Audio goes out of sync towards the end of the take

B

bogatyr

Active member
Hi there, I'm editing a short film shot at 25p with sound recorded separately in WAV format. At the beginning of each take there is a clap which I use to sync the audio. Towards the end of each take, the WAV audio slowly goes out of sync with the picture and the audio from the oncamera mic. There is difference in depth between the oncamera mic audio (16 bit) and the WAV files (24 bit). I wonder if this has something to do with it. My timeline in FCP is set to 16 bit audio depth.
Thank you for your help
:Drogar-BlackEye(DBG
 
No the bit depth isn't a factor. What is 25P? Did you shoot in PAL? If your playing your video at a different speed than you shot it at that would be the problem. For instance if you shot at 24 frame and are editing in an NTSC speed of 23.98 that would do it. Or PAL to NTSC. Also if you were shooting 23.98 video (often, but not accurately, called 24P) and you told your sound guy that you were shooting 24 frame and were going to edit at video speed, they might have "pulled up" the sample rate so that it would match your "pulled down" edit speed. But since "24p" is actually 23.98p your not pulling down the video so the sound is out of sync.

Anyway I suspect one of you pulled up (or down) and the other didn't. It can be fixed but you have to figure out which happened.
 
video was shot on a DVX100 PAL and the audio was recorded on sound devices 744t with 5 wireless lavs

thanks for your replies
 
check the tc on the 744 stamp.
do you work at 25 p or did you slow down it to 24 with film composer ?
 
how do you synk it ?
did they used tc clapper or regullar sticks , you will have to ignor the tc on the 744 files
 
the director clapped his hands which we hear in both the oncamera and the 744 mics. then i sync it by the clap
 
The TC while wrong isn't causing drift. sound files don't playback at different speeds based on TC. TC is just a positional thing, and it's only stamped at the head. But I would be highly suspicious of the sample rate. The mixer was obviously out of the loop so IF he thought you were shooting in 24 and then editing in 29.96 he may have recorded at a pull up SR. That would cause your problem.

Of course this all begs the question of why you were shooting PAL in the US with a camera that can shoot 23.98p but that's another thread.
 
maybe becouse it looks better :-)
all the film reliece for shorts for festiavls could be done in 25 , for dvd it really doesnt matter .
probably you are right and there was pull down involved
 
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