Inconsistent bad ProRes outputs (video and audio out of sync)

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Inconsistent bad ProRes outputs (video and audio out of sync)

Running batch conversions of H.264 5D/7D footage to ProRes 422 LT results in a large number of files with out of sync audio and video. I opened the out of sync clips in Quicktime Pro, looked at the properties and saw that the video and audio tracks had different durations. One example is video duration: 46.96. Audio duration: 46.79. All of the out of sync clips have this problem with the video/audio duration and it's always video that's longer than audio. The source H.264 files have the same duration for audio and video tracks.

I tried running my transcodes in Squeeze 9 Pro, Squeeze 8.5 Pro, and MPEG Streamclip. Streamclip produced more correct files than Squeeze, but there were still some that were wrong. I'm going to be ProResing hundreds of clips and I can't check them individually.

I also tried running the transcodes on another computer with Squeeze 8.5 Pro and Streamclip and the outputs were fine. I think the problem is related to my computer somehow (corrupt or incomplete codecs, a hardware problem, etc.).

Mac Pro Mid 2012

12-core 2.4 GHz Intel Xeon | 48 GB 1333 MHz DDR3 ECC | ATI Radeon HD 5770 | 500 GB SSD

PCI: Sonnet Tempo SATA E4P | CalDigit Super Speed PCI Express USB 3.0

Mac Pro, OS X Mountain Lion (10.8.4)

Posted on Jul 16, 2013 1:56 PM

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Answer 1

Russ H

Level 7

22,432 points

Jul 16, 2013 3:05 PM in response to Uncle_shank

How was the audio recorded?

Russ

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Answer 2

Uncle_shank Author

Level 1

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Jul 17, 2013 7:02 AM in response to Russ H

A 788 multi-track was sending a feed to the cameras' receivers, which I've never had a problem with in the past. The audio is 48 kHz 16-bit stereo.

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Answer 3

Russ H

Level 7

22,432 points

Jul 17, 2013 7:10 AM in response to Uncle_shank

First thing that comes to mind is that - for whatever reason – the recorder clock has lost accuracy.

There's a roduct called syc-n-link which is well-regarded. It's not cheap though and I just checked and don't see a trial. Might want to contact them; they're pretty responsive, I've found.

Russ

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Answer 4

Uncle_shank Author

Level 1

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Jul 17, 2013 8:00 AM in response to Russ H

I don't think the problem is with the recorder, it's how this particular computer is botching ProRes. All of my source H.264 files are correct, have the same video and audio duration and picture is in sync with audio.

On this particular machine (that I purchased mainly to tackle these large transcoding batches), it generates ProRes outputs where the video and audio tracks differ, thus sending it out of sync. I've tried re-ProResing the source from these bad outputs and sometimes they turn out fine. There doesn't seem to be much rhyme or reason, it just very inconsistently generates bad ProRes outputs in multiple encoding programs that I've never had issues with before.

So the problem is not with the source, but with some software or hardware problem on my new MacPro regarding ProRes.

Also worth noting, when I first got this machine I tried converting ProRes videos to MainConcept H.264 MP4 and it created outputs that lagged and had wildly erratic framerates. At the time I thought the issue was with Squeeze 9 Pro, but now I think my computer caused this.

More information:

I'm up-to-date with my ProApps, and I have Final Cut Pro 7.0.3 and Quicktime 7 Pro 7.6.6 (1709).

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