FCPX–Audio Loses Sync when capturing long segments

[Bill Davis]

[Jeff Marier] “does FCPX have a similar issue?”

No. It doen’t.

Video to audio sync issues are typically caused by one of two things – non-standard sample rate issues embedded in the audio files, or system performance issues with the ingesting system’s processor being bogged down such that it can’t simultaneously work with the video and audio streams in lockstep and has to handle them separately.

Go back to your audio source and check out it’s specifications. If necessary, transcode the audio to something standard like 16 bit 48Khz and see if that solves the problem.

If that doesn’t solve the issues, you might just be using too underpowered a system for working with the specific types of video and audio files you’re working with.

Good luck.

“Before speaking out ask yourself whether your words are true, whether they are respectful and whether they are needed in our civil discussions.”-Justice O’Connor

[Charlie Austin]

Don’t know if this helps, but standard 12-bit audio on DV has a 32 kHz sample rate. This may be the problem, but I don’t know where in X you’d compensate for this. I Know in 7 you’d just modify the capture setting but in X? Anyone? I doubt you need a new computer. lol 🙂

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~”It is a poor craftsman who blames his tools.”~

[Walt Kerr]

Using a brand new iMac (3.4GHz i7 processor) with 20GB RAM and I cannot get a reliably sync’ed capture using FCPX. Most of my tape captures are 45 minutes in length but audio sync goes out almost immediately in the capture. This problem is intermittent for me, sometimes there is sync, sometimes not. I’ve quit using FCPX for capture and paid $30 for Quicktime 7 Pro and I’m getting solid captures now. I’m capturing from miniDV tape with 48K 16 bit audio, same as my FCPX project settings. Seems many other are having this problem. Hopefully there will be a fix soon. Besides QT7 Pro, are there any other good capture utilities out there with decent VCR deck control for the Mac?

[T. Payton]

Humm. I”ve not seeing those issues. But I’m in the habit of create a camera archive from HDV and MiniDV. Have you tried that, perhaps it is some issue with capturing direct.

I’m sure you already have, but make sure you report it to Apple.

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T. Payton
OneCreative, Albuquerque

[Bill Davis]

Traditionally, this problem comes up when the camera op THINKS that they have the camera switched to one set of values – but it’s actually recording to another.

Try this.

Capture a very short clip of video and audio. A few seconds is enough. Put the clip on your desktop where you can find it and download the simple, free MediaInfo app.

Drop the clip on it and it will tell you the actual stats used for encoding the video and audio.

If the audio (OR the video for that matter) is at a weird frame rate or encoding standard it will tell you for sure.

In the brave new world of digital video where clips have so many possible attributes from codecs to wrappers to sample rates – it’s an important first step to verify what you’ve got rather than just assuming that because the camera is supposed to record in a format that it actually is.

Hope this helps.

“Before speaking out ask yourself whether your words are true, whether they are respectful and whether they are needed in our civil discussions.”-Justice O’Connor

[Walt Kerr]

Thanks Bill. I gave MediaInfo app a try and the audio indicates it is 48k at 16 bits. Tried capturing the same clip again one day later and had no audio slip at all. Double-checked the recording deck and it is set to record audio at 48K 16 bits (only other choice is 32K at 12 bit). Guess I’m still mystified. We’ve moved almost totally to Canon 7D/Zoom shoots with no sync issues but I have this weekly videotape to deal with. Guess it’s time to look at another recording medium. Thanks again.

[Bill Davis]

[Walt Kerr] “We’ve moved almost totally to Canon 7D/Zoom shoots with no sync issues but I have this weekly videotape to deal with. Guess it’s time to look at another recording medium. Thanks again.”

Just another thought…

You know that when you import content into X, depending on how you have your software setup, many times “background rendering” is on. If that’s the case, it’s quite possible that during pauses, X will switch your computers “attention” to rendering files in the background. And sometimes that means that your real time performance will take a hit.

If you’re finding stuff out of sync during one session, but the problem disappears a day or so later – it MIGHT be that the software is working extra hard processing stuff that’s not fully rendered – and when it’s finally done with it’s background stuff, it will work better.

Just a thought.

“Before speaking out ask yourself whether your words are true, whether they are respectful and whether they are needed in our civil discussions.”-Justice O’Connor