Forum

Mjpeg keyframes

First (of probably many) questions…

I’ve recently got started with vvvv - and I’m trying to use it to develop a patch to playback videos, set cue points, create loops and reverse playback. I built a similar programme in Processing but found its performance lacking.

Currently I’m having issues getting videos to play backwards and all my reading points to not using the correct codec.

I have tried using ffmpeg to convert my .mov to an avi using the mjpeg codec, with keyframes at each frame but still I can’t get playback to run backwards when speed is -1.

I suspect that I’m not converting my video properly.

Can somebody please advise what ffmpeg command they use for video conversion to mjpeg with the correct keyframing?

I’m struggling to find clear advice on this online!

Up to now I haven’t seen a codec which supports reverse playback.
Do you need sound from the videos? If not your best option is to convert the videos to DDS sequences and use the Player node.

Yes sound would be needed, though the reverse playback feature is currently a ‘nice to have’.

Would another approach be to have two separate players for audio and video, and try to sync them up? Right now that is definitely beyond me but perhaps I will have a better grip on vvvv if I finish the other features first.

That said, mjpeg keyframing still seems important to achieve for video loops and cue points.

ok, you should have a look at these pages then:
https://discourse.vvvv.org/t/9738
faq codecs

we always recommend the commercial PICVIDEO mjpg codec since it compresses only keyframes and no diff frames which makes it possible to jump precisely to all frames… but there might be free alternatives.