjpegServerImpl::ConnThread::SendStream(wpi::raw_socket_ostream& os) {
continue;
}
if (frame.GetTime() < (lastFrameTime + timePerFrame)) {
// Limit FPS; sleep for 10 ms so we don't consume all processor time
std::this_thread::sleep_for(std::chrono::milliseconds(10));
continue;
auto thisFrameTime = frame.GetTime();
if (thisFrameTime != 0 && timePerFrame != 0 && lastFrameTime != 0) {
Frame::Time deltaTime = thisFrameTime - lastFrameTime;
// drop frame if it is early compared to the desired frame rate AND
// the current average is higher than the desired average
if (deltaTime < timePerFrame && averageFrameTime < timePerFrame) {
// sleep for 1 ms so we don't consume all processor time
std::this_thread::sleep_for(std::chrono::milliseconds(1));
continue;
}
// update average
if (averageFrameTime != 0) {
averageFrameTime =
averageFrameTime * (averagePeriod - timePerFrame) / averagePeriod +
deltaTime * timePerFrame / averagePeriod;
} else {
averageFrameTime = deltaTime;
}
}
int width = m_width != 0 ? m_width : frame.GetOriginalWidth();
@@ -705,7 +722,7 @@ void MjpegServerImpl::ConnThread::SendStream(wpi::raw_socket_ostream& os) {
// print the individual mimetype and the length
// sending the content-length fixes random stream disruption observed
// with firefox
lastFrameTime = frame.GetTime();
lastFrameTime = thisFrameTime;
double timestamp = lastFrameTime / 1000000.0;
header.clear();
oss << "\r\n--" BOUNDARY "\r\n"