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Final Cut Audio Sync Problems – Dual System Audio using DSLR
Hi, so I’ve been an assistant editor for awhile now, but I’ve recently ran into a problem I haven’t before.
I’m dealing with dual system audio (the audio was recorded externally from the video), and part of my job is to sync the two together. I’ve got my final cut workflow down, using the merge clip function.
So when I sync them up, there is a slight slip in the longer clips. My question is what is the best way to solve the slip problem, is there a way to change the audio (by changing the sample rate) to sync it to the video?
Video =
- Recorded off of DSLR Canons (h.264)
- 23.98 fps
- transcoded using FCP Canon plugin to prores422 (still 23.98)
Audio =
- Recorder Sound Devices 788T/CL8
- Sample Rate 48KHz
- Bith Depth 24
- Frame Rate23.97 (For Time of Day Code)
- Poly BWF
- delivered in both .wav and .mp3 formats
Given that the sound guy acknowledged the TDC in his notes as 23.97 it seems he knows what we were recording at.
There is about 200hrs of video footage and it’s all been transfered to the prores format before it got into my hands (they had an out of camera transcoding workflow). I’m not familiar with audio programs, but I’m a quick study and I’m trying to get this solved off the clock (so I can come to work with an answer) – i.e. timely responses would be GREAT!
Thanks so much for all your knowledgeable advice.
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4 Replies
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23.97 is not a standard frame rate (if it’s even possible). It could be 23.98 (actually 23.976) or 29.97. If he recorded in 29.97 then that would cause slippage. You can download Wave Agent from Sound Devices. It will show the clip’s parameters and it can be used to change certain of those parameters. Be certain to backup your files before playing with this as it will change the file.
John
MacPro 8-core 2.8GHz 8 GB RAM OS 10.5.8 QT7.6.4 Kona 3 Dual Cinema 23 ATI Radeon HD 3870, 24″ TV-Logic Monitor, ATTO ExpressSAS R380 RAID Adapter, PDE enclosure with 8-drive 6TB RAID 5
FCS 3 (FCP 7.0.2, Motion 4.0.2, Comp 3.5.2, DVDSP 4.2.2, Color 1.5.2)Pro Tools HD w SYNC IO & 192 Digital I/O, Yamaha DM1000, Millennia Media HV-3C, Neumann U87, Schoeps Mk41 mics, Genelec Monitors, PrimaLT ISDN
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My fault, it is 23.98
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I’d still look at the audio with Wave Agent to make sure it’s actually 23.976, not 23.98. If it’s 23.980 that would cause drift. I’d also check that the video footage is really 23.976 and not 23.98 or 24. That, too, would cause slip. Oh, I just noticed you mentioned mp3s. Under no circumstances should you use mp3s with FCP. BTW, how long is one of your long clips? And, do you know if the camera and 788 gen-locked in any way?
John
MacPro 8-core 2.8GHz 8 GB RAM OS 10.5.8 QT7.6.4 Kona 3 Dual Cinema 23 ATI Radeon HD 3870, 24″ TV-Logic Monitor, ATTO ExpressSAS R380 RAID Adapter, PDE enclosure with 8-drive 6TB RAID 5
FCS 3 (FCP 7.0.2, Motion 4.0.2, Comp 3.5.2, DVDSP 4.2.2, Color 1.5.2)Pro Tools HD w SYNC IO & 192 Digital I/O, Yamaha DM1000, Millennia Media HV-3C, Neumann U87, Schoeps Mk41 mics, Genelec Monitors, PrimaLT ISDN
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Ok. Delete all of the audio out of your project.
Set FCP up in a 23.98 easy setup ( control-q).
Quit FCP.
Reopen FCP.
Reimport your audio.
It should now be in sync if you follow those steps.
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