FORUMS: list search recent posts

Audio sync drift: XDCAM EX with 722 audio recorder

COW Forums : Apple Final Cut Pro Legacy

<< PREVIOUS   •   FAQ   •   VIEW ALL   •   PRINT   •   NEXT >>
Vivian Wong
Audio sync drift: XDCAM EX with 722 audio recorder
on Oct 5, 2011 at 8:18:57 pm

Hi,
I have been using pluraleyes for the past year to sync large scale documentary projects and it has worked pretty well so far.
However I have just hit a wall with the project I'm working on right now.

These are the tech specs of the film:
1) The video was shot on a SONY EX3 (I think). The clips are XDCAM EX 1080p24 (35 Mb/s VBR). The frame rate is 23.98. The audio is 16 bit, 48 KHz, and 2 mono tracks.
2) The external sound was recorded on a 722 portable recorder (http://www.sounddevices.com/products/722.htm), which produces 48.0 KHz, 24 bit mono WAV files. I believe the sound was recorded at 29.97.

From the beginning of the syncing process, I always set up the project with the easy set up solution suggested by Bruce Sharpe here in this blogpost: http://brucesharpe.blogspot.com/2009/06/dslr-dual-system-audio-999-solution....

In this case, the easy set up settings are:
Sequence Preset: XDCAM EX 1080p24 VBR
Frame Rate: 23.98
Capture Preset: HDV
Device Control Preset: HDV FireWire Basic
Playback Output Video: None
Playback Output Audio: Default
Edit to Tape/PTV Output Video: None
Edit to Tape/PTV Output Audio: Default

The audio continues to drift. These are the solutions I have tried:
1) Setting up the FCP project according to Bruce's 99.9% solution multiple times. It does not work.
2) Assigning the audio files a frame rate: Exporting the wav file from a 23.98 FCP timeline so it becomes a movie file with a 23.98 frame rate. I import it back into a 23.98 easy set up project. It does not work.
3) Importing the wav file into soundtrack pro and exporting it with a 23.98 playback rate. It does not work.
4) The following solution has yielded the most results although the audio still drifts, it just drifts less and happens further down the timeline. I threw the files into Compressor.
a) I transcoded the XDCAM video files into Apple ProRes (LT) (I chose a lower quality because this was an experiment) with a 23.98 frame rate. I exported the sound wav files from a 23.98 XDCAM EX 1080p24 FCP timeline and threw the resulting movie file into Compressor. This file was also transcoded to Apple ProRes (LT) with a 23.98 frame rate. I took these Compressor results and imported it back into a 23.98 FCP project. The audio actually drifts less. The drift happens further down the timeline.
b) I transcoded the XDCAM video files into Apple ProRes (LT) but this time I manually changed the frame rate to 23.976 in Compressor. Again, I exported the sound wav files from a 23.98 XDCAM EX 1080p24 FCP timeline and threw the resulting movie file into Compressor. This file was also transcoded to Apple ProRes (LT) with the frame rate manually changed to 23.976. Once again the audio actually drifts less, but the drift still happens further down the timeline.

Does the solution involve re-clocking the audio file through a sound program like Pro Tools, Soundtrack Pro, etc.?
Transcoding everything to ProRes?
I am officially stumped.
Any suggestions would be greatly appreciated.
I have a tight deadline so hopefully someone will see this soon and respond.
Thank you in advance!


Return to posts index

Matt Lyon
Re: Audio sync drift: XDCAM EX with 722 audio recorder
on Oct 6, 2011 at 3:58:10 am

Hi Vivian,

Have you read my tutorial?

http://library.creativecow.net/lyon_matt/fixing-fcp-assets/1

You may just need to re-import your audio files the "correct" way, which I describe in the second half. Once you import the audio incorrectly the first time, Final Cut takes a bit of coxing to force it to forget the "bad" setting.

Unless the 722 was doing something really funky, you shouldn't need to jump through so many hoops to get the sync to work. It really should work right away.

Hope this helps,

Matt Lyon
Editor
Toronto


Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2018 CreativeCOW.net All Rights Reserved
[TOP]