Audio delay out on video

Anything and everything to do with DCP-o-matic.
Alta
Posts: 5
Joined: Fri Nov 01, 2019 12:04 am

Audio delay out on video

Post by Alta » Fri Nov 01, 2019 12:29 am

Hello,

I have some issue with my last DCP. For my cinema, i made a DCP but when i screened it entirely, I've seen that there is a delay between video and audio, increasing with time. At the end of the movie, the sync out is bigger. I have made another DCP and there is the same issue.

To make the DCP, I have used a Blu-ray video (the framerate is 23.976). I have add french subtitles on it that I have sync to the movie. When I read the video extract for the Blu-ray, on my player, all is OK. Not when I read the DCP. There is no sync out delay with the subtitles, only with the audio. It's difficult to tell exactly the audio delay, maybe 0''100 (1/10 secondes) at the end.

Am I doing something that create this delay when I made the DCP? Is the framerate (23.976) a problem? I can't find a solution.I have created for several years with DCP-o-matic, but I don't feel that I have already encountered this problem. Even thought I had a doubt recently (on spetember), with same issue about the delay on the DCP. But I didn't watch the entire movie.

If you could help me, I'd be more than happy to. And tell me if you want one file of the DCP.

Thank you

Nicolas

carl
Site Admin
Posts: 1082
Joined: Thu Nov 14, 2013 2:53 pm

Re: Audio delay out on video

Post by carl » Fri Nov 01, 2019 1:33 pm

Please can you send the metadata.xml and log files from inside your DCP-o-matic project folder to carl@dcpomatic.com

Carsten
Posts: 1462
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: Audio delay out on video

Post by Carsten » Fri Nov 01, 2019 1:43 pm

You may have fiddled with the frame rate settings in order to sync the subs. Usually, DCP-o-matic reads 23,98fps video and audio from bluray RIPs, and converts/references both to 24fps perfectly. Carl should be able to find out from your metadata file.

You could try to create a DCP from the Bluray Rip alone, leaving out the subtitles (create a new project for that). Check audio sync. Then add the subtitles to that DCP (as OV or as VF).

- Carsten

Alta
Posts: 5
Joined: Fri Nov 01, 2019 12:04 am

Re: Audio delay out on video

Post by Alta » Fri Nov 01, 2019 11:11 pm

Thank you.

I just sent both files to Carl.

Carsten, I'm going to do another DCP with the video (OV) and after made a VF with the French subtitles. Next week, I will then test the DCP in my cinema and see what happens. I'll tell you what happens after this test.

Nicolas

carl
Site Admin
Posts: 1082
Joined: Thu Nov 14, 2013 2:53 pm

Re: Audio delay out on video

Post by carl » Sat Nov 02, 2019 10:06 pm

Thanks for the files, Nico. I can't see anything in them that explains your problem.

Let us know how your new tests go (and keep the metadata.xml and log files around, if possible) then we can investigate.

Dindojul
Posts: 1
Joined: Wed Nov 23, 2016 11:49 am

Re: Audio delay out on video

Post by Dindojul » Tue Nov 05, 2019 10:13 am

I had a weird delay too... for the first time since long time I used DCP-o-matic.

It's for the season teaser of my theater, I have a mp4 file that I transform into a DCP, usually without any trouble.
This time, a very little out of synch betwwen audio and video, fast a second at the end.

My file is a mp4 1920x1080 25f/s, with AVC High@L4.0 for the video and AAC LC stereo for the audio.
I convert it in ProRes to see if it change something... and I'll try tomorrow.

I use DCP-o-matic 2.14.13.

Naturally, I have some short films to convert...
Is it better to leave the framerate as automatic (and make a non 24f/s DCP that "some projector may not be able to read") or force it to 24f/s?

Sincerely,

julien Favier

carl
Site Admin
Posts: 1082
Joined: Thu Nov 14, 2013 2:53 pm

Re: Audio delay out on video

Post by carl » Tue Nov 05, 2019 1:19 pm

@dindojul are you able to send me your mp4?

Alta
Posts: 5
Joined: Fri Nov 01, 2019 12:04 am

Re: Audio delay out on video

Post by Alta » Thu Nov 07, 2019 2:29 pm

Hi Carl & Carsten. And hello from France :)

Today, I tested the new DCP that I have made for my cinema. That's strange, because I have the same issue, a delay between the sound and the video, visible at the end of the movie. This is the same delay that I have encountered on the first DCP I have made for the last week's screening. One thing, I haven't add any subtitle on this new DCP this time.

I looked again at the video file that I use as a basis, and there is no such delay.

That's strange because I've just make another DCP (with French subtitles) for another movie that we screen today, and when I check it, I haven't seen any trouble on it. But I haven't see it entirely (I checked the beginning, the middle, and the end of the DCP).

I can send the metadata and other files from the DCP.

I can't understand why I have this problem.

Thanks,

Nico

Carsten
Posts: 1462
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: Audio delay out on video

Post by Carsten » Thu Nov 07, 2019 3:43 pm

What data rate have you chosen for this DCP?


At least in 2.14.11, I know that there is no principal bug, as I created a 95min DCP just a few days ago which showed no sync issues throughout.


Weird...

Please report your versions and upload your metadata.xml file here.

- Carsten

Alta
Posts: 5
Joined: Fri Nov 01, 2019 12:04 am

Re: Audio delay out on video

Post by Alta » Thu Nov 07, 2019 6:59 pm

Yes, the 2.14.13 for the new DCP, and the 2.14.11 for the first one. Here is the metadata.xml file, for the new version of the movie.
metadata.xml
(8.99 KiB) Downloaded 5 times
What do you mean with "data rate"?

Post Reply