Can I get compressed data from cvCapture, which is stored into buffer after cvGrabFrame, before using cvRetrieveFrame? I need to keep them in the an archive of compressed frames.
I use cvCaptureFromFile for getting rtsp stream from Axis IP camera.
As far as I see it it's not possible. CvCapture is a black box structure. There is not really a possibility to access the data inside.
There is the function cv::imencode to compress images. It is not optimal to compress the image again but it should work.
By the way, you're using the old C API and there is a newer API for C++ that makes capturing more elegant: cv::VideoCapture.