5 Replies Latest reply on Jan 28, 2011 9:05 AM by Rob de Boer

    Audio/video creep out of sync then latch on again

    Rob de Boer

      If I play any part of any of my timelines, the audio and video start in sync, no problem so far. Then as time passes (about 30 sec in) they start to 'diverge' from one another up until the point that they're almost a second apart (wild guess), when at some point the video 'skips' back in sync with the audio.

       

      I'm not even working with complex compositions or layers or whatever, just plain clips playing sequentially.

       

      I work only with 1080p 50fps PAL files from my panasonic SD-700.

       

      Sequences are set up as 50fps, and 48KHz, which is also the format of the soundtrack as I use an external mic (and not the 5.1 stuff from the camera).

       

      My hardware:

      i-7 950 (3.8GHz OC)

      12Gb RAM

      460GTX (using GPU for MPE)

      OS, programs, media, projects, scratchdisk, pagefile and export folders spread accross four HDDs following Harm's generic guideline

      EMU USB0404 with ASIO drivers for sound

       

      This rig is perfectly capable of playing back these files, as the program that came with the camera plays them back with no issues.

       

      Playing back at half or even quarter resolution doesn't change this behavior.

       

      Stopping and starting a timeline also brings audio and video in sync again. My guess is that this doesn't affect any exports (haven't tried that yet). But it is annoying regardless, when during editing stuff starts to run out of sync.

       

      I've searched the forum and google over to see if this is a common problem, but apparently not.

       

      I welcome any possible solution to this problem.

       

      Regards, Rob

        • 1. Re: Audio/video creep out of sync then latch on again
          firetrak Level 1

          I assume the video doesn't do this is you play it in vlc or some such player.

           

          Have you tried deleting the index and audio conform files and have PPro re-index and conform again? Keeping in mind not to touch the machine at all when its doing this, as i've found that can cause issues.

          • 2. Re: Audio/video creep out of sync then latch on again
            Jim_Simon Level 8
            I work only with 1080p 50fps PAL files from my panasonic SD-700.

             

            As a non-standard format, I suppose that might possibly be an issue.  Try recording some normal 1080i/25 and see if you get the same behavior.

            1 person found this helpful
            • 3. Re: Audio/video creep out of sync then latch on again
              Rob de Boer Level 1

              @firetrak: Yes, I have tried that. I deleted the entire media cache, re-opened the project and left the computer alone to do the conforming and whatever else it needs to do. When I came back from preparing and eating diner, it was all done, but the problem was still there.

               

              @Jim: Haven't tried that yet. Will do that and report back. I'm not sure if the cam will record 25fps though. But 1080i 50 is also a more conventional format I guess. So I will try that to figure out if this issue has something to do with the 1080p 50 format.

              • 4. Re: Audio/video creep out of sync then latch on again
                Jim_Simon Level 8

                1080i/25 is the normal video format, 1080i/50 is an incorrect way of saying the same thing (25 interlaced frames per second).  1080p/50 (50 progressive frames per second) is the oddball format that neither HDTV nor Blu-ray support, but only a very few consumer level cameras.

                • 5. Re: Audio/video creep out of sync then latch on again
                  Rob de Boer Level 1

                  I just recorded some footage of myself talking to the camera with the 1080p50 swiched off, imported it and played it back. No problems with the audio sync! I almost drew the conclusion that the odd format of 1080p50 is in fact the issue. However, just to double check, I ran some of the 50p footage again and found out that this time it synced spot on....

                   

                  For me it's too soon to say the problem is solved, as I didn't do anything to fix it. At the same time, as long as it's not there anymore I'm happy. I expect it to resurface at some point, though. It has been there for a few weeks now, I can't imagine it disappearing overnight because of nothing.

                   

                  Anyway, thanks so far for your suggestions and for clarifying the issue of 50p/50i/25i. I appreciate it.