Final Cut Audio/Video sync

Discussion in 'Digital Video' started by scisport, May 12, 2010.

  1. scisport macrumors newbie

    Joined:
    May 12, 2010
    #1
    Yes, I realize this has been discussed before, but for the life of me I cannot find the answer. So here we go.
    - FC version is 7.0.2
    - OSX is 10.6.3
    - Processor 2.8 Ghz Intel Core Duo 2
    - Memory 4 GB 800 MHz DDR2 SDRAM
    I have used FC before and well acquainted. Recently I took a brush up course and used material provided in a book DVD. Had no issues while practice editing with this material.
    Now have material saved I want to edit with. All video is saved on an external and in MOV format. No worries getting in imported in FC. However, every video I use starts to audio slide and by the time it reaches around halfway, full blown out of sync. Not by much, but it's definitely there.
    I even took these videos and re-saved them in MOV format and same thing. With all this RAM there should be no need to shut anything down, but I did so. Same thing.
    The interesting part is when using the test videos that were supplied on DVD and were imported into the MAC, no worries. Now I AM bringing those videos over from a saved file on the MAC itself, but that should make no difference. When bringing over the external movies into FC, they should react without a hitch.
    Here's the fun part. ALL of these videos play perfectly on IMovie. All of them. So this makes me think there's something in the FC settings at work here. Then again, why did it not fault before?
    One more thing. I recently upgraded to Snow Leopard and have seen a few glitchy items here and there. But this is the oddest.
    Would really appreciate thoughts and suggestions. Frustration is setting in. And thanks
     
  2. AWalkerStudios macrumors member

    AWalkerStudios

    Joined:
    Nov 25, 2007
    Location:
    Austin
    #2
    What are the frame rates of the video files? Check them against your sequence settings. 24p footage brought into a 23.987 timeline will play back .1% slower and the 48Khz audio (which is meant for the 24p) will then slide out of sync.
     
  3. Cousin Dirk macrumors 6502a

    Joined:
    Jan 1, 2008
    Location:
    London, UK
    #3
    What bit rate is the footage recorded at? I had a similar problem with footage from a DV camera that was for some reason recording the audio at 12-bit instead of 16-bit, which caused a gradual de-synchronisation of the audio and video over time. Changing the bit rate solved the problem.
     
  4. scisport thread starter macrumors newbie

    Joined:
    May 12, 2010
    #4
    Think I may have found the issue with a little help. Most of the video I use is via a software capture program (IShowU, excellent software and quality), and there seems to have been an issue in the format the capture was recorded in versus what FCP was reading. Seems to have settled down so I'm going to keep an eye on this and see what happens. THanks for the idea on the frame rate, that's something I always check. The bit rate also is something I keep track of just in case. Think in this case I learned something about the use of capture programs and their specific recording formats that has a hinky effect on FCP.
     
  5. iThinkergoiMac macrumors 68030

    Joined:
    Jan 20, 2010
    Location:
    Terra
    #5
    24p is 23.987 fps. Just like 30p is 29.97 fps. At least, just about always. For example, my Canon HV20 records 24p at 23.987 fps (for the knowledgeable here, yes I remove the pull-downs first). Just about everything 24p in the NTSC world is 23.987 fps. You're right about something recorded in true 24p (24 fps) but that's fairly rare in my experience.
     

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