I'm trying to capture video from a webcam, and I find that when I use the -vcodec copy option, it works really well (far better than any other software I've tried). However, I'd like my files to be a bit smaller, and it seems that every attempt I make to compress the video leads to extremely jumpy video. If, for example, I switch the output vcodec to mjpeg, it changes from reporting 15 fps to reporting between 3 and 4 fps. Am I doing something wrong?? Here is the call with -vcodec copy:
ffmpeg -y -f dshow -vcodec mjpeg -s 1184x656 -framerate 25 -i video="HD 720P Webcam" -vcodec copy test.avi
-- which gets me 15 fps. But if I change to mjpeg, I get only 3-4 fps:
ffmpeg -y -f dshow -vcodec mjpeg -s 1184x656 -framerate 25 -i video="HD 720P Webcam" -vcodec mjpeg test.avi
Experimental attempts to put -framerate 25 or -r 25 before test.avi also does nothing to help the situation. I'm not getting any smoother video when experimenting with mpeg4 or libx264 either. Only the copy option gives me smooth video (btw I'm filming my hands playing a piano, so there is a lot of fast motion in the videos).
Help!!!! And thank you...
I don't understand why the framerate drops so much, but you could try a 2 pass approach where you first record it using -vcodec copy (as you pasted in the question)
ffmpeg -y -f dshow -vcodec mjpeg -s 1184x656 -framerate 25 -i video="HD 720P Webcam" -vcodec copy test.avi
Then transcode it into mjpeg once it's done (something like this):
ffmpeg -i test.avi -vcodec mjpeg test.mjpeg
note: I haven't actually tested any of the above command lines.