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-   -   AAF and vis ref audio not lined up (http://duc.avid.com/showthread.php?t=404021)

sonoftherenegade 04-07-2019 05:34 PM

AAF and vis ref audio not lined up
 
1 Attachment(s)
Hi all,

It seems that more often than not when I'm working from an AAF file, the audio from the vis ref is always just slightly ahead of the AAF audio by around 1/10th of a second. I've attached a picture, the stereo track on top is the audio from the video ref, the bottom is the source audio in the AAF.

I most always receive an h264 file as the vis ref and I use MPEG Streamclip to transcode the video format via this article:

https://www.pro-tools-expert.com/hom...vid-dnxhd.html

Wondering if anyone has run into this or has ideas for troubleshooting?

Thanks!

reichman 04-08-2019 06:50 AM

Re: AAF and vis ref audio not lined up
 
Is this coming from Premiere? AAFs from Premiere always fall on the timeline in the wrong place. I use a 2-pop or the reference audio waveform to match sync. Clip group the whole AAF and spot. The only video platform that does everything right in regards to AAF is Media Composer. Resolve has other problems, and FCPX... well, words won't work to describe that nightmare.

sonoftherenegade 04-11-2019 05:50 PM

Re: AAF and vis ref audio not lined up
 
Thanks reichman! Yes, most of the projects I am sent are from Premiere. I recently had a project come from FCPX (Luckily I was able to convince the editor to use X2Pro) and had a similar issue.

It sounds like you're suggesting I move the AAF audio to line up with the vis ref, which makes sense. I guess I just didn't feel confident that I wasn't doing something wrong with importing the vis ref and that maybe the problem could have been the other way around if that makes sense.

So in summary, it is usually safe to say that the AAF audio should be moved to line up with the vis ref audio?

reichman 04-11-2019 06:18 PM

Re: AAF and vis ref audio not lined up
 
[QUOTE=So in summary, it is usually safe to say that the AAF audio should be moved to line up with the vis ref audio?[/QUOTE]

This is a tough one, because I've seen crummy codecs like AVC with a ref track that once imported into Pro Tools is slightly off. So sometimes spotting the AAF to the first frame of the video is actually more accurate. So many variables...

...and there are people on this list who have exhaustively tried all the AAF output settings in Premiere and probably have better info.

You're also in the zone for owning a Syncheck or a Sync2One!

Ray JB 04-12-2019 04:55 AM

Re: AAF and vis ref audio not lined up
 
Quote:

Originally Posted by sonoftherenegade (Post 2521905)
So in summary, it is usually safe to say that the AAF audio should be moved to line up with the vis ref audio?

Eeek why would you do that? There is often no way to tell how the editor made the vis ref guide track, hence no way to guess the timing delay on the Guide track. They could have used a plug-in (i.e.: a compressor or even a chain of plugins) that introduced latency to print the guide track and therefore the guide is running out compared to the AAF.

Also, imho H.264 sucks, get them to give you DNx or ProRes codec movie files from their Editing application rather than H.264. Please don't rely on your own video conversion processes to provide a guide track that is absolute sync. I've tried all the conversion methods and I've noticed varying audio sync in the converted video files in all of them!

Get the base-lines established. Demand that your picture editor to give you head and tail pops. Check the pops both in the AAF and the Guide track. Do the head and tail pops in the AAF match to the guide track head and tail pops by the same amount? (Same offset?). Grid mode in ProTools is your friend here. If so then you've got to choose a reference point. I would not rely on a guide track to guarantee absolute sync and move the AAF to match that. Then you are in wavy gravy land! That's what pops are for.

Next thing, can you guarantee your system is playing in sync? OK assuming it is, then does the AAF look "IN SYNC"? Hopefully it does. If you have the same offset throughout the project and you've got a 1/10 sec offset in your guide track, then regard your AAF as the reference. If your editor has printed pops head and tail then you can easily see what's up.

So in these scenarios, with wiggly pictures and guide tracks that are out by a small amount, you MUST align the pops of the guide track to the visual 2 pop frames. If you shift the guide track to align exactly with the visual 2 pop and the sync holds to the end pop then you are all good. And if that matches the AAF the whole way thru then job done! You're in sync.

Pops are the ANCHOR! Remember that even if there ends up being some sort of wildcard offset that you never knew about due to some bizarre technical snafu, then if you are consistently offset for some reason, then you can easily re-allign the entire show via the pops at any stage.

I've seen so many Guide tracks not being "in", I could paper a wall with them. Set your reference and never accept any job without the head/tail pop anchors.

sonoftherenegade 04-22-2019 08:08 PM

Re: AAF and vis ref audio not lined up
 
Thank you guys so much, this is such helpful information. I really appreciate it!

gwhatley 04-22-2019 10:00 PM

Re: AAF and vis ref audio not lined up
 
Quote:

Originally Posted by sonoftherenegade (Post 2522708)
Thank you guys so much, this is such helpful information. I really appreciate it!



Strongly agree with RayJB. And remember, you are adding another link in the chain of “where things could go awry” when making your video conversion.

Along the lines of what reichman is saying, using “Catchin’ Sync” app for iPad (he mentions other good ones), to make absolutely certain your internal sync is good, is step 1. Know that your rig is right, that you can trust it and have solid technical reasons to do so.

Just occurs to me: I suppose if the Guide Track itself has a 2-pop, you could use the app to test it to determine whether the AAF or QuickTime ultimately is correct, and settle this once and for all! It would only be a single point of reference, but it could work. For additional points of reference, you could use visual edits (hard cuts) in the piece itself, and place pops that align as the guide track vs as the AAF in side-by-side tests.

But my instinct in general would be to consider if, in grid mode (NOT relative grid mode), the AAF 2-pop falls correctly on the edges of the frame, then I would consider that my True North.

The place I’ve seen this rule broken are for films shot in 24 FPS that were converted to NTSC for editorial. Those 2-pops were always off the video frame edge.


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huub 05-07-2019 11:43 PM

Re: AAF and vis ref audio not lined up
 
In my experience this happens when the audio in the h264 is compressed.
If they can export a video with wav audio you should be fine.
(And leave it unimpressed when you transcode)
The video does stay sync after compression/transcode in my experience.
It's just the transcoded audio that's off.


Huub

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