I am working on an application which requires video frame capture from different frame-grabber cards. I am using directshow ISampleGrabberCB::SampleCB callback to receive pointer to the new frame. Now I want to know when exactly this callback gets called ? Is it guaranteed that every time frame-grabber receives a new frame it will automatically get called ?
I was trying for 120Hz signals with various resolutions but I this callback is only getting called 50-55 times. So there is a possibility that my frame-grabber is not able to capture at that rate (although theoretically its capable). I want to find out whether this callback is bottleneck or framegrabber card.
Thank You
SampleCB is immediately called called from streaming thread, you have one call for every frame. While in callback, you block further streaming, that is you need to return control from your callback in order to resume (in particular, if your callback is "slow", it can reduce effective FPS).