HDV Greenscreen
by Elisheba Monte
on
Jun 25, 2008 at 3:36:36 pm
OK - Maybe I've missed this because this seems like it would be a basic question but I'm not finding much information about shooting greenscreen with HDV cameras. Let me preface this by saying that I realize that HDV is NOT the best format for shooting green/blue screen but going true HD at this point is probably not an option.
I would think that the better the resolution, the better the key would be but even that does not seem to be clear cut. The Canon xl-h1 would be great but you can only get the highest resolution by bypassing the on board tape and going straight to an external source. The Panasonic HVX theoretically should be good (with true HD to the P2 cards and 4:2:2 color space,) but I've heard of problems with a "halo" around the subject when keyed. I've also been looking at the Sony z7u but I can't seem to find the resolution when recording to the CF card.
Can anyone make sense of this or point me in the right direction for more info?
[Elisheba Monte]"The Panasonic HVX theoretically should be good (with true HD to the P2 cards and 4:2:2 color space,) but I've heard of problems with a "halo" around the subject when keyed." If someone is getting a halo around thier images with the HVX200 4:2:2 color space, it is more about the keying software and not the HVX/DVCPRO HD. I have seen singular blond hars in the wind keyed with no problem and definitely no halo.
Thanks,
Jan
Jan Crittenden Livingston
Product Manager, HPX500, HVX200, DVX100
Panasonic Broadcast & TV Systems
Re: HDV Greenscreen by Michael Palmer on Jun 25, 2008 at 4:14:19 pm
You are correct HDV is not anyones first choice for green screen work, however if you properly light your subject and separate it from the green screen enough to stop the green reflection bouncing back on the subject you can have good results. HDV is not the best solution but it does work. If you could live capture from either the analogue or digital signal you would be better off. If you plan on doing a substantial amount of green screen work and your camera has either an HD-SDI or HDMI port you may consider the new Nano Flash recorder coming out soon from Convergent Design.
http://www.convergent-design.com/ This unit will allow you to record at a much lower compression that goes way beyond HDV from the manufacturer, you can start with 50Mbps 4:2:2, 100Mbps 4:2:2 ALL I-frame, or 160 Mbps 4:2:2 all I-frame right to a Quick Time .mov on inexpensive Compact Flash media.
Re: HDV Greenscreen by Tim Kolb on Jun 25, 2008 at 6:41:32 pm
[Elisheba Monte]"The Panasonic HVX theoretically should be good (with true HD to the P2 cards and 4:2:2 color space,) but I've heard of problems with a "halo" around the subject when keyed. I've also been looking at the Sony z7u but I can't seem to find the resolution when recording to the CF card."
As much as the "true HD" thing is sales rhetoric and has no bearing on anything...
I've keyed many HVX200 shots with no more trouble than anything else. Shooting to key is primarily about lighting and exposure...and of course a competent post person using a reasonably good tool. I've seen no halo around a subject, though someone who decided to backlight with magenta when keying against green would definitely create an edge that would be desperately difficult to spill suppress by most conventional methods contrary to popular belief.
The Sony HDV camera lays the same thing on the Flash card as it does on the tape...4:2:0 MPEG 1440x1080. THAT said...I've also greenscreen keyed HDV and it isn't as different as many would have you believe. Each format makes some compromises as they are both HD cameras available at a very modest cost.
Re: HDV Greenscreen by Danny Hays on Jun 25, 2008 at 10:42:51 pm
Hello, I have a Sony HDV camera and can get great results. I have used Adobe Ultra and Keylight in After Effects with superb results. I agree with Tim on the lighting being a major factor. I think people that use a magenta backlight when keying with a green screen may not have a decent key software package, one without spill suppression like Vegas. I am not a big Adobe fan but their SC3 premium and master collection packages I believe come with After Effects and Keylight 1.2, Ultra and On Location. On location is a great tool to set up your camera and green screen lighting and a great direct to disk app too. Ultra also has a live preview feature that allows you to see your talent in front of the background you will use with very little latency. This allows you to accurately set the camera angle, distance, and lighting to match the background. All very important when making a convincing key. The live preview only works with DV so you’ll have to set your camera temp. to DV out while setting it all up. I also turn my camera 90 deg on the tripod when shooting a person or subject taller than wide. This gives you 1440 line of res from top to bottom instead of wasting it with unused video on the sides. You can turn it back up right in the key software. Both Ultra and Keylight have great spill suppression so backlight but not magenta. Ultra is a standalone app and is not your standard timeline nle and takes practice timing the foreground to the background but can key with very poorly lit and wrinkled green screens. Keylight is a plug-in and works in the timeline and is way more flexible than ultra because of that fact. I also convert my HDV m2t files to Cineform avi progressive when using Ultra as it has a hard time with m2t files. Hope this helps.
Re: HDV Greenscreen by Elisheba Monte on Jun 25, 2008 at 11:18:01 pm
Interesting - I've always heard that backlighting with magenta helps the key but never tried it myself - maybe that's a good thing... It always seemed like it would create more problems than it solved.
I have Keylight with After Effects but the last time I worked with green screen I used Primatte RT that comes with Motion - worked like a charm, I've never had anything that keyed so cleanly and quickly (of course, that was with a beta source and an decently lit screen.) Obviously I haven't tried it with HD yet.
BTW Danny, which Sony camera do you have?
Thanks everyone for the info - helped clear up a lot.
Re: HDV Greenscreen by Danny Hays on Jun 26, 2008 at 3:02:42 am
Just the HVR-A1U. It has a great picture as long as I have alot of light. Not great under low light though. Fairly inexpensive. I mainly shoot in front of a green screen so I always use alot of light. Danny
