11 Replies Latest reply on Aug 3, 2014 10:05 AM by footagehead123

    Serious CS5+6 Audio out of sync on MP4 and Quicktime HD (AC3/AAC) export problem




      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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