Audio Out o Sync (same frame rate)

[Motion]

Hi!
After importing video and audio files for my feature, the preview seem getting progressively out of sync (audio ahead of image).
The was no problem with the mp4, and Ive checked the AE export and its all 24 frames, the same frame rate as the DCP project.
Ive generated a DCP and the results seems he same in DCP-O-Matic Player.
I really dont know what else to do.
Thanks

[carl]

Hi

Please email the metadata.xml and log files from inside your project to carl@dcpomatic.com

[Motion]

Sent

[Carsten]

So, you imported them as separate files for video and audio? Until which stage of that separation had they been still in sync? Is that 'MP4' file in sync? Why didn't you import that MP4 file for video and audio?


- Carsten

[Motion]

The original project was an After Effects project, in which the video output was a folder of jpg 2000 and the audio straight from the main timeline. This project was 24 frames.

This is a 60 minute film so my computer crashed if I tried to export a Prores or any other format other than H264.

I didn't want to a DCP of my feature out of a h264 export so I imported the Jpg 2000 folder and the audio separably.

Hope this makes sense,

[Carsten]

Are you sure that the frame rate and audio sampling rate comply? Also, quite often when people use image sequences, there are dropouts in the frame sequence. This of course can be hard to track down by checking the image folder for a 60min project. However, by comparing the amount of files in the folder and the total legth in DCP-o-matic, one may find a hint towards an issue like that. An MP4 file that plays in sync may serve as another tool to diagnose the issue. e.g. load it into DCP-o-matic, and compare it's length or frame count with the separate audio, or the frame sequence.

Is your separate audio sample-accurate trimmed to the image, or is it longer or shorter? You may check issues like this in Timeline-View. Under Timing/Triming, you may also change the frame rate reference for both video and audio, so you may check wether it's e.g. a 24/25 fps misinterpretation quickly. The result should immediately be visible in Timeline View.

- Carsten

[carl]

From the metadata it looks like both video and audio are more-or-less exactly 1hr long (give or take a second). How badly out of sync is it towards the end of the film? And does it start off in sync?

[Carsten]

After importing content into a DCP-o-matic project, RightClick - > Properties will give you the length of both video and audio content in frames.

Just for finding a discrepancy, I would import the J2K sequence, the split audio, and the MP4 export, and check how many frames are reported there for image and audio.

BTW - when creating the DCP, you should check the 'Re-Encode' Option under DCP->video. Otherwise, DCP-o-matic will passthrough the J2K images from AfterFX into the DCP - which will most likely result into a non-compliant DCP.

- Carsten

[Motion]

- When imported a h264 version it plays beautifully
- The sync problem gets progressively worse throughout the film, culminating significantly worse in the end.
- The video is 86428 frames and the audio 86401
- The AE project is 24 frames as well as the DCP. Any change in the frame rate makes matters worse.
- In the Audio tab "Play Length for audio is "1:0:0:1" and for Video: "1:0:1:04"

To make matters stranger I've made a DCP of the same film a year ago with an earlier version o DCP-O-Matic and the preview isn't that bad (and is consistent trougout).

- I dindt use the 'Re-Encode' Option, Ill try that.

Thanks!

[Carsten]

What number of frames is indicated for the h264 content under 'properties'? What play time?

- Carsten