Multicam export results in audioproblems

Community Beginner ,
Mar 16, 2021 Mar 16, 2021

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Concerning Premiere pro 2021 MacOs on MacBookPro 2020.

 

I have a big, 1:30 hour, project where i have two multicam edits cut into each other.

Reason, the multicams are from two different show recordings.

 

One of the Multicams is nested, and cut, into the other multicam edit.

Both of them have 8 audiotracks and when i don't use the audio of one i delete it from the timeline and therefore use the other.

 

It's a big sequence and it runs pretty smooth on the MBP. Allthough at the end of the complex edit Prem got a bit slower and less snappy. But no big hickups.

 

But when i export the multicam edit to H264 or HEVC with stereo audio, it results in a clip that loses audiosync after some minutes. I checked the timeline several times, all fine. After i restart and reopen premiere poject everything is still perfecly in place. Re-render and... nope.. the file starts off fine but loses audiosync after some time. This is very frustrating because there is, as always, no time to troubleshoot this.

 

Any ideas? Thanks

TOPICS
Audio, Editing, Error or problem, Export

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Adobe Community Professional ,
Mar 16, 2021 Mar 16, 2021

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Is that footage VFR? Variable frame rate? I would about expect this result if it is. That is what most screen-recording apps and phones produce. Some apps like OBS can be set in the options to record CFR, some can't.

 

An easy way to check the media is often to simply look at the Properties in PrPro. If it's something like 29.01 for FPS, then it's VFR. Another way is with the free utility app MediaInfo .

 

Download that app, and drag/drop a file onto the icon on your desktop. The app opens, select the "Tree" viewing option, and see what it says. I'll include a sample image below. Notice that down in the Video section, it lists Frame rate mode as "constant", so this clip is CFR. If it says "variable" there, it would be VFR.

 

If your media is VFR, then it's best to convert to CFR in the also free utility app HandBrake.

 

Import the file into Handbrake, and on the Video tab there, click in the CFR little circle button, and set a specific number for the frame-rate in that box. Then set the compression to "near placebo". Use the file created by HandBrake to replace the media in PrPRo.

 

Neil

 

MediaInfo TreeView.PNG

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Community Beginner ,
Mar 17, 2021 Mar 17, 2021

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Hi Neil,

 

Thanks for your reply.

 

No, all footage is HD prores proxy that originated from 100mbit 4K gh5s footage 25fps.

I would never ever work with compressed footage in multicam edits on an hour+ film. Asking for trouble. Even the original GH5s footage would be too heavy in a project this size.

 

What seems to work is first export the film to Prores and after push it trough AME into an H264/HEVC file for reviewing. But this is still time-consuming. Can Premiere fix these 'out-of-timeline' render issues?

 

Grtz

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Adobe Community Professional ,
Mar 17, 2021 Mar 17, 2021

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That is a frustrating work-around. And shouldn't happen, as the Me 'engine' is the same one used within PrPro according to the engineers when there are differences between them. Except that then they go into the old "well, now ... if X is actually Y, then Z won't work as we expect ... hmmmm .... ".

 

Queing an H.264 export from PrPro over to Me should be the same as opening the sequence in Me and exporting H.264. That doesn't work, huh? You have to output the ProRes from PrPro, open that in Me and export to H.264?

 

Neil

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Community Beginner ,
Mar 18, 2021 Mar 18, 2021

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Hi... cheers for your reply.

 

Me and my colleague editor are working it out. And we have found the culprit.

The edit is with a 8x stereo audio multitrack. The first two are stereo mixdowns recorded from multiple outputs. And it seems that the first 2 stereotrack don't stay in sync with the other (reaper) multitrack.

 

This is very odd because those stereo mixdowns are recorded with a Blackmagic monitor and should be perfectly fine with all our camera's and multicam edits.

But nothing is less true. The sync just gets worse and worse over time.

 

Having that stereomix in two seperate multicam edits that are than intercut with eachother...... you can understand it is very hard to find where the hell this is going wrong!

 

Solution: Dump the stereo mixdown track and keep the reaper multitrack is prime. Now re-edit all the little off-rythm cuts and it should pan out with the audioguy.

 

Cheers

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Adobe Community Professional ,
Mar 18, 2021 Mar 18, 2021

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Aren't all these mix & match fixes fun? Sheesh ... 😉

 

Neil

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Community Beginner ,
Mar 19, 2021 Mar 19, 2021

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It's crazy!

Especially that you consider that is seems different devices have a different interpretation of time! 

The project has been a hassle, yes. But the client has been a handful too. To make things even more fun. 😞

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Adobe Community Professional ,
Mar 19, 2021 Mar 19, 2021

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Clients ... yea, sometimes it's the old can't live with 'em, can't live without 'em  ... sigh.

 

Which is part of what makes having to fight the software while trying to keep very calm ... peaceful ... and carefully focused with the client even the more frustrating.

 

Neil

 

 

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