CD Audio sync

MaxStone01 wrote on 7/7/2004, 1:05 PM
I have not had this problem before, but I am suddenly unable to get audio extracted from a CD to sync up with my video project. I'm trying to sync the original musical performace recorded on CD with the video. The CD audio seems to be slower than the finished video project. I've tried every combination of capturing and rendering that I can think of but nothing works. Can anyone help? This is a serious problem. Thanks!

Comments

Catwell wrote on 7/7/2004, 1:18 PM
How much slower are you talking about? I normally have a deviation of about three frames for every ten minutes between the DV tape and my hard disk recorder. You can adjust the video for those few frames either by holding control while sizing the video, or removing extraneous frames in appropriate places.

I usually match up two ppoints in the sound track one near the start of the peice and one near the end. That way the rest of the take falls nicely into place.

It is not uncommon for two devices to run at slightly different clock rates. The only way to have pefect sync is to lock all your equipment to a master clock. I don't have funds to support such equipment, so I just adjust it in the editing process.
TheHappyFriar wrote on 7/7/2004, 1:18 PM
Have you tried stretching eigther the video or audio to fit the other?

What did you record the video on (DV, VHS, etc)?
MaxStone01 wrote on 7/7/2004, 2:51 PM
The video is from a DV source. Three cameras, all in sync, the audio from the cameras is from the same CD I'm using to extract the pre-recorded sound from, so that's why I can't figure out why the audio I hear from the original video recordings doesn't match up with the master CD. I've even tried recording the CD audio directly to my DV camera and then digitizing it, but there is still a sync problem. I have tried stretching the CD audio but that didn't seem to help.
MaxStone01 wrote on 7/7/2004, 2:53 PM
I've got several 3 to 5 minutes clips, and the audio starts going out of sync almost immediately. By the time I get to the end of the clip, it sounds like the Grand Canyon.
Catwell wrote on 7/8/2004, 12:03 PM
If it sounds like the Grand Canyon, then you are listening to all tracks at once. Your final project will only use one of the tracks at a time. Your CD is recording at 44.1 KHz. Your DV cameras are recording at 48 KHz (samples per second). Unless you connect all your cameras together with a master clock they will not stay in sync. I am not sure that you can sync a CD recorder at 44.1 to a camera at 48. It can probably be done but the processing would be difficult.

Most video is done with multiple shots and the only thing that has to sync are places where the sound source appears on screen. I record classical music recitals. The audio is continuous and is the primary information. My audio track is the base for all editing. The video must be in sync with the audio as long as the shot shows the performers (99% of the time). I only use audio from my hard disk recorder (which I use at 48 Khz 24 bit). I line up all the camera tracks on the time line and sync them to the main audio track. I stretch or compress the video tracks to match the main audio track. I then delete the audio tracks from the video footage. Now I have three video tracks and one master audio track. This works very well except when I accidentally move a video track when I am trying to resize a transition.

I use the Multicam Wizard in Excalibur to sort and combine the tracks. If you haven't used Excalibur check it out. It saves lots of time.

http://www.vegastoolsandtraining.com/