while exporting our video files and importing them into our projects to check the sync we noticed that if we export in MP4 1080p H264 format the audio is 1/2 video frame out of sync compared to the original. This happens with both original audio files attached to the original clip as well as other random audio files combined with the clip.
If we export the WAV file and import it again into the original timeline this is 100% in sync, but if we export that clip with the imported WAV file it's again out of sync.
please check the pic:
as you can see the "edit_1080p_1.mp4" files is the exported and re-imported clip, which is 100% synced to the video (from timecode 0:00:00:00) and the our of sync is about half a video frame.
This also seems to happen in CS5 as we just have tested on another old system.
Addon: It also happens with Quicktime HD Export.
If exported in AVI there is no out-of-sync, so this problem seems only to be on Dolby Digital and AAC encoded and multiplexed files.
As we found out if exporting clips with any CS5 or CS6 Version in mutiplexed AC3 format eveytime after re-importing those files back into Premiere the audio is about 1/2 videoframe delayed! So this means if you work with multiple temporary exported files, e.g. MP4 HD HQ formats your audio gets more and more out of sync.
But we also found out that if you simply convert WAV to AC3 there is also a slight delay on the AC3 file, although not noticeable on the first view, but if you switch to audio frames view it's about 1/10 frame.
I think this is a very serious error and needs to be fixed as soon as possible.
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unfortunatelly this does not solve the problem, since MP4 and H264 Quicktime is needed for exporting to final formats we deliver to various customers, so all of them are slightly out of sync.
I hope this can be fixed soon to avoid any time intensive workaround like exporting into video formats with PCM audio and encoding them with another software.
Another update while exporting in Quicktime with AAC and PCM Audio multiplexed:
this shows the difference between AAC and PCM audio export. As you can see the AAC is out of sync (qt_aac) and the PCM version is in sync with the original.
In terms of audio production half a video frame out of sync is absolutely a desaster !
And another, even worse, update:
we did several tests with just converting the H264/PCM multiplexed file to different format, MPEG2/MP2, MPEG2/AC3, MP4/AAC (both CS6 and CS5) and we just encoded the file with Procoder in H264/AAC (orange colored). And the result was, that ALL Adobe encoded files are not correctly synced to the original but the Procoder file is! Even with CS5 this was already not working.
I am shocked, that nobody really seems to have noticed that elemental error until now...
So the only working workflow at the moment is to export all files into Quicktime H264/PCM format and then user other encoders to create the final files needed, if they need to have compressed audio formats like MP2, ACC or AC3.
The Problem is not Quicktime, since it all works for multiplexed uncompressed audio even with Quicktime, but the out of sync problem also appears on almost all audio compressed (AC3, MP2 and ACC) multiplexed exports, including MPEG, M2TS, MP4. So in fact exporting all those formats are unuseable if you need a 100% synced output.
Have your testet to export in multiplexed MP4 or MPEG format and re-import that file again to put this above the same sequence you exported? Please zoom to maximum and check if the audio is 100% synced to the original audio track.
We did not noticed this error for years of working with other CS versions, which is sad enough i have to say. At first we thought this would only affect the new CS6 versions but we get it also on old CS5 versions.