carl wrote: ↑Mon Nov 29, 2021 11:19 pm
What happens when you try to make the new DCP containing the atmos track? How did you do it?
The first thing I did was to study how the Atmos DCP I'm working from was made. Basically, it's like a normal DCP but it has an extra MXF track in addition to the audio and video MXFs. The audio MXF is presented as being 7.1 but the underlying file contains 16 tracks. That extra Atmos MXF file is listed in the Assetmap XML, where it's referenced as the a "chunk", just after the audio "chunk", but before the video one.
Here are the 3 strategies that seemed to have some potential in my tests so far:
Create a new DCP from scratch by importing my new DPX sequence as a video source, combined with the Atmos MXF and the 7.1 Audio MXF. I used the "Add file" function in DCP-o-matic to import the those 2 files, and "Add Folder..." for the DPX sequence. The Atmos track does load, and it has ATMOS written in brackets at the end of its name once loaded in the "content" window of DCP-o-matic. That Atmos track does not have an "audio" tab: it only had timing. I did check the timing and made sure all files were starting on the first frame - they do by default. The Atmos track also has the proper duration (00:01:25:09) when I import it. If I try to open the timeline though it will crash most of the time, giving me an error message telling me to send Carl (that's you I think !) an email about this : timeline_content_view.cc:45
image of error window that opens twice after such a crash:
https://imgur.com/JsSI4WO
Also, after such a crash, or simply after closing DCP-o-matic, if I reload the project later the Atmos track will still show up, but with a different duration: 1639:28:46:00. Or sometimes it shows only zeroes. To fix the duration I have to remove the Atmos XMF from the content list and re-import it.
If I render a DCP from this project, I get a working DCP with 7.1 audio MXF containing 16 tracks, but no sign of an Atmos MXF whatsoever.
Create a new DCP from scratch by importing my new video track as a MXF (so no re encoding is required for the video) and matching it with the Audio and Atmos MXFs from the original working version. This gives the exact same result as above: it produces a working DCP, but the Atmos track is nowhere to be found.
Load the original working DCP containing the Atmos track and replace the video track with a new one in the timeline. I was wary about working with the timeline since I had experience so many crashes when I tried that after having loaded an Atmos MXF, but if I load those as a DCP instead (using the "Add DCP..." function) then it works well. The Atmos track doesn't show per se on the time: you can only see the video and the audio track there. But I was able to change the video track by putting my new video MXF over the old one, and not touching anything else. This also produces a working DCP, but without the Atmos track once again, just the 7.1 audio is there, sadly. If I try to do the same procedure but with "Use this DCP audio as OV and make VF" it creates a DCP without any audio track, not even as a reference in the Assetmap.xml.
If I load the resulting DCP in DCP-o-matic player, and apply the "verify DCP" function it tells me "DCP validates OK".
If you think it might help you, I can send you the Atmos certified DCP file I'm working from. It's just under 2GB.