Processing Power

L

lacuna

Well-known member
Barry, you've mentioned before that HDV is actually more processor intensive than DVCProHD because frames are not captured as discrete units, but in groups of pictures.

What I'm wondering is, given that @720p HDV uses a GOP of just 6 (as opposed to 12-15@1080i on the Z1), will this level things out a bit? Will HDV@720p still require more grunt than DVCProHD?

And (I've read around this topic before but got lost in the numbers), in the hands of the new HDV friendly crop of NLEs such as FCP5, is HDV a lossless codec? I mean, after I import footage into the NLE, perform some basic cuts (without any fancy rendering), will the material I export lose any quality in the process? (assuming I export it as HDV)

Hey, this question isn't addressed exclusively to Barry, but to anyone who has the patience to explain, thanks a bunch! I know DVCProHD is a superior format - what I'd like to know is, once I have recorded footage on a DV tape on HDV, is the hit already taken, or am I going to lose more in the NLE.
 
I think the best response I can say is -- go look at Adam Wilt's article in DV magazine. He's done some extensive testing of HDV and today's crop of NLE's, and came to some intriguing conclusions.
 
I'm just fearing there's no truly native HDV NLE, they all recompress what doesn't need to be recompressed (unlike DV NLE's).
 
According to Adam, the difference between one-generation down recompression and native is so stark, you'd want to recompress the whole thing anyway. Otherwise your footage would look something like old Super 8 tape splices -- looking pretty good until you hit a transition, where everything becomes blurry and muddy, and then as soon as the transition's over it starts looking good again...

Apparently the HDV implementation of MPEG-2 can split GOP's and close them early and start new GOP's at transition boundaries, but it doesn't look very good to do it. If you're doing cuts-only editing, on GOP boundaries, it's perfectly acceptable (like DV is). But if you're changing the duration of the program and cutting in the middle of GOP's, you will have to recompress segments (if you're going back out to HDV). If you're not going back out to HDV (like, for example, you're rendering your final in WMV9 format) then there's no issue, it'll work like native. But if you're intending to go back out to HDV, you've got trouble. MPEG-2 is a delivery codec, not an editing codec, and you can't freely edit like you can in DV without it showing some serious degradation.
 
Barry,

I wrote this on anothe thread but Edition and FCP have I frame timelines which only needs a GOP reorder, not recompress. That is the difference between native HVD editing which belong to Pinnacle and FCP right now. We'll see what Avid does if the buyout occurs and they get the Pinnacle technology.

It takes a horse of a computer to edit HDV multilayer. Twin HT intel such as the HP XW8200 PCIexpress are required on the PC side. I think G5 is required on the Mac side.

best,
 
What's the benifit of editing HDV natively? Although I have not used PPro with AspectHD for any of my own projects I have seen it used on a few projects that were output to D5 and it looked great and was as easy as editing DVCPro HD (100Mb's/Sec)

It was a fairly expensive Boxx system but the quality looked good. So why not get out of HDV at the same time you ingest?
 
Chuck,

Native editing is the same as no recompress so the max quality is retained (in the non edited areas). In the case of Edition you can do RT effects and then publish right back to tape or send up to a live feed without any recompress or GOP reorder. It is all realtime. This means alot to online editing. Offline editing is another story altogether. I made a short video displaying how it works in Edition for Barry Green a few months ago. The main thing to know about native editing is that you can do effects, cuts, transitions etc without a render.

Take care...
 
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