Audio not synced correctly with video

[ksp54]

Hello! This is my first post and I'm very new to this.

I imported a .mov file that I created to DCP-o-matic, but when I play the video in DCP-o-matic, the audio is out of sync....

Hi,
in my case I'm optimistic that its working now.
I did as follows:
- installed ffmpeg.exe on my windows 64 computer
- extracted 1min from the overall movie to make experimenting easier FFMPEG -ss 00:10:00 - input.mov -t 00:01:00 -c copy output.mov
- converted the file from .mov to .mp4: FFMPEG -i input.mov -vf "fps=24, format=yuv420p" -c:v libx264 -preset fast -crf 23 -c:a aac -af "aresample=async=1" -b:a 256k output.mp4

I've used ChatGPT to get this cmd line arguments. the tool suggested e.g. "fps=24, format=yuv420p" because it seems to work well witch APPLE ProRes encoders which is the case in my file. The format format=yuv420p is called Frame-Blending. It makes the movie run smoother. The option -af "aresample=async=1" is to align audio with video.

After having the movie converted to MP4 with 24fps, dcp-o-matic works nicely for my 1min sample.
Now I'm looking forward to tomorrow morning if the complete result even works. Takes 9h to convert the whole movie.
Next Thursday we have the option to test the dcp package in a real cinema in Dortmund, Germany . Its a fairly small cinema but the owner is really nice and smart allowing us to use his equipment. lets see what happens...

[carl]

I would be interested to get a copy of your "input.mov" (the short segment) if that's at all possible.

[hoost]

Thanks so much for looking into this, Carl! Sorry, I was away on vacation for a few days, so I'm just getting back to this.

Yes, you're totally right. The DCP I sent you actually included the 370ms delay, so an additional 370ms would actually put us at a 740ms delay. I created a new DCP without the delay, and everything seems to be fine. Plays back perfectly in DCP-o-matic. I'm not sure why everything seemed so off in the DCP player in DCP-o-matic when I first tried creating the DCP file, but everything seems fine now. Thank you very much for looking into this!

[carl]

I'm glad it's working now!