12-bit Audio issue

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Alexi102000 Author

Level 1

145 points

12-bit Audio issue

Hey guys, long story short, I lent a canon xl1 to a coworker and he ended up recording 12-bit audio onto miniDV instead of 16-bit. Now the tapes are in my hands and I'm trying to transfer them to the Mac.

I can't seem to change any of the capture presets to match the source tape (12-bit/32khz I believe). Does anyone know where to find this option?

Thanks,
Alexi

PowerPC G5, Mac OS X (10.4.8)

Posted on Jul 23, 2007 11:14 AM

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Answer 1

ADCNR_Tim

Level 2

460 points

Jul 23, 2007 11:32 AM in response to Alexi102000

Go to: Final Cut Pro > Audio/Video Settings..., click the Capture Presets tab, click DV NTSC 48kHz and hit the Duplicate... button to make a copy. Under Quicktime Audio Settings, change the format to 32.000 kHz 16-bit 2-chan to match the sample rate of the audio on tape. The bit depth doesn't have to match (16-bit is better than 12 anyway). You'll also have to adjust your sequence settings in a similar way.

tim

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Answer 2

Alexi102000 Author

Level 1

145 points

Jul 23, 2007 1:34 PM in response to ADCNR_Tim

Thanks Tim, that seems to have fixed most of my problems. After capturing, I've noticed that the audio starts out in sync, but gradually gets out of sync. This might be another problem in itself though.

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Answer 3

ADCNR_Tim

Level 2

460 points

Jul 23, 2007 1:48 PM in response to Alexi102000

Glad you got it.

I've noticed that the audio starts out in sync, but gradually gets out of sync.

Is your sequence set to 32.000 kHz also?

tim

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Answer 4

Alexi102000 Author

Level 1

145 points

Jul 23, 2007 2:33 PM in response to ADCNR_Tim

It seems the original capture's audio is out of snyc (I haven't placed it on a sequence yet).

I'm going to try to get the audio back in sync using a sequence that matches the source clip (32khz/16-bit). It will probably be difficult though since it seems the audio gradually gets out of sync (as opposed to the video stuttering, then the audio getting out of sync).

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Answer 5

Alexi102000 Author

Level 1

145 points

Jul 23, 2007 2:47 PM in response to Alexi102000

Err...it seems the audio is in sync on the original source tape, so something must be going on during the capturing process.

In any event, I'll mark this thread as solved, play around with a bit, and make another thread if I can't figure it out. Thanks again for your help Tim!

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Answer 6

ADCNR_Tim

Level 2

460 points

Jul 23, 2007 2:49 PM in response to Alexi102000

It could be that the deficiencies of DV format video are more evident with 32k audio -- meaning: the DV format records audio unlocked from the video, using a different way of deriving its clock sync. Professional formats like DVCAM and DVCPRO 25 build upon the DV format, including features such as locked audio, where the audio derives its sync from the video and is locked to the video where it will not drift as it can with DV. I suppose that it may be more noticable at 32k than 48k.

Try shorter clips to reduce/eliminate the drift (if that is indeed the problem).

tim

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Answer 7

ADCNR_Tim

Level 2

460 points

Jul 23, 2007 2:52 PM in response to ADCNR_Tim

Oh, and if you can capture with a capture card using component or SDI, that'll solve the sync issue, aaannnddd...you can work at 48k!

tim

No prob

Message was edited by: ADCNR_Tim

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