DVCpro HD dubs
by Nathan Daniel
on
Apr 8, 2008 at 6:23:15 pm
How do you create exact copies of DVCpro HD tapes without loss of quality and keeping exact timecode? I have heard that you can either use two decks or capture from firewire into final cut and then export back to a new tape. What equipment/software do I need?
I have the latest version of Final Cut and a Quad Core Intel 2.8Ghz Mac.
Re: DVCpro HD dubs by walter biscardi on Apr 8, 2008 at 8:34:41 pm
[Nathan Daniel]"What decks, cables, etc., do you need?"
We have two Panasonic 1400's that we tie together via HD-SDI cables for video and just standard BNC for the TC.
You just can't use the first generation DVCPro HD decks with tapes that have been shot with the newer generation cameras. 1200A and 1400 are the two most popular VTR's out there.
Walter Biscardi, Jr.
Biscardi Creative Media HD and SD Production for Broadcast and Independent Productions.
Re: DVCpro HD dubs by Logan Kelsey on Apr 8, 2008 at 11:49:17 pm
Be sure that you to get the proper frame-rate flags (UB) on the tapes when you make dubs. I got bit by this. I had some dubs made by a 3rd party, and the tapes didn't the proper flags and that was a problem for all my off speed stuff, etc... Here is part of a response from Gary Adcock:
Re: DVCpro HD dubs by walter biscardi on Apr 9, 2008 at 12:32:37 pm
[Sean ONeil]"SDI dubbing is lossy on the 1200, the 1400, and the 1800. You need to use Firewire for lossless cloning."
That's what I thought too until I checked with my Panasonic reps. It's a clean digital pipe either way. We've checked our dubs against scopes and the clone is a perfect digital replica of the original.
Walter Biscardi, Jr.
Biscardi Creative Media HD and SD Production for Broadcast and Independent Productions.
Re: DVCpro HD dubs by gary adcock on Apr 9, 2008 at 2:10:09 pm
One is a dub and one is a clone....
With FW connection the 1200 and 1400 decks have the ability to CLONE the data from tape to tape when coping. (a clone is a digital copy, and since the data being passed back and forth is just the digital 1's and 0's)
Using HDSDI is a making a Dub (since the video is passing out over Baseband and then back to tape)
Walter is correct in that the loss of detail in the Dubbed tape should be under a .1 % IRE variance according to Panasonic's info. (1/10 of 1 percent)
gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows
Inside look at the IoHD
Re: DVCpro HD dubs by Sean ONeil on Apr 9, 2008 at 5:50:42 pm
That's cool, but the term "lossless" has a very specific meaning, and even a .01% variance doesn't cut it. I'd also argue that looking at scopes will not detect some aspects of loss especially if the chroma and luma levels stay exactly the same. Using the difference filter in AE or Photoshop is probably the best way to test if something is truly lossless.
It's fair to say that SDI dubbing is "virtually lossless" and that in a real life workflow it's just as good. I'm not criticizing the practice at all. I'm just saying it isn't lossless. I do all my work in ProRes now which isn't lossless either.
Re: DVCpro HD dubs by Nathan Daniel on Apr 9, 2008 at 2:10:16 pm
Thanks for all your help. I guess the only clarification that I need now is whether I should hook two 1200As together with firewire or a 1200a to a 1200a or 1700 over BNC. Is the setup process for firewire dubbing much easier then the BNC process?
Re: DVCpro HD dubs by Sean ONeil on Apr 9, 2008 at 5:40:42 pm
[Nathan Daniel]"Thanks for all your help. I guess the only clarification that I need now is whether I should hook two 1200As together with firewire or a 1200a to a 1200a or 1700 over BNC. Is the setup process for firewire dubbing much easier then the BNC process?"
Again, firewire is lossless. BNC is not (you need two 1700 decks to do lossless with BNC).
Walter and Gary have pointed out that SDI to SDI with these decks are virtually lossless as far as the scope readouts are concerned. But firewire is a digital data copy, not a dub. So you can't go wrong with firewire. I'm guessing they're on the same equipment rack, so there's no reason to use BNC anyways.
