How to restore Audio synch

RWatts wrote on 6/11/2007, 8:39 AM

I captured a large file, 56 minutes through my dazzle box, and the video and audio are great, except that after about 12 minutes the synch slip is obvious and it gets worse to the end of the avi file, where the sound is delayed about a second. (The whole video is one file/scene/clip). I burned this file to DVD and apart from the synch, it is great.
I should be able to "un-stretch" the audio to match, but the instructions are unclear and when I select "Synchronize" the options are greyed out. The a/v tracks are locked together.
I realize that there are better ways to capture, but that is not an issue right now, I've got to fix what I have today.I will really appreciate any comments,
Thanks

Comments

Tim L wrote on 6/11/2007, 9:38 AM

The Synchronize options are greyed out because your audio and video clips ARE in synch as far as the timecodes are concerned. Those options help when you've ungrouped audio and video and then accidentally moved one or the other a bit.

But if your audio is clearly out of synch with your video, you'll have to stretch/shrink it to match.

By default your audio and video track are grouped together. At the top of your VMS window is an icon that looks like an open padlock with a few little rectangles. Click this, and VMS will let you move/adjust one item in a group without affecting others in the group. (I think the icon is labeled "Ignore Event Grouping".)

Now go to the end of your clips. Hold down the CTRL key and drag the end of your audio clip to the left. This lets you stretch/shrink the length of the event. A zig-zag line apears on the timeline to indicate that you have stretched this event.

Play some audio, ctrl-adjust some more, etc, until you get it where you want it. If you have any good visual cues in the video at the end -- some action that made a loud noise -- you can also look at the audio waveform and ctrl-adjust the end of the clip so the spike lines up with the visual event.

Remember, use CTRL-drag on the end of the even to stretch or shrink the entire audio track as necessary. If the audio turns pink, you have accidentally MOVED the audio left or right. Right-click and select "synchronize > by moving" to put the audio clip back where it should be.

When all done, click that padlock icon again so you are no longer "ignoring" event grouping.

Tim L

RWatts wrote on 6/11/2007, 9:46 AM

Tium:
That's great! Thanks, i'm on it now, hopefully I can get it together. Fortunately the documentary has long stretches of voiceover, so I only have to adjust about 10 events. I am splitting the file into smaller events now. It is amazing how little elay looks terrible on the video, so I overcorrected at first.
Thanks again,
reg

Tim L wrote on 6/11/2007, 2:37 PM

If you have the event split into pieces, you might have to both move and ctrl-stretch the audio to get it to line up. Start out moving it left/right until you get it matched up at the start of the event, then ctrl stretch to line it up at the end of a particular event.

Another possibility -- perhaps better overall, but maybe not worth the trouble now if you're already close to finished using the above method -- would be to take the entire 56 minute into its own little temporary project, ctrl-adjust the audio to get everything re-synchronized over the entire 56 minutes, render that out as a new DV-avi (or widescreen if appropriate), then use the new file for your project. That way you really wouldn't need to adjust each little segment that is used in your documentary.

Tim L