HDV is color sampled at 4:2:0, which isn't great for chromakey work, but a heck of a lot better than the 4:1:1 of DV. Converting to an intermediate format won't gain you anything in term of chromakey quality since the color has already been sampled at 4:2:0 when it got recorded to tape. If you happen to be shooting with an HDV camera which has HDMI out, like the V1u, then you could use the Blackmagic Intensity card to capture live. What come out of the HDMI port on the camera (when used live and not recorded to tape) is uncompressed 1920x1080 4:2:2. This will provide the source for some very good looking chromakeys. The Intensity can record the 1920x1080 HD as either uncompressed YUV at 120 megabytes/second(!) or intraframe 4:2:2 MJPEG which still looks very good but has a considerably lower data rate.

(When you record to HDV tape, the uncompressed 1920x1080 4:2:2 signal from the camera gets resized to 1440x1080, downsampled to 4:2:0 and compressed to 25Mbit MPEG2.)

I don't do any HD yet but I do a lot of green screen. I use Zenote Deartifact to smooth the jagged edges and it gives me a much better key. I use 4:1:1 as I edit NTSC DV. They also provide 4:2:2 and 4:2:0

thanks bob / jc,

so i must have misread what i thought i'd read or, more likely, skimmed and not absorbed the facts....

while i was waiting for a reply i tried a test with a very short clip.

a. sony 10bit

b. sony 50i

c. m2t

to be honest, they looked identical, the key was exceptionally clean, and all of them stuttered along in preview (only to be expected on my e6600). putting them out to m2t and playing back was no problem - with them all looking very presentable (so much so i couldn't tell them apart). so it looks like i'll simply work with the m2t's.

i know the distrib. will be web based, but they want hd versions to use at conferences etc.,

again, thanks

leslie

I just find anything chroma keyed straight looks bad and then you blur makes a bad job worse

So when you use the chroma key, key out the green then copy same clip under without croma key make parent on top multiply mask now it looks real
And set your params from there you color corect your second layer Because green light refracts and you want to replace that with other tones

Especially when working with smoke and hairy spiders and stuff like that where you want to keep the detail so now you have a premultiplied mask

What do the other guys think?

When I did Multiply the image was dark. I changed to "Darken" and the image was then ok. Not sure what I did different.

Oops sorry I left out add mask generator on top clip

Just try this out

If you have a clip of fire on black background
Double up the clip

On top layer add mask generator . Multiply mask . Set your parameters make that parent
You obviously must have a pic underneath that.

Now compare the results to a clip where you have keyed out the back

The premultiplied mask is more realistic than the keyed mask so for keyed shots I just stick to a matt black screen
For example you have a hairy spider [ I did this for bird gardens] shoot on a matt black back

Even the small thin hairs are retained after the channel is multiplied
Wheras the shots that I did on a green screen were crap even if you added fx second color corrector saturate greens

I was wondwering what the other guys were doing

Rory