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Are GH2 audio and video in sync ?
  • duchduch

    This might seem like a stupid question, but are the audio and video recorded on a GH2 in perfect sync ?

    I ask because Canon EOS audio is out of sync by 2-3 frames (depending on the framerate), which makes it almost useless to me due to the huge amount of manual re-syncing required.

    (if this question have already been answered : sorry)

  • 6 Replies sorted by
  • fatpigfatpig

    I assume you do not own a GH2? I did not do or see a test, but i assume i would have noticed, since i do a lot of interviews with it, and sync the audio by the GH2 audio file. does seem to be on the spot.

  • alcomposeralcomposer

    @duch If the Canon EOS is out by 2-3 frames consistently is it not simply a matter of correcting the audio during import with a script?

  • DouglasHornDouglasHorn

    @dutch - Yes, the GH2 is out of sync by about 2 frames (@ 24fps). Canon is out of sync by 3 frames @ 24fps (audio is ahead of video). I use double-system sound and I've synched a lot of footage so I can say this with certainty. Two frames is not a lot so many people miss it. But synching to a slate makes it obvious.

    @alcomposer - I've searched for ways to re-sync audio by a set number of frames via a batch script but haven't found one. If you know of one for FCP I would be most grateful. (Or any other NLE--I might just switch for this feature.)

  • mrbillmrbill

    I've never noticed sync problems with either dslr at 25fps viewing on a crt broadcast monitor.

  • DouglasHornDouglasHorn

    @mrbill - Have you checked against a slate? I've heard that the delay is a product of audio being recorded in real time while the video is being processed.

  • alcomposeralcomposer

    $ ffmpeg -i original.mov -itsoffset 0.2 -i original.mov -map 0:0 -map 1:1 -acodec copy -vcodec copy synced.mov

    (If using Prores make sure to have Prores decoder- apart from that set -itsoffset to whatever you want in seconds (currently 0.2))

    This current script also "SAVES" a copy so you may want to delete the original file, (as long as you have a copy- or its NOT the AVCHD from the cam- etc).

    This does the job- but there would be better scripts- (as well as batch scripts) its also very fast as the only work it has to do is 'copy' the files over- nothing else.

    Research the ffmpeg -itsoffset command.

    When I have more time I may make myself a Shell script for doing this in batch... (or maybe someone will beat me to it!)

    As for FCP-FCPX this could be achieved in FXPlug and Audio Units. But as its just a one size fits all thing it is better suited to external software... (mind you FXPlug can also be made to call up Shell scripts so maybe this wouldn't be so hard after all?)

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