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DVCPRO HD over Firewire


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#1 Alexis Hanawalt

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Posted 29 November 2005 - 04:23 PM

I'm going to be digitizing some 24P Varicam footage via firewire into G5's running FCP 5 for a narrative feature which will probably be blown up to 35mm film.

Every single source I have says that DVCPRO HD footage captured via firewire suffers no generation loss whatsoever - except for Goodman's Guide, which has a brief paragraph stating that the image is compressed and sustains a loss in the high end. The guide then states that sending a cuts-only edit back through firewire to the deck results in a tape copy with 100% of the data of the original tape masters. I don't understand this, and I can't find any information that corroborates this.

I called Panasonic and the tech was stumped. He'd never heard that there was any loss. I've emailed the author of the guide for elaboration, but haven't heard back yet.

Does anyone here have any DEFINITIVE information regarding this issue? It could be of critical importance when we do the blow up.

-Alex H.
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#2 ChristianK

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Posted 29 November 2005 - 04:45 PM

I'm going to be digitizing some 24P Varicam footage via firewire into G5's running FCP 5 for a narrative feature which will probably be blown up to 35mm film.

Every single source I have says that DVCPRO HD footage captured via firewire suffers no generation loss whatsoever - except for Goodman's Guide, which has a brief paragraph stating that the image is compressed and sustains a loss in the high end. The guide then states that sending a cuts-only edit back through firewire to the deck results in a tape copy with 100% of the data of the original tape masters. I don't understand this, and I can't find any information that corroborates this.

I called Panasonic and the tech was stumped. He'd never heard that there was any loss. I've emailed the author of the guide for elaboration, but haven't heard back yet.

Does anyone here have any DEFINITIVE information regarding this issue? It could be of critical importance when we do the blow up.

-Alex H.


I have no definitive information but I've been through several DVCPROHD jobs. From the qoute you gave, I think what Goodman is refering to is the compression done by the camera capture which is pretty severe. After that, anything done via firewire will be lossless
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#3 Alexis Hanawalt

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Posted 29 November 2005 - 07:20 PM

I have no definitive information but I've been through several DVCPROHD jobs. From the qoute you gave, I think what Goodman is refering to is the compression done by the camera capture which is pretty severe. After that, anything done via firewire will be lossless


That may be... But this paragraph was really dedicated to the principle of digitizing via firewire. I mean, I know that firewire is inherently jumbling up 1's and 0's to a pretty great extent so what ends up at one end is more a reassembled 100% re-creation of what was at the other end than an identical duplicate... but for all intents and purposes, there should be no loss... right?
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#4 Peter J DeCrescenzo

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Posted 29 November 2005 - 07:54 PM

Just an FYI: I apologize because I know almost nothing about DVCPRO-HD, so I'm unsure if the following info is related.

Graham Nattress has written in-depth about differences between capturing _DV_ via SDI vs. Firewire. Apparently, capturing various forms of DV via SDI provides superior results compared to Firewire captures. If DVCPRO-HD is closely related to other forms of DV, then perhaps this info will be useful:
http://www.kenstone....n_nattress.html

All the best,

- Peter DeCrescenzo
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#5 ChristianK

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Posted 30 November 2005 - 12:10 AM

Correct. Firewire is a direct transfer of information. I'm an editor and just finished a pilot where we chose a firewire capture from the 1200A deck directly into FCP. We chose that over using a Kona card because taking it over SDI would have been decompressing it from it's native codec (DVCPRO).

Also, you might have checked creativecow.net mostly editors and engineers, they might give you a much more straightforeward answer than I can. They'll also be able to help through editorial if you haven't encountered all the problems with Panasonics decks yet.



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#6 Phil Rhodes

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Posted 30 November 2005 - 07:05 AM

Hi,

> Apparently, capturing various forms of DV via SDI provides superior results compared to Firewire captures.

What I read him as saying is that the SDI output on the DSR-1800 interpolates the UV channels. Great, fantastic, it's been clear for a while that interpolated chroma can look better, and key better.

Phil
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#7 Christopher Bell

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Posted 30 November 2005 - 09:03 PM

Firewire editing offers great value for the money. You can edit in HD, and deliver your 720p project for film out directly from the 1200a deck at 1080 24p! Final Cut Pro 5 is required for the best picture quality. Apple made substantial improvements to how it handles the DVCPRO HD codec. I color correct and use dissolves with confidence now. There are always limits to everything, but as long as you don't push color correction too far it should work great.

Remember, firewire editing offers great value... it may not necessarly be the best work flow for all projects.

Chris Bell
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#8 Tjerker

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Posted 20 December 2005 - 05:27 AM

Capturing your video via Firewire is, indeed, losless. As long as you do not compress or decompress your video, it stays the same as captured on tape. EVERYtime you alter the video (dissolves, color correction: the works) you'll go through a decompression - compression cycle, and you'll lose quality. That's the reason they mention having a cuts only transfer - then you don't lose anything.

If you're planning on heavy duty editing, you could capture via SDI and then stay uncompressed in the rest of the workflow. Even better is to capture straight to disk while shooting - but that's an other story.

Edited by Tjerker, 20 December 2005 - 05:29 AM.

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#9 Brian Wells

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Posted 20 December 2005 - 07:09 AM

Final Cut Pro 5 is required for the best picture quality. Apple made substantial improvements to how it handles the DVCPRO HD codec.

Could you go into a little more detail? Many years ago I was hired to edit some downconverted VariCam tapes. I always thought the footage looked more "stroby" than film. Just last week I went back and looked at the tapes and was surprised that upon close inspection the tapes had an odd pulldown... Appears to be a 2:2:2:4 ! No wonder it looked, "stroby" to me! My question is where in the chain could the D.P. (who provided the BetaSP and MiniDV tapes) have made this mistake? I am not sure how he downconverted the footage, as this was early 2003. He does own a 1200A Deck, FCP, etc. But, how could this have gotten messed up so badly? This was on an 18K music video.
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