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How is pulldown audio recorded on video tape?

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Steve MacMillan
How is pulldown audio recorded on video tape?
on Mar 25, 2011 at 7:31:22 am

I understand audio pulldown very well as it relates to sync.

What I don't understand is what happens to pulldown audio at 47952 when its dubbed to a video deck that wants to see 48k? This would be typical with synced sound from a telecine session to a SD offline tape.

Is the dub performed digitally? Does SDI work differently than an AES input? If so does the deck digitally re-sample it back to its internal recording rate of 48000? Does it stay 47952? Or do you typically transfer from a pulled down audio playback onto the SD tape via an analog input, so that the audio is resampled at 48k thru the analog converters?

Steve


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Peter Groom
Re: How is pulldown audio recorded on video tape?
on Mar 25, 2011 at 10:17:07 am

Its a damn good question, that ill need to look into to answer, but for the moment id suggest an analogue pass wont kill anyone.
I think any vtr will struggle with sdi as the audio will be embedded and embedded at the wrong rate. im NOt aware that VTRs have any sr adjustment internally.
Cheers
Peter

Post Production Dubbing Mixer


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Steve MacMillan
Re: How is pulldown audio recorded on video tape?
on Mar 26, 2011 at 12:52:30 am

Thanks,

Apparently there is a lot of on set recording at 48048 (with or without the 48k metadata flag) so that when the film is pulled down, the audio ends up at 48k.

Then there is a high quality sample rate conversion down to 48k when the project is pulled-up to 24fps for film out.

I'm still unclear what happens when you sync sound in telecine from a 48k audio recording and print to video tape with a pull-down.

Steve


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