iSight Audio Out of Sync with Video

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Level 1

10 points

iSight Audio Out of Sync with Video

I'm running the firewire iSight camera connected to a Dual G5 Powermac. I'm using the iSight to capture audio and video with Quicktime Pro 7 to make video podcasts. I'm capturing at Native Quality as well as the H.264 settings. I've also tried the same setup on my 17" G4 laptop.

At both settings my Video and Audio are out sync by 5 or 6 frames consistently through clip. I've also tried the same setup with a DV camcorder and the audio is fine.

Is this an inherent problem with the iSight? Is there a fix? Is this something to do with QuickTime 7?

- Steve

Mac OS X (10.4.6)

Posted on Apr 11, 2006 12:27 PM

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Answer 1

EZ Jim

Level 7

22,590 points

Apr 12, 2006 5:03 AM in response to Steve04

Hello, - Steve. QuickTime Pro (and other Apple apps like iMovie that can record video) will sacrifice A/V monitoring stream quality if needed during recording to preserve the AV recording stream quality. This may be what happening if the out-of-sync problem occurs ONLY while you are monitoring the recording in progress.

If your audio is out of sync in the QT file that you have saved and are playing back, try these suggestions and see if any of them resolve your problem:

• Increase the light level on your video subject. As explained in Improving Your iSight's Picture, iSight reduces its frame rate in low light to preserve image quality. DV camcorders do NOT change their DV video frame rate, even in low light.

• Consider the suggestions in Mac OS X 10.4 Help: My Mac runs slowly. In addition to CPU capacity, you can check available Disk Space and System Memory with your Mac's "Activity Monitor."

• Be sure your Mac OS X maintenance is up to date, especially permissions, chrons, and disk "free" space.

• Eliminate Possible hardware or software conflicts.

• Do not use an external disk to capture video from your iSight. Capture on your startup disk instead. If desired, transfer the QT files to your external drive after they are saved.

• If you upgraded to 10.4.6 by using your Mac's Software Update..., consider applying the 10.4.6 Combo Updater using a technique like the one suggested in How I Update My Mac OS X.

That is all the ideas I have. If you do not get the answers you need here, try posting in the QuickTime Discussions area.

Please let us know what resolves your problem.

Cheers,
Jim

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Answer 2

Steve04 Author

Level 1

10 points

Apr 13, 2006 2:06 PM in response to EZ Jim

Thanks Jim, this is indeed after it has been saved to a QT. I've opened it up in Final Cut Pro to look at the Audio Waveforms and video. I try not to trust my eyes and ears during playback.

It is hard to believe that I can be suffering a performance issue, since I'm running a recently purchased Powermac 2.5 ghz with 2 gigs or memory. I'm saving to the boot drive. There are no other usb devices connected. I'm using video quality lighting (we're the video production dept. for our Univ.). We have plenty of disc space and a fresh load set. Running 10.3.9

Same thing happens when connected to my G4 laptop with different and same cables.

Still working on it.

- Steve

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Answer 3

EZ Jim

Level 7

22,590 points

Apr 14, 2006 9:29 AM in response to Steve04

Interesting info, - Steve. You might also find some helpful ideas at FCP Discussions.

Will watch for your update...
Jim

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Answer 4

setomi

Level 1

0 points

Jun 13, 2006 10:52 AM in response to Steve04

I have the same problem also on my brand new 15" MacBook Pro. While browsing the forums and the net. I appears a lot of people (everybody?) is having this problem with Quicktime7.

I tried using the built-in camera as well as external camcorder. Still, after a few minutes, the audio gets out of sync. This is a simple as a setup as possible. All updates installed. There must be a flaw with live video encoding.

Currently the only workaround I have was to record to tape. Then import to iMovie. Then export movie. We should have to do all these steps.

Hope someone comes up with an answer soon.

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Answer 5

Steve04 Author

Level 1

10 points

Jun 13, 2006 1:05 PM in response to setomi

After all my testing, I believe it to be the iSight itself. Maybe it is something to do with how it encodes the audio and video for web chatting so it can preserve better quality audio while dropping frames. I noticed that on various computers such as my Laptop and the Dual G5, the frame rate would change over time, always being less on my laptop. On the new MacBooks, the frame rate for the built in cam also varied for example.

I ended up installing an older Panasonic EZ20 that does not ever power down into standby mode ever. It is a workhorse DV camera. The big benefit here is that the video is now saved as DV video, 5 minutes per gigabyte where as the iSight was doing uncompressed video that did not easily import in to Final Cut Pro.

As for capturing with QT 7, I See no fault with the software and have used it to capture several hours at a time via DV camera.

Sorry if that does not help.

- Steve

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