Lining up Multi-Reels of Content and audio

[Barak Epstein]

hi - long time user. first time poster. I'm having a hard time lining up audio and video content in TimeLine mode. Its super sluggish and inaccurate (snapping or no snapping doesn't help)

I have a 90min project with 5 picture reels (of TIFFs) and 5 reels of audio with 6CH each. (30 pieces of audio)

I was able to adjust timing in by using the "move to the start of the reel" function for each piece of audio manually. is this the correct procedure? Also I don't think it matters what order the audio are listed in timeline mode. (ie, LFE and LS and C can don't have to all be in the same timeline)

I am using v2.9.0

anyone else doing this type of work in DCP O MATIC?

- Barak Epstein
Texas Theatre
Dallas, TX

[carl]

Hi Barak,

Please could you start by trying version 2.10.5 to see if that's any better for you?

Carl

[Carsten]

Yes, the visual (vertical) order of the audio tracks in timeline is not relevant. Position (timing) and matrix channel assignment matters.

I understand it's a lot of work to add multiple reels of video and discrete audio tracks that way. As Carl says, this has been improved lately (also, more tracks). I would assume it works better if you add video and audio all in reel sequence, adding reel by reel.

That's the reason I usually prefer integrated/interlaved files, it is less error prone.

I noticed that the most recent DOM versions seem to auto-assign single channel audio tracks in the matrix if the file names contain common designators like L, C, LFE, etc. So, if you have that arranged prior to importing, it will help. However, there is still a strong point in using multichannel interleaved audio files.


- Carsten

[Barak Epstein]

update - I got it all lined up correct but we now have very slight audio pops at the reel changes. Should I re-encode using "pads" or "pull ups" on my audios sources?

ie if the reel is 17:00:02 in content length - ill start manually start and stop it via timing mode at 17:00:00.

followup question - since my video content is also encoded in reels can I just re-wrap audio in DCP O MATIC w/o re-doing picture to save time?

[Carsten]

hmm, tough one... are you 100% sure your audio is split to reels precisely? I would also check 'Snap' and 'Keep video and subtitles in sequence' in timeline view. If that still fails, check lenght of your audio in 'properties' and compare with position/timing.

If that fails und you stll get the pops, maybe you should try to concatenate your audio into a single reel in an external editor. An alternative way to do this could also be to copy the project to a new folder, then erase all video reels from the project, and encode. This will (pretty quickly) create a contiguous black video mxf, and a contiguous audio track, which you can check for pops. It could help to analyze the issue if you load the audio mxf into e.g. Audacity (this is possible if the FFMPEG for audacity plugin is installed) and check (zoom in) what exactly happens at the reel transitions. E.g. are the pops in all tracks at exactly the same position, or are they only in select channels.


I also guess once everything is aligned, you should be able to return to 'single reel'. But I guess, if the pop problem persists, Carl would love to see your metadata file for a check.

Yes, you can add audio to an encoded video MXF later, actually in different ways.

- Carsten

[Barak Epstein]

Snapping was definitely turned on. Multi-Reel delivery is a requirement on this project. I think we will test the pads on the files. Carl! Any other suggestions are welcome!

[Carsten]

You may import single reel video/audio in DOM to avoid the pops, but still create a multi-reel DCP from it. Depends on wether the reel boundaries must be at certain predefined positions (which I wouldn't know a good reason for). That said, Carl would certainly be interested to find out the reason for these issues. In general, adding spliced content should not create these problems.

Try to send the metadata file that created the pops to Carl. He may be able to find something around the video/audio segments in them.

- Carsten

[Barak Epstein]

hmm.. so set DOP to make reels at GB limits instead of content? That could work in theory but could be trouble if there was a reel change on a piece of dialogue, etc.

Where's the easiest place to pull that log file?

[Carsten]

Unlike your bad experience with setting up separate reels, 'changeovers' in DCPs go completely unnoticed. You can have a reel split right inside a delicate audio cue and wouldn't notice it. Hence splitting by size and thus ignoring content is not a problem. At least that's how it SHOULD go. I never experienced any issues using DOMs reel splitting. However, I never actually added content split into reels before the import.

Again, try this, and if the pops reoccur, send just the metadata file to Carl to see wether there is anything bad in the content timing. And try to analyse the audio waveform of the created 'poping' audio to get an idea what happens there.

Logfile is probably useless here, as I guess for DOM everything looks normal. What is probably happening around the pops is either cutoff because of overlap, or forced silence because of a gap. All that of course given that your presplit reels have been correctly split without any padding.
Is there sample rate or frame rate conversion in the project?

You just need to send the metadata.xml file in the project folder.




- Carsten

[carl]

If you send me the metadata.xml from your project I will have a look. It sounds like maybe the timing is off by a sample or two. Email to carl@dcpomatic.com.