We have an application, where we get a message from an external system and then we take a picture, do some processing and return something back to the external system. Doing some performance testing, I found two problems (they are somewhat related). I was hoping someone will be able to explain this to me.
1) Does _capture.QueryFrame() buffer frames?
What we see is, if there is a gap between the query for two frames from a web camera, the second frame is often an older picture and not the one when the queryFrame was called.
We were able to mitigate this problem to some extent by discarding some frames, i.e. calling _capture.QueryFrame() 2-3 times and discarding the results.
2) The second issue is when we timed different parts of the application, we found that clearing the buffer (calling QueryFrame() 2-3 times and not using the results) takes about 65ms and then this line: Image<Bgr, Byte> source = _capture.QueryFrame() takes about 80ms. These two parts take the biggest chunk of processing time, our actual processing takes just about 20-30ms more.
Is there a faster way (a) to clear the buffer (b) to capture the frame?
If you have experience with OpenCV and know of something related, please do let me know.