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Audio Metadata In DPX files?


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#1 Michael Emmett

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Posted 22 January 2007 - 02:43 PM

I think this is the right forum for this question...

Does anybody know if you can seperate audio once it's been embedded in a DPX file? Let's say you recorded 8 channels originally. Then in post can you seperate your audio and will it still be in 8 channels or does it get compressed into 2 channels?
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#2 Keith Mottram

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Posted 23 January 2007 - 05:48 AM

as dpx files are single frames, can you tell me how the audio could possibly be imbedded?

keith
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#3 Michael Emmett

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Posted 23 January 2007 - 03:27 PM

as dpx files are single frames, can you tell me how the audio could possibly be imbedded?

keith


A quote from Stwto's DFR whitepaper:

"Digital audio is [also] treated as a metadata file and carried with frame information. Eight channels of uncompressed AES/ESU 24 bit 96Khz audio are recorded."

If the audio isn't imbedded then maybe it's linked with the timecode and stored as a seperate file... Having never actually worked with HD before I can't say for sure. I'm just doing research.

Edited by Michael Emmett, 23 January 2007 - 03:30 PM.

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#4 Phil Rhodes

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Posted 23 January 2007 - 03:52 PM

Hi,

You can embed audio in DPX frames. The only thing I know of that supports such a thing is the S2 recorder; when I used it, there was nothing in the post path (including a Clipster, fer chrissake) that would read this extension to the DPX format, and we ended up doing timecode-locked dual system sound. It's rare.

Phil
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#5 Michael Emmett

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Posted 23 January 2007 - 08:17 PM

Hi,

You can embed audio in DPX frames. The only thing I know of that supports such a thing is the S2 recorder; when I used it, there was nothing in the post path (including a Clipster, fer chrissake) that would read this extension to the DPX format, and we ended up doing timecode-locked dual system sound. It's rare.

Phil


The Xena capture card says that is can capture this audio through dual HD SDI. I'm guessing the problem you had was a software problem. The software couldn't read the audio.

I hope there is software somewhere out there that can deal with this problem. It would be a shame if there isn't any. It would save everyone from having to do dual system sound.
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#6 Phil Rhodes

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Posted 23 January 2007 - 09:35 PM

Hi,

You don't have to do dual system sound; just don't record fricken DPX.

"We must have DPX," they cry. Then they write an awful lot of software to do timestamping, audio embedding, bin and shot management, all of which has to touch thousands of files per take, and then another bunch of software to unwind it all when you come to read the data. All of this and more you get for free with AVIs and Quicktime movies, which are not meaningfully harder to read than a DPX sequence.

Working with a file-per-frame format has one (1), single, solitary, lone advantage - you can archive it and easily extract just part of a shot, and with hard disks being as cheap as they are now, that's a pretty feeble excuse.

Phil
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#7 Michael Emmett

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Posted 23 January 2007 - 09:50 PM

Hi,

You don't have to do dual system sound; just don't record fricken DPX.


Right... But do HD cinema cameras output to AVI?
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