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Advice on HDCAM to Qrez to HDCAM
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[MPE] “NLE can use any data rate – t”
Should be FRAME RATE.
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[MPE] “Nevertheless, as Oliver explained, the codec while being used in the NLE can use any data rate – thus not compatible with DVC Pro HD decks unless converted back to 100 Mb/s @ 60p. “
Unfortunately none of this is an exact science and neither Panasonic nor Apple are really forthcoming with exactly what these codecs do. In a sense your statement is more or less right. If you capture NATIVE DVDProHD via FW and removed the pulldown frames to end up at 23.98, you will not be able to record this back to tape over FW. This is where Kona2 and other such cards come in. The result is that the common path in and out of any NLE is generally a decompressed full-bandwidth signal. If you shot Varicam, are using the DVCProHD codec in post and intend to master back to a deck like the 1200A, you will in effect go through the decode/re-encode (decompress/re-compress) cycle at least 3 times when a capture card is used. If you choose to post uncompressed you still hit the codec twice.
At this point, it’s still way too early to tell whether any of this is really a problem in a practical sense. Especially when people seem to be so giddy about HDV!
Sincerely,
OliverOliver Peters
Post-Production & Interactive Media
Orlando, FL
http://www.oliverpeters.com -
you guys are totally forgetting sales tax!
I think we angled ourselves into a posistion to get a 2.6TB XRAID. That’ll hold enough for the show, plus some overhead. Renting a FCP HD studio for a week isn’t very expensive at all, but I’d rather use that $$ to gear us up than give it to a rental house.
I like the idea of doing the whole things in DVCPROHD and then loading/laying off 10bit HD in smaller chunks. But you would all probably agree it’s better if you can have everything 10 HD digitized. Just in case something goes awry, or you type in the wring insert edit timecode. Or you client misplaces their master you made them.
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xraid is nice–it is my understanding the entire array needs to be filled to handle 10 bit 1080i, however…did something change on that?
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sorry, to clarify!
xraid is nice–it is my understanding the entire array needs to be filled to handle UNCOMPRESSED 10 bit 1080i, however…did something change on that?
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really? i’ve never head that, but that definately something i’ll look into right now.
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[Oliver Peters] “Therefore, the actual data per frame is more than when you capture 23.98 footage with 2-3 pulldown on a 60fps tape (as in the Panasonic formats). The result is better image quality because there is less compression for each and every frame. “
Well… a bit of egg on my face. I did a little checking with folks in the “know” as well of some more of my own testing and I was wrong. It seems that all DV-based codecs, as well as D5, HDCAM and Avid’s DNxHD, work off of a fixed datarate.
It goes like this: Mbps rates are based on the largest frame rate in the group, e.g. 720P would be 59.94/60. 100Mbps is fixed per frame based on 60fps. Therefore, each frame gets the same encoding whether it is 1/60th or 1/24th of a second. To their knowledge no current frame-based codec is optimized for different frame rates.
Thought I should correct my mistatements.
Sincerely,
OliverOliver Peters
Post-Production & Interactive Media
Orlando, FL
http://www.oliverpeters.com -
xserve has two raid controllers and needs all 14 drives to unlock the performance…this is sort of a secret “gotcha”. you will find plenty of info comparing 4 drive, 7 drive and 14 drives of performance on the xserve…
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I doubt that you’ll see any difference between 8-bit and 10-bit uncompressed HD. Remember, you’re going to and from HDCAM, if that’s still the plan. I highly recommend not doing the creative cut in uncompressed. Even with a fully loaded XRaid, uncompressed is pretty slow and unresponsive compared with compressed or SD resolutions. Offline edit in lower res, then conform/online in uncompressed.
Sincerely,
OliverOliver Peters
Post-Production & Interactive Media
Orlando, FL
http://www.oliverpeters.com -
definitely that is the good workflow. i just gave a warning that if you get an xraid that is not fully populated it willnot give peak performance that you see spec’ed everywhere and incase you were doing uncompressed 10 bit work, you don’t want an expensive and non-returnable surprise.
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