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#1
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24p - 23.976 fps video & 24 fps audio
Hi
I am starting the sound edit on a film shot on the Canon 5D. The film was shot at video speed 23.976 fps, with the sound shot seperately at 24 fps. As the Canon 5D has no way of receiving external TC or audio feeds (from what I understand), sound has to be re-sync in post using the clapperboard. I have been brought onto the project at a stage when the sound rushes have already been loaded into Final Cut Pro 7, and sync up to clapperboard and the reference audio there is from the Canon 5D built-in mic. The problem picture department are having (I am yet to receive any material) is that the sound rushes start off in sync, but slowly start to drift out of sync (running longer), to a degree that after 5 minutes or so you are looking at over 2 frames difference. I am assuming that at the stage the sound rushes were imported into Final Cut Pro some kind of automatic pull-up / pull-down should have been carried out, but unfortunately it hasn't so this will need to be fixed by us in sound post. I would be very grateful if anyone can give me a quick breakdown of the usual 24p HD workflow, and if anyone has ny suggestions about how the 24 fps sound rushes can be fixed, and hopefully automatically converted/processed upon import into Pro Tools HD. Thanks in advance |
#2
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Re: 24p - 23.976 fps video & 24 fps audio
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One way to deal with it is to make edits in the audio, either snipping out tiny bits or adding tiny bits on a regular basis, every 30 seconds to a minute. If the material does not allow that, like a musical performance, then you'll have to find the correct amount of speed change/pitch change for a longer take, either by experimentation or with a calculator. |
#3
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Re: 24p - 23.976 fps video & 24 fps audio
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The sound is drifting because of the FC"P" 24fps bug (which apple calls a "feature"). Read the sticky about the FC"P" bug. Your sound files are just fine since they were recorded at 100% speed and 23.98 if your reference. You only used the wrong TC so FC"P" thinks it has to pull down the audio. It´s a simple play-back issue. Try this: Ask them to give you a shot with clapper board at original speed (23.976). Import the video into PT. Import the sound to PT as well (don´t apply any SRC!!). Make sure neither the video nor the audio pull-down is on. Line up the audio. I´d make a bet that they will run in sync just fine.
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#4
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Re: 24p - 23.976 fps video & 24 fps audio
I thought it was the FCP bug at first but the amount of sync drift SZE reports, 2 frames in 5 minutes, is much too small for it to be caused by the FCP bug. That would be 7.2 frames each 5 minutes.
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#5
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Re: 24p - 23.976 fps video & 24 fps audio
Thanks both for your replies. Having read into this a little more, I am starting to also think that this is a simple case of no master tc device being on set to keep camera, sound equipment, etc. in perfect lock. So we'll just have to re-sync manually where necessary.
I will definitely read up on the FCP bug though also, as it sounds like something to be aware about. Thanks again. |
#6
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Re: 24p - 23.976 fps video & 24 fps audio
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#7
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Re: 24p - 23.976 fps video & 24 fps audio
I heard reports that the frame rate of the D5 can fluctuate and what was the audio recorder is may have fluctuated as well
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