Derrick_SA
Veteran
Hi there,
So this means with 4:2:2, that this camera should be great for Greenscreen work right?
Thanks,
Derrick
So this means with 4:2:2, that this camera should be great for Greenscreen work right?
Thanks,
Derrick
Is HVX true 4:2:2
- Thread starter smelni
- Start date
Barry_Green
Moderator
There are many factors that go into getting great greenscreen work, of course. With all other things being equal, yes 4:2:2 should deliver twice as much color resolution (and therefore much more accurate keying) than 4:1:1 or 4:2:0.
Another aspect of successful greenscreening is compression noise. All other things being equal, the less-compressed (and therefore less noisy) image will deliver superior keying results. In DVCPRO-HD mode, the footage is actually more compressed than in DV, but still way less compressed than HDV. But in DVCPRO50 mode, the compression is exceptionally mild.
So yes, DVCPRO50 mode should deliver keying that's comparable to Digital Betacam. In DVCPRO-HD mode, the compression noise will be more noticeable, but it'll still have substantially more color resolution, plus there will never be any motion artifacting.
So, to say in one word what it just took me several paragraphs to blather on about, "YES" -- the HVX should be the finest green-screen camera anywhere near its price range.
Another aspect of successful greenscreening is compression noise. All other things being equal, the less-compressed (and therefore less noisy) image will deliver superior keying results. In DVCPRO-HD mode, the footage is actually more compressed than in DV, but still way less compressed than HDV. But in DVCPRO50 mode, the compression is exceptionally mild.
So yes, DVCPRO50 mode should deliver keying that's comparable to Digital Betacam. In DVCPRO-HD mode, the compression noise will be more noticeable, but it'll still have substantially more color resolution, plus there will never be any motion artifacting.
So, to say in one word what it just took me several paragraphs to blather on about, "YES" -- the HVX should be the finest green-screen camera anywhere near its price range.
stephenlnoe
Well-known member
I'd like to see the sequence if you come across it and have the notion to put up a link.Graeme_Nattress said:
Anyway, you may remember reading my thoughts on the matter (HDV edit's, FX and color correction) over on Cow a couple of months back. All editing/FX/ColorCorrection is done uncompressed and the limitation I've run into has not been the transport stream but instead has been gradient banding caused by an 8 bit color pallette. Even when working with 16bit subpixel routines it's not the same as a 10 bit source to start with (as you state) and anyone would have to be careful with gradients and HDV or DVCProHD, particularly using a secondary color corrector. Selectively isolating any primary or secondary colors to boost saturation will cause DCT to show itself. Brightening the overall image gain, gamma and black level luminance has not been a problem at all nor has gain, gamma and black level RGB adjustments caused many problems.
Barry_Green
Moderator
Stephen, you've asked for examples of when the JVC codec chokes... I was cleaning up my hard disk and came across the Charles Papert/Nate Weaver mini35 footage we shot in L.A. and found a wild doozy of an HD100 motion artifact. The full .m2t that it's in is 115 megabytes or so, so I just extracted the little bit that shows massive double-image shadowing into a .WMV at maximum bitrate to preserve the effect as best as possible. Looks like Nate was swinging the camera around for some reason, and the buildings show some major artifacting and macroblocking and banding. as well as a bit of split-screen at the end.
This clip had the mini35 attached, and I would suspect that the grain of the mini35 probably pushed the codec over the edge; I doubt that this would have happened with the stock lens attached, at least not to this degree.
http://www.icexpo.com/HD100/HD100-weirdness.wmv
If you want the full 115mb .m2t I can send it to you, but I wouldn't want to post it publicly as 115mb files would choke my bandwidth allocation in no time...
This clip had the mini35 attached, and I would suspect that the grain of the mini35 probably pushed the codec over the edge; I doubt that this would have happened with the stock lens attached, at least not to this degree.
http://www.icexpo.com/HD100/HD100-weirdness.wmv
If you want the full 115mb .m2t I can send it to you, but I wouldn't want to post it publicly as 115mb files would choke my bandwidth allocation in no time...
Barry_Green
Moderator
Okay, rooting around some more in the files, it looks like they all have this same weirdness going on. Here's a still extraction of the girl as she walks by:
Check out the massive double-image shadow behind her arm (and speaking of which, where *is* her arm?) and the shadowy purse, the banding and macroblocking and posterization... No matter how you slice it, I think everyone would agree that a frame-based codec like DVCPRO-HD would have done extremely better with that shot.
Nate had said that the mini35 caused a lot of artifacting in his music video, and MacGregor just posted saying that FX1+mini35 is way too artifacty, so I think we can safely say that mini35 + HDV = too much for the codec to handle.
The full .m2t on this one isn't too big, it's about 32mb.
http://www.icexpo.com/HD100/HD100-Night-Take-01_6.m2t
Check out the massive double-image shadow behind her arm (and speaking of which, where *is* her arm?) and the shadowy purse, the banding and macroblocking and posterization... No matter how you slice it, I think everyone would agree that a frame-based codec like DVCPRO-HD would have done extremely better with that shot.
Nate had said that the mini35 caused a lot of artifacting in his music video, and MacGregor just posted saying that FX1+mini35 is way too artifacty, so I think we can safely say that mini35 + HDV = too much for the codec to handle.
The full .m2t on this one isn't too big, it's about 32mb.
http://www.icexpo.com/HD100/HD100-Night-Take-01_6.m2t
Barry_Green
Moderator
All right, one last one, but in motion I think this is the worst one:
The double-image shadow that follows her hair and her right hand are just extraordinary. Watch it in motion, it's hard to believe:
http://www.icexpo.com/HD100/HD100-Night2.wmv
Full of split-screen too.
Without the mini35, the HD100 has always seemed to be to be quite robust. But now, having seen the footage played back, I'd say that it is absolutely useless with the mini35 (or any of the cheap variants as well). No way could someone trust this. Frame-based codec is the only way to go.
Of course, we didn't see any of this when shooting the footage; shooting it live it all looked gorgeous. This is a prime example of why the HDV aspect of "what you see ain't what you get" drives me batty -- you can't see this stuff happening in the viewfinder or on the monitor; it's only after you record it and play it back that you get to see what HDV has done to your footage.
It's weird -- this shadow seems to primarily affect the red channel; you can see a lot of red shadowing all over the place on anything that moves, her hair gives off a red glow as it bounces and her hands have a weird red tracking shadow.
The double-image shadow that follows her hair and her right hand are just extraordinary. Watch it in motion, it's hard to believe:
http://www.icexpo.com/HD100/HD100-Night2.wmv
Full of split-screen too.
Without the mini35, the HD100 has always seemed to be to be quite robust. But now, having seen the footage played back, I'd say that it is absolutely useless with the mini35 (or any of the cheap variants as well). No way could someone trust this. Frame-based codec is the only way to go.
Of course, we didn't see any of this when shooting the footage; shooting it live it all looked gorgeous. This is a prime example of why the HDV aspect of "what you see ain't what you get" drives me batty -- you can't see this stuff happening in the viewfinder or on the monitor; it's only after you record it and play it back that you get to see what HDV has done to your footage.
It's weird -- this shadow seems to primarily affect the red channel; you can see a lot of red shadowing all over the place on anything that moves, her hair gives off a red glow as it bounces and her hands have a weird red tracking shadow.
stephenlnoe
Well-known member
There is a setting in the camera that forces the red channel called WhitePaint <R> which will enhance the warm effect after white balance. Maybe your group changed that setting? or the setting was changed initially?Barry_Green said:
As I recall, your shoot was just before or just after the camera's release. Since then the split screen has been addressed pretty well and I'm almost sure the SSE was under the radar when your group was shooting. Now, SSE can be adjusted by a qualified tech if needed.
The camera move, hmnnn.... I'll try and simulate that (again) with one of ours. I've tried a lot of camera moves and the encoder holds true on everything I've tried. Your shot of the halo is only the second time I've seen that effect in a frame. Was that halo in successive frames or on that single frame? I don't know but it's rare and I have not come across it in my own footage.
I'm just not seeing these types of things in my footage. As I wrote above, the biggest problem I have is banding caused by gradients that are beyond the 8 bit pallette. DVCProHD will not be immune to that either. I'll be putting more m2t's up on that other thread.
take care amigo...
Barry_Green
Moderator
We definitely didn't go painting the image much at all. Mainly we adjusted the gamma and boosed the color gain, but we didn't go in the whitepaint settings at all.
As far as SSE, this was prior to the formal launch of the HD100 in the US, although it had been out in other countries for a while before we got to use it for this shoot.
As for what's going on in the footage, I think it's just total codec breakdown, and I think it was the mini35 that did this to the footage. The spinning sea of grain particles seems to have pushed the codec over the edge. I don't think you'll likely encounter these same effects without the mini35.
I posted frame-for-frame .WMV extracts of the pertinent sections of the M2T's, and I posted one of the M2T's. The halos are tracking everything and last for a long time.
Again, I don't think the regular HD100 would exhibit as much of this, although I did see a bit of the shadowing effect in Nate's downtown m2t's. But I do think that this makes the HD100 (and probably all HDV cameras) useless for mini35 / micro35 work.
As far as SSE, this was prior to the formal launch of the HD100 in the US, although it had been out in other countries for a while before we got to use it for this shoot.
As for what's going on in the footage, I think it's just total codec breakdown, and I think it was the mini35 that did this to the footage. The spinning sea of grain particles seems to have pushed the codec over the edge. I don't think you'll likely encounter these same effects without the mini35.
I posted frame-for-frame .WMV extracts of the pertinent sections of the M2T's, and I posted one of the M2T's. The halos are tracking everything and last for a long time.
Again, I don't think the regular HD100 would exhibit as much of this, although I did see a bit of the shadowing effect in Nate's downtown m2t's. But I do think that this makes the HD100 (and probably all HDV cameras) useless for mini35 / micro35 work.