44 khz -48 khz Audio
by Devin Crane
on
Jun 26, 2008 at 3:59:00 pm
My original audio was compressed too hard and has a lot of distortion and am trying to take an audio recording from a CD of the same shoot but mixed on a different board and make it work. Is this possible? In times past after I match up the audio, over time it looses sync. Any work around in FCP or Sndtrk?
Re: 44 khz -48 khz Audio by Dave LaRonde on Jun 26, 2008 at 4:41:49 pm
[Devin Crane]"My original audio was compressed too hard and has a lot of distortion..."
I doubt it's the compression. A common cause of distortion is overmodulation. Are you sure you didn't simply record your audio too hot, or inadvertently record at a mic level when it should have been a line level?
"...trying to take an audio recording from a CD of the same shoot but mixed on a different board and make it work. Is this possible? In times past after I match up the audio, over time it looses sync. Any work around in FCP or Sndtrk? "
I'd use quicktime to convert the 44.1 kHz audio from the CD to the 48 kHz audio that FCP likes, because you can open the audio, then immediately export as 48 kHz files. I do it all the time for our station music package: works like a charm.
Of course, if the audio's overmodulated on the CD, you're good & truly hosed, and your absolute BEST option is to re-shoot. Fixing overmodulated audio is Hell On Earth, if not downright impossible.
Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA
Re: 44 khz -48 khz Audio by Eric Susch on Jun 26, 2008 at 5:00:03 pm
It shouldn't lose sync if you convert the audio to 48 kHz as Dave suggests. Actually it shouldn't lose sync if you load a 44.1 file and render the audio, but FCP may be doing some funky math in the background on import, I don't know. Best to convert to 48 kHz first.
Re: 44 khz -48 khz Audio by Devin Crane on Jun 26, 2008 at 5:13:37 pm
The dialogue is getting off over time. If I sync the 44kHz audio to the 48 kHz it stays in snyc for a little while but gets off over time even after I convert to 48kHz. I think I need to do some sort of pulldown in order fix this, but I'm not sure how.
The compressor didn't have the look ahead set far enough thus the distortion. We have the output set to -10db and was still distorting.
Re: 44 khz -48 khz Audio by Eric Susch on Jun 26, 2008 at 7:56:50 pm
Were you shooting film? Or HD at 24 or 30fps? (as opposed to 23.98 or 29.97) If so then yea, you'll probably have to do a pull down. Not sure how to do that with Final Cut. It's been a long time since I've done double system.
If you're shooting video then your problem is something else. When you say it's "getting off over time," how much time are you talking about, a minute? An hour? By how much?
Re: 44 khz -48 khz Audio by Devin Crane on Jun 26, 2008 at 8:24:28 pm
Shooting SD 29.97. I can understand why the CD is off it's not synced up to a word clock like our TV Audio board is. I eventually slowed the audio down from 100% to 99.999% with the speed adjustment and that has brought me to a very close sync. I don't believe my problem was the actual conversion from 44 to 48, the Front of House board is not synced with our word clock.
