public VideoFrame(Mat image, VideoFrameContext metadata)
{
Image = image;
Metadata = metadata;
}
private async Task StartCaptureAsync(TimeSpan publicationInterval, ChannelWriter <VideoFrame> writer, CancellationToken cancellationToken)
{
using var reader = this.InitCapture();
var width = reader.FrameWidth;
var height = reader.FrameHeight;
int frameCount = 0;
int delayMs = (int)(500.0 / this.Fps);
int errorCount = 0;
using Mat imageBuffer = new Mat();
Mat publishedImage;
var nextpublicationTime = DateTime.Now;
while (!cancellationToken.IsCancellationRequested && !_stopping)
{
var startTime = DateTime.Now;
// Grab single frame.
var timestamp = DateTime.Now;
bool success = reader.Read(imageBuffer);
frameCount++;
var endTime = DateTime.Now;
LogTrace("Producer: frame-grab took {0} ms", (endTime - startTime).Milliseconds);
if (!success || imageBuffer.Empty())
{
// If we've reached the end of the video, stop here.
if (IsContinuous)
{
errorCount++;
// If failed on live camera, try again.
_logger.LogWarning("Producer: null frame from live camera, continue! ({0} errors)", errorCount);
if (errorCount < 5)
{
_logger.LogWarning("Error in capture, retry");
continue;
}
else
{
_logger.LogWarning("Errorcount exceeded, restarting videocapture");
break;
}
}
else
{
_logger.LogWarning("Producer: null frame from video file, stop!");
_stopping = true;
// Break out of the loop to make sure we don't try grabbing more
// frames.
break;
}
}
else if (timestamp > nextpublicationTime)
{
LogTrace("Producer: create frame to publish:");
nextpublicationTime = timestamp + publicationInterval;
publishedImage = PreprocessImage(imageBuffer);
// Package the image for submission.
VideoFrameContext meta = new VideoFrameContext(timestamp, frameCount, this.Info);
VideoFrame vframe = new VideoFrame(publishedImage, meta);
LogTrace("Producer: do publishing");
var writeResult = writer.TryWrite(vframe);
}
//Thread.Sleep(delayMs);
await Task.Delay(delayMs, cancellationToken).ConfigureAwait(false);
}
}
