4 Videos at same time


We are trying to play 4x 1080 videos at the same time with a blackmagic quad and tested several ways, but the videos get out of sync in some point.

We have tried with load and play and even in 4k grid.

We need to pause them and resume them again, so after some pauses and resumes it gets out of sync. Is there another way that we can sync the 4 videos?


Can you verify you are using the origional quad, not the quad 2? I will let the developers that know, answer with specifics, but that might make a difference.

We used the original quad for 4x independent videos and a 4k Extreme for 4k grid.


IIRC the play and pause commands will be executed synchronously, so they might fall into two frames.
The only way to prevent that is to have 4 channels, as each channel gets its own command queue, but even then there is some chance that they will fall into 2 frames based on when exactly they are being sent.

Another option would be to schedule the commands in advance using timecode, but that feature is currently not yet available in any official builds. (relevant issue is #872)

Would it be possible the render the 4 videos into a single 4k file?
You could then play that on a 4k channel running, and use the route command with mixer transforms to split it up to the 4 outputs. This way they may be a frame out all the time, but they will never drift any further apart.

The commands arent necessarily run synchronously, but there will be some unpredictable timing in the command execution for pause and resume, which makes using multiple files problematic

I’ve tried the 4K but after some pauses it gets out of sync. If you play it normally appears to be sync.
Going to test the solution with the time code.


I have used Julusian’s option a few times.
One thing is very important GENLOCK
and use the same framerate all the way.
i have the feel I-frame only video’s also narrows down faults.
It is not fault free but you can get close.

The new timecode feature is the promise for this setup :wink:

We used a Duo (2 channels) playing two videos for a show and after 3 minutes had 12 frames drift. Experimenting with a QUAD 2 for an E.P. project with stills (MJPEG) split and masked stayed in sync but only up to 30fps. I might be able to share the server code (Linux).

Thanks rcourtney, hope to see it.

Drifts often related to dropped- or late frames. Run with log level trace and monitor logs for those.

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I am certain you are correct on late frames. I added inline assember moves as a for/next loop is far too slow.

Anyone knows if it is possible now with version 2.2 of CasparCG?