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Audio Drifts Out of Sync

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Ryan Brewer
Audio Drifts Out of Sync
on Jan 10, 2015 at 5:05:48 am

I am at a loss. I have several .avi files that I am trying to convert to .m2v's in order to create a DVD in Encore. The original avi's play fine all the way through with no audio syncing issues but everytime I try to transcode them or convert them to a different format the audio slowly drifts out of sync usually becoming most noticeable toward the end of the video.

I have tried everything I can think of short of going through all the codecs one by one and hopping one hold the sync.

I've tried converting to an Uncompressed AVI, to an MP4, to an M2V. I've tried matching the kilohertz and changing the kilohertz. I've tried exporting audio only from Premiere. I've tried to let Encore handle the encoding. I even tried using VLC media player to convert them once I got desparate. I also found a few different forums - some here on Creative Cow - that talk about exporting as a certain format then converting that file to an m2v. Nothing is working!

Here are the properties from one of the problematic AVI files:

Type: AVI Movie
File Size: 174.4 MB
Image Size: 624 x 352
Frame Rate: 23.97
Source Audio Format: 48000 Hz - 16 bit - Stereo
Project Audio Format: 48000 Hz - 32 bit floating point - Stereo
Total Duration: 00;21;23;15
Average Data Rate: 139 KB / second
Pixel Aspect Ratio: 1.0

The files vary in video data rate, video total bitrate and in audio bitrate but none of them will sync properly when I try to encode them. Does it have anything to do with the descrepancy between source and project audio format as seen above? Is there something else inside that pesky AVI container that is screwing me up?

I am no encoding expert by any means so if someone could please shed some light on this for me it would bring me a world of peace. Thanks in advance.


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Ryan Holmes
Re: Audio Drifts Out of Sync
on Jan 10, 2015 at 11:31:50 pm

Some questions:
(1) What are the settings you're encoding to (changing frame rates may cause a lack of sync...going from 23.976 to 29.97 or mixing up sample rates)?
(2) Does this happen on other machines or just one?
(3) Does this sync problem happen regardless of what format you export - m2v, avi, mov, mp4, etc? So anything you export goes out of sync?
(4) You have verified that everything is in sync within Premiere on your timeline (I assume so, but just want to eliminate that as the problem! :-)

Ryan Holmes
http://www.ryanholmes.me
@CutColorPost


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Ryan Brewer
Re: Audio Drifts Out of Sync
on Jan 11, 2015 at 3:15:07 am

Hello Ryan (pretty solid name by the way :)

I have tried every setting under the sun. Every encode setting I tried has been 23.976 because I know better than to switch frame rates but by now I am at the point where I might just switch frame rates to see if that works. Is it possible for the file properties to be false? I've certainly never heard of that before.

I haven't tried encoding on any other machines as I don't really have access to anything else. Could it be my PC that is causing the problem. I've encoded countless videos on this machine so I doubt is my computer but who the heck knows!?

The sync problem has happened regardless of the format. I believe I've tried mp4, m2V, microsoft uncompressed avi, microsoft avi, and perhaps a couple more. They are starting to blur together.

The original video file (an AVI) is in sync in Premiere and it is in sync in VLC media player and Windows media player too. One interesting thing though: I tried converting the file using VLC which offers an option to "keep original audio file", when I did that the file remained in sync but VLC encapsulated it in such a manner as I could not use it in any other program. It is strange though that keeping the original audio file and just converting the video file sort-of worked. Does that mean that the audio files are corrupted?

Any insight you might offer is much appreciated.


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