syncing cd audio

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[Lawrence Robbin] “I know that I can sync the beginning but that it will drift off sync after awhile several frames or more.”

It shouldn’t drift at all.

I’ve synced digital audio sources and digital video many times and had no drift whatsoever.

Give it a try.

Import and lay the CD audio to the timeline, then add all the “camera takes” above it.

[Lawrence Robbin]

Thanks, I’ll try it when I get the audio cd.

LR

[Ryan Mast]

Hi Lawrence,

When the band performed, did they play live, or did they play along with the track? If they played with the track, you should be able to sync it at the beginning (or middle, or end, or whatever) and the rest should be fine.

If they played live (without a metronome or click track), you’ll just have to sync sections to the track as you go — every time you cut to a new angle, check the sync. It’s not a big deal, don’t worry. I personally usually look for downbeats — or anything else with a noticeable, unique spike in audio or waveform. Put a marker on the spike. Find the same point in the song on the other clips, and mark their spikes. It’s less confusing if you try to find it in a noticeable part of the song, e.g., right before the chorus. If you’ve got snapping on, you can stack your clips on top of each other, and drag them so the markers snap together. For a subjective check, pan your song track left and the video/audio right. Keep nudging the tracks until they sound in sync. Does that help at all with what you need to do?

Good luck! I’d love to see your finished video when you’re done…

[Lawrence Robbin]

Hi Ryan – Thanks for the tip. The shoot was a single camera shoot (done as a favor for some friends) with just a bit of cutaway material. They did not sing to a recorded track, but played a live concert for a non-commercial radio station fund raiser. Working alone and rushed (excuses), I didnt have time to feed their board audio into my camcorder. Anyway, I will definitely follow your suggestions – look for where the video loses sync, mark spikes and use those to cut the video and re-establish sync where it drifts off. I speculated or wondered if workiing with FCP, I could do the following: establish sync at the beginning, look at how many frames it drifted off by the end, and “tell” FCP to make the cd audio have a length that took into account that difference – if that makes sense.

LR

[Ryan Mast]

Yeah, that’s definitely possible. Though it’s probably better to adjust the speed of the video clip, not the CD audio — if you change the speed of the CD clip, that will change the pitch of the song and you’ll lose quality. It’d be weird. Also, the band might not have performed at an exactly consistent tempo, so even if the beginning and end are synced, the middle might be off. Or it might work perfectly — play with it, I’m sure you’ll find something that works!

[Bouncing Account needs new email address]

You say you didn’t feed the audio of the show into your camcorder.

But, is the CD you’re talking about one that was recorded off of the sound board feed of the “live show?”

If this is a CD recording of the audio of the band performing in the show you shot, assuming you did not stop your camera and the CD is a straight-through recording, the CD should match-sync your video perfectly.

Once synced at the head, it should not “slip” for the duration of the song.

A digital videotape and a digital audio track, both recorded at the same time, same performance, should hold sync.

[Lawrence Robbin]

Can you change the speed of a video clip by only 10-20 frames?

LR

[Lawrence Robbin]

Boy, Matt, that would be great! I’m still waiting for the cd so that I can try it out…

LR