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Audio Export out of Sync
So I have finished a short film (12 minutes) that was shot on film, 23.976 fps. My sound designer has given me the mixed down sound, which I brought in and everything plays back perfectly in sync in Avid. However, when I export as an .mov (with various compression settings, including same as source), the audio falls out of sync. Even if I export audio and video separately and bring them back together in Encore, the same thing happens.
I marked ins and outs for my sequence, bringing the TRT to 12:44:09. When I export the video, everything is fine, and my .mov file is 12:44:09. However, when I export the audio alone (as a .wav), it’s duration is 12:45:03.
This is presenting a big problem for me as I need to get copies of the film to the actors ASAP. Does anyone have any ideas for how to make this export properly?
Thanks in advance for any and all help.
-John
Here’s what I’m working with:
Avid 5.0.3.5
Adobe Encore CS5 (with all updates)
OSX 10.6.5
Mac Pro 5,1
2×2.66 GHz 6-core Intel Xeon
14 GB DDR3 ECC 1333 MHz RAM -
3 Replies
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Sounds like drift because of a pull-up / pull down issue. I’m assuming Avid did a frame rate conversion on the audio to match the video sequence settings, which is why it played out in sync, but not during export. However, the audio export should have followed your timeline settings…so something else may be amiss.
Try bypassing Avid…Open both your exported video in QT as well as your raw sound mix from your sound person. Match up the common in points. Do those TRT match?
Did you give the sound person a countdown and visual 2 pop & tail pop, and did the sound person give you a tail pops and head pops to test sync?
What is odd is that film/video recorded at 23.98 and audio recorded at 29.97 are still in sync – 1 second is 1 second.
Maybe the sounds guys were working in true 24 or 30…not 29.97? Maybe they did a conversion? Maybe you did a conversion when importing the audio? I’d have them verify their timeline settings and frame rate they are exporting things at.
~Michael
.: michael kammes mpse
.: senior applications editor . post workflow consultant
.: audio specialist . act fcp . acsr
.: michaelkammes.com -
Thanks for the suggestion, but the problem seems to be specifically related to the export from Avid. As far as I know there is no such thing as “framerate” for sound files, just their frequency (let me know if I’m wrong here). In this case the Avid project I’m working on is 48 kHz, and the raw sound file is 48 kHz as well. In the timeline in Avid everything matches up fine, is the proper length, and plays back at the right speed. It is only when I export (still at 48 kHz), that the audio file is extended by a second, and sync seems to be off.
I gave the sound guy a head pop (not tail, as it’s not customary for our workflow, but maybe I’ll suggest that now), and with that aligned everything throughout the film was in sync (in Avid). The problem pops up when exporting in any format, whether it’s same as source .movs, split video and audio files, or QT references.
Any other suggestions as to how I can fix this issue? Going away on vacation tomorrow and I’d hate to have to drag this with me!
And as always, thanks again for any and all help.
-John
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Audio can certainly be RECORDED at various frame rates. Standard is usually 29.97, and a big misnomer is that this is out of sync with a video source at, let’s say, 23.98. If you think about it, both are the same length. In fact, one of the things I was mentioning is that your Pro Tools user may have had their timeline at something OTHER than the rate your audio was recorded at. If they DID, then an export from PT would certainly cause sync issues when you got it.
That being said, usually if they did something as thoughtless as that, they would notice sync issues themselves when you gave them the video edit with a timecode window burn. (i.e. timeline TC would not match the window burn).
So, all of that being said – and if sync was maintained through to your Avid, we’re left as Avid being the culprit, albeit a glitch, or a settings issue.
Out of curiosity, when you gave the sound person a video export to mix to, did you create a new sequence with a mixdown? Have you laid the sound mix in THAT timeline, or, did you lay it down in a pre-mixdown timeline? Trying to eliminate variables here.
Are you 100% certain these are in sync in your time? Have you tried playing from FFOA and letting it play unattended to see if there is drift near the end…i.e. the sync gets worse at the piece progresses?
Another troubleshooting tip is to create a new project in Avid (and sometimes a new user) and import the Bin and Seq, and try an export form there, user and project corruption can do some odd stuff – although, this would be one of the strangest.
If post audio was 100%, then my gut tells me it’s a Avid settings issue, maybe in MEDIA CREATION, maybe an effect in the timeline, etc.
This is an interesting one.
~Michael
.: michael kammes mpse
.: senior applications editor . post workflow consultant
.: audio specialist . act fcp . acsr
.: michaelkammes.com
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