| When and where does the compression happen?
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 | When and where does the compression happen?
by Christoph Baaden on Nov 22, 2004 at 8:47:43 pm |
Hello Experts,
this is probably a newbie question - I am trying to understand the compression difference between capturing DVCProHD with the DVCPro codec via Firewire vs. capturing it uncompressed SDI (which is an option with the Kona 2, correct?).
When you shoot DVCProHD with a Varicam, doesn't get the footage automatically compressed on tape? Capturing on the 1200A deck via Firewire gives me a 1:1 clone, including the compression that has happened while recording it? FCP just doesn't need to recompress, correct?
But even If I capture via SDI to 10bit uncompressed, I still get the compression that has already happened on the tape when it was recorded. And compression can't be undone, correct? Or is there a way to "decompress" the footage via SDI (which would go against all the things I learned about compression so far).
So there would be no difference capturing it native DVCPro vs. SDI- both ways I would capture already compressed footage? The quality of the footage should be the same if I have a cuts-only project??
Christoph
PS:
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• | | | |  | Re: When and where does the compression happen?
by Chris Bell on Nov 22, 2004 at 9:12:24 pm |
The 1200a transcodes footage from the Varicam (960x720) to to any format you like: 720p,1080i,1080@24fps,480,PAL.
Transcode quality is subjective... I find the 1200a does a fantastic job via HD-SDI. SD-SDI also looks quite good. Firewire is great for low-cost editing, but you are working with compressed data which has its limitations.
Chris Bell
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• | | | | | Re: When and where does the compression happen?
by Christoph Baaden on Nov 22, 2004 at 9:51:17 pm |
Chris,
that goes to core of my question. How is it possible that capture over firewire is compressed data (sure, DVCPro is natively compressed), but the HD-SDI route supposedly isn't. The compression happened when the Varicam recorded the data on tape. Firewire or HD-SDI, both capture compressed media. So why do HD-SDI? It doesn't decompress, does it?
Am I wrong?
Christoph
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• | | | |  | Re: When and where does the compression happen?
by Noah Kadner on Nov 23, 2004 at 12:45:50 am |
Nope but you will avoid further compression. Editing DVCPROHD means anything you do to the footage other than straight cuts will be recompressed. It holds up well but as Chris implies- it's subjective. There's always a trade-off between compression, cost and quality.
Noah
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• | | | | | Re: When and where does the compression happen?
by Chris Bell on Nov 23, 2004 at 3:28:23 am |
Panasonic designed the DVCPRO HD codec to be trancoded (960x720 to 1280x720 or 1440x1080 to 1920x1080). There is no loss in the process, rather it is part of the design.
Chris Bell
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