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.dv to .mov audio drift issue

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Kurt Outwater
.dv to .mov audio drift issue
on Dec 14, 2011 at 10:09:11 pm

Has anyone noticed when converting .dv to a dv quicktime there is a drift in the audio? The sync is dead on with the .dv and a few frames early progressively getting worse. If I render the .dv audio in FCP the resulting audio file is in sync....in compressor or quicktime or episode i have the drift.

Anybody ever run into this...I'd love to use a batch type program b/c I have a number of files rather than fcp.

Thx


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Dave LaRonde
Re: .dv to .mov audio drift issue
on Dec 14, 2011 at 10:17:45 pm

What's the audio sample rate for all these clips?

I THINK MPEG Streamclip is capable of limited batch processing, which would make it better than FCP and its unrelenting requirement for 48 kHz audio files. I don't know for sure; I've never had to use it for that purpose.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Kurt Outwater
Re: .dv to .mov audio drift issue
on Dec 14, 2011 at 11:00:43 pm

the sample rate for the .dv clips are:

DV 32 kHZ

32 bit floating point


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Dave LaRonde
Re: .dv to .mov audio drift issue
on Dec 14, 2011 at 11:09:10 pm

[Kurt Outwater] "DV 32 kHZ"

...and that's why you should give MPEG Streamclip a shot. It's a free download.

FCP requires the audio sample rate to be 48 kHz. Thus, your clips at 32 kHz fall out of sync.
Now, you COULD change the sample rate for all those clips, but you're trying to avoid dealing with them one at a time.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Kurt Outwater
Re: .dv to .mov audio drift issue
on Dec 14, 2011 at 11:43:39 pm

I've tried 32kHZ out of streamclip with the same results. :(


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Kurt Outwater
Re: .dv to .mov audio drift issue
on Dec 14, 2011 at 11:57:50 pm

I believe this may be my issue:

This FAQ http://www.adamwilt.com/DV-FAQ-tech.html states that consumer DV cameras produce unlocked audio and that any NLE that treats the audio and video as separate tracks (such as QuickTime based products) needs to understand how to re-clock the audio. Apparently FCP does this and it appears that iMovie 09 does not. Can anyone confirm if Final Cut Express 4.0 re-clocks the audio to keep the audio and video in sync?

Are there any programs that reclock audio via batch?


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Rafael Amador
Re: .dv to .mov audio drift issue
on Dec 15, 2011 at 2:39:14 am

Try with MPGSTReamclip, not exporting to QT, but "Save as...QT".
rafael

http://www.nagavideo.com


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Kurt Outwater
Re: .dv to .mov audio drift issue
on Dec 15, 2011 at 6:19:10 am

saving as in streamclip just basically changes the extension. The audio is still DV audio which needs to be rendered.


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Rafael Amador
Re: .dv to .mov audio drift issue
on Dec 15, 2011 at 9:28:33 am

Saving in QT rewraps the file as QT.
Unlocked audio shouldn't be an issue.
The drifting of unlocked audio in a one hour file would be unnoticeable for the human hearing, up to SONY.
The problem with ".dv" (DV stream), is not that treat audio and video as separated tracks (as QT files does), but as separated files packed together.
rafael

http://www.nagavideo.com


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Kurt Outwater
Re: .dv to .mov audio drift issue
on Dec 15, 2011 at 3:37:56 pm

I just find it odd that the .dv file stays in perfect sync while any type of quicktime conversion other than a rewrap causes the drift to the point of it being unacceptable after a two hour capture.


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