I know, that the issue had been widely discussed before, but after 5 hours of inefficient googling I guess I deserve to ask :) By the way, all such problems concerned earlier versions of OpenCV, so..
I've compiled fresh OpenCV 2.1. from source under Ubuntu 9.10. It works fine except of cvCreateVideoWriter, which returns null to the following request:
CvVideoWriter *writer = cvCreateVideoWriter("video.avi", CV_FOURCC('M','J','P','G'), fps, size, 0);
I've walked through the OpenCv folders - it even seems to have ffmpeg inside. I've also installed it on the system to make sure. I've changed CV_FOURCC('M','J','P','G') to -1 - all worthless.
I would appreciate your help soo much!
I recompiled OpenCV and ffmpeg from source again and it seems to work fine right now.