View Full Version : How to know if captured frame is valid

January 16, 2004, 01:08:50
I am using the continuous capture mode on the Imaging Source FireWire framegrabber to capture a stream of frames. Sometimes I notice that when I start the capture, the first one to three frames or so show the blue background with "NO VIDEO", and then I get the frames from the camera as expected.

Is there a way to know that I am getting "good" frames from the camera?

Stefan Geissler
January 16, 2004, 07:46:25

At this point of time, there is flag to indicate, whether a frame is ready or not.
I use for testing whether a frame is valid, the colors of the first few pixels. If they all are blue (RGB 0,0,255) (if you set an RGB video format), then it is improbable that the frame is valid. If you convert from a YUV format, the value for blue differs from the blue value of an RGB video format. This depends on the YUV->RGB transform filter.
If the frame is valid, it is very improbable that a few pixels in one line show the same blue color values because of the normal noise of the camera.

January 16, 2004, 20:04:37
OK, that's the approach I am taking as well. Thanks for the info!