converting format for Chroma key Purpose?

[Steve Brame]

I may step on some toes here, but a few years ago, when we started shooting in AVCHD, we were under the same impression. Back then we were having to transcode to an intermediate codec anyway because PPRo choked on AVCHD footage. Thinking as you do, and it would seem to be a logical assumption, we did many tests keying identical footage in both original AVCHD and Cineform 4:2:2. We keyed both with Ultra Key and Keylight. The shots were done in our studio and lit meticulously.

I did some blind testing with a few people, and no one could pick out which was which, they appeared absolutely identical. It should be easy enough for you to perform the same test, just to ease your own mind.

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Steve Brame
creative illusions Productions

[Ryan Holmes]

You’re not gaining quality by transcoding your footage. All your doing is putting your 8-bit 4:2:0 into a different container (8-bit 4:2:2), but your not gaining extra sampling information.

Like Steve says, if you need to transcode because the apps you’re using don’t like that particular codec so be it. But you won’t be gaining any quality by doing so. If it smooths out your workflow I’d say transcode to a standard mezzanine codec (like DNxHD or ProRes). This can be helpful if you need to pass footage off to other apps that may not play well with various codecs or a mixed codec timeline. If not, I think you’re just chewing up time and it won’t make your keying any easier or better.

Ryan Holmes
http://www.ryanholmes.me
@CutColorPost

[Don Cobble]

Thank U

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[Don Cobble]

Thank U Ryan

PC 1
I7 2.8 Ghz 8GB Ram
Win 7 Pro 64bit OS
PNY Quadro K2000
PC 2
I7 3930K 3.2Ghz
32 GB Ram
Win 7 Pro 64bit OS
PNY Quadro 4000

3-4 TB HD
Vegas 10 64bit & Vegas 11 64Bit & Vegas 12 & Adobe Production Premium CS5.5.2 & Avid Media Composer 5.5

Camera
Sony EX1 shoot in 1920×1080 30P

[Tim Kolb]

CineForm would technically be a “10 bit” 4:2:2 container, but I agree with both replies here. Shooting directly to a higher quality format in-camera would make a difference, but converting it after the fact really won’t gain you anything unless (as previously mentioned) you need a different format for your computer to handle the footage as FCP users would do with ProRes, etc…

TimK,
Director, Consultant
Kolb Productions,

Adobe Certified Instructor

[Ryan Holmes]

[Tim Kolb] “CineForm would technically be a “10 bit” 4:2:2 container”

Thanks for the correction Tim. I mistyped. My brain said 10-bit, but my hands wrote 8-bit!

Ryan Holmes
http://www.ryanholmes.me
@CutColorPost

[Tim Kolb]

It was a pretty small thing…but many people do transcode to these formats because they’re 10 bit as well as 4:2:2.

Minutiae aside, as I said, I agreed completely with the -substance- of what you were saying.

TimK,
Director, Consultant
Kolb Productions,

Adobe Certified Instructor