Green Screen Dancing Edge Pixels (After Effects CS6)

[Matt Dodds]

[Mark]“I can’t really as I’m “archaically” still using CS6.

Here’s tiny utility though you might want to check out. It installs as a windows Explorer Right Mouse Click menu item when you’ve any sort of media file selected. It’ll give you a LOT of info on the files make-up such as codec, frame rate, bit rate, etc. Very worthwhile having to diagnose with.”

I completely understand. While I was in school, we AE CS6 for my Digital Effects class, but after that class, they changed it to that current years CC, so I just used CS6 due to funds! For video editing, we used Avid Media Composer, so I have been on a different level on everything or a little behind when it comes to programs!

I just downloaded it and I will use it for now on. We never really learned codecs, we more focused on camera angles, editing, and ISO/F-stop/Shutter Speed!

[Steve Bentley]

Hey Matt,
It looks like the forum didn’t update properly so I missed your long post with my comments in quotes – let me answer those shortly.

[Mark Whitney]

[Matt Dodds] “”If you zoom in on your footage to this level and step through it frame by frame (no key or effects) you can see the edge of the hairline boiling and little areas of distortion going on where chunks of hair literally move over 16 pixels for a few frames and then move back or sections get averaged to keep the bandwidth. This may be function of the camera or the codec, I’m not sure, but this is also going on at the edge of the hair so you are keying a moving target. It’s almost has a shower glass effect.”

Is there a way to alleviate this problem, if any?”

Quite simple: As we’ve mentioned, just get a bit better exposure on your subject (add some backlight) and more uniform process screen exposure. From the sample you posted, it uses a chroma subsampling of 4:2:0. Common, looks fine in most cases, but doesn’t leave much wiggle room when doing keying work.

To fix this shot: No quick/easy fix really. Least painful is to reshoot if possible after you get your set-up dialed in and those ARE easy fixes.

[Steve Bentley]

Here’s a lengthy response to your question where you quoted my answers:

I think all the issues are due to the codec and the camera.

Some cameras just don’t produce a clean image. The camera makers can hide a number of sins, including a blocky image, by adding noise and this may have been done on that camera. There’s a reason a RED camera is $40k and Arri’s go for more than $100k (and that’s before lenses and doodads!) and prosumer cameras are only in the $1500 t0 $5k range.
Shoot with the best camera you can (we’ll even rent a special camera just on the green screen days while the rest of the production is shot on something else less costly)

When we do green screen we are so picky that we ask for a digital feed out of the camera, live on set- that feed is usually uncompressed, but even if it isn’t, its always miles better than what goes to the tape. Very few cameras record uncompressed to tape. 4K files are so massive that you wouldn’t get too much footage on a single tape – you would be pining for the good old says when film reels were only ten or twenty minutes long.
That feed goes right to our capture card which is capturing in an “uncompressed” lossless codec in 10 bits. And that goes right to our hard drive array. This way we can also do a test comp on the set to make sure the key is pullable. There is just no comparison between any version of H264 and this kind of file. H264 was made as a final delivery codec and not one for doing effects with. So much of the information you need for effects is long gone on a H264 compress even when its done way up at 40mb/s (twice blue ray). Even Apple’s ProRes is way better than H264 for effects work. Do a a little research on what 4:2:2 or 4:4:4 means (and all the other combinations) with regard to color space in codecs and cameras. Its shocking how little color information is needed to convince the human eye they are seeing reality. Keying software is not that easily fooled.

But you can’t always get to the set or they don’t want to “waste the time” (more on this later). And you don’t always want to rent a deck to capture the footage with. So if you can have someone digitize the footage you should ask for a high color space format. Like EXR or ACES or RAW (if you can handle this one) or Cineon. And you will get stills, not movies. Sometimes you can get the camera’s proprietary format, like on a RED. What ever it is, get as close to uncompressed as you can with the largest color space (8 bit is just so last year!). But make sure you have have a codec that can read that format. (in this instance codec doesn’t mean compression; more so its compatible and readable by AE). We like EXR – AE, Photoshop and most 3D software reads it out of the box, its 16 bit or 32 bit, can hold an alpha and multipass rendering.

The DPX format (and I’ll be branded a heretic here by some for saying this) seems to have a different flavor depending on the camera. The big cams that use it (like Arri) use it well but some of the prosumer cams use it too and have mangled it. It can be excellent but it can also be terrible. Ask for a set of test frames. Watch what happens when you play it – view zoomed in at 800%.

As for the ideal color for the screen it really depends on the camera, subject matter and what screen material you can get. If you get a pipe frame for your screen, you can stretch it across the frame to get most of the wrinkles out. There’s no point ironing the whole thing because only parts of it are in the shot or its so far back its out of focus. We take a steamer to set for pesky wrinkles that are showing. Under the strain of the frame those wrinkles take one look at the steamer and straighten up right quick. The frame also means you don’t have to tack the screen up – just attach the frame to two C stands.

If you light the screen with green gelled lights (barn door those lights so none of that falls on the talent) you can pick your gels to tweak the color of the screen. You have to balance these lights with the ones that light the talent which also fall on the screen. We light the screen first so we can start with that evenly lit. The minimum we shoot for is 20 feet between screen and talent and another 20 feet to the camera. A short lens used in green screen screams “Effects shot!” and never looks real. A good distance from your screen also means the bounced spill light from it will be minimized on your talent’s edges – which is the all important keying area.

We get the camera info before hand and then look at the color sensitivity of the CCD (or film stock if you are going that way). Look at where the green color arc peaks or where the green arc is the farthest from the red arc and choose a color for the screen or the gels that gets you closest to that frequency of light. There are color meters out there that can measure this when you look at the screen through them.

But all of that is probably moot on a shoestring budget. That image I sent you is a very nice color of green as a rule of thumb – kind of dayglow lime green. The one you used, while functional, is a little too forest green or emerald green (its got too much blue in it). The idea here is to pick a green that is not “contaminated” by either of the other two primary colors – add some red and the screen is more yellow green, add too much blue and you get your color. You want that screen only showing up in the green record of the file. You can still key with your color, or any color for that matter (ironically the best screen color is red, just not for people) but the closer you can get to the magic color the easier the trickier stuff is – fine hair, veils, glass, water, reflective stuff.

A 20 foot by 20 foot screen (called a “20by” written “20x” in the industry if you are renting) is pretty much the smallest you want. By the time you get the screen back twenty feet from the talent (a minimum you should shoot for) a 20by just barely covers a person head to toe. Renters also have standard frames that fit this size. From there they go 20’x40′ and 40×40. And they do go bigger for outdoor landscape masking screens. You can also paint a cyc in a studio. Green screen paint is crazy expensive (because its hitting the magic color) but you can get Home Depot to match the color you want – matte always. Take in a bit of green screen gaffer tape for them to match.

Lighting is important – try and get a smooth and even a lighting pattern across the screen – use a spot meter to measure side to side and up and down and in the center. Again you can key without this step but often you have to pull multiple keys for different sections of the screen.

Codecs – H264 is a miracle and has single handedly made the internet a viable delivery mechanism for movies (in 1991 I said this was something that could never happen because of film resolution and internet bandwidth – but then I’m in good company: Richard Edlund said the same about digitizing film into a computer the year before, and Bill Gates said 640kb was all you would ever need for RAM – the moral? Never say “never”, or try your hand at futurecasting). But H264 is not a good effects format for your fx source. Sure its lightweight to send around over the internet but you want every drop of data you can get from the shoot and you don’t want the codec fudging the truth just to get the file size down.
Blackmagic Design has an excellent codec that bridges the gap between a lightweight compressed (but noisy) codec like H254 and the near perfect but massive records of a RAW or EXR. And as luck would have it they also make capture cards. You don’t need the capture card to work with BMD’s format but you do need one to play the format real-time. They also make an excellent and reasonably priced cinema camera (whether they have any in stock is quite another matter)

I know this all sounds like a lot to hoist onto a director because the effects guys are already the thorn in his/her side slowing down principle photography. But getting the details right will make your composites go so much smoother and you will have more latitude when something was done incorrectly, or there is too much motion blur in the footage to pull a key, or the tracking markers aren’t showing, or or, or….
Keep in mind too directors are terrified of the effects side of things. So while you are a time delay distraction with all your requirements, they know that it’s in their best interest to give you what you need to work with or their post budget will soar.

[Steve Bentley]

I went searching for camera footage in H264 and couldn’t find any that were compressed as low as what you uploaded (even my gopro has a higher bit rate that this) Are you sure you have camera footage and not someone’s recompress?
Take a look at the footage in the link below – its H264 (albeit at 10 times the bit rate of yours) and it keys with one click. Its clean enough for a good key, keeping the whips of hair at the edges.
While you do have issues with wrinkles in the screen there has to be a cleaner record of this footage somewhere. And that would help you immensely.
12287_171003d0172k.mp4.zip

[Mark Whitney]

[Steve Bentley] “While you do have issues with wrinkles in the screen there has to be a cleaner record of this footage somewhere. And that would help you immensely.”

Good catch Steve. Here’s a report of this footage vs. Matt’s using the MediaInfo utility:

Matt’s “Bad Greenscreen:
General
Complete name : D:\AE CS6 Projects\From 2018\Misc Sources\12279_shortgreenscreen.mp4
Format : MPEG-4
Codec ID : M4V (M4V /mp42/isom)
File size : 3.63 MiB
Duration : 6 s 590 ms
Overall bit rate mode : Variable
Overall bit rate : 4 626 kb/s
Encoded date : UTC 2018-03-21 21:30:25
Tagged date : UTC 2018-03-21 21:30:25
TIM : 00:00:00:00
TSC : 24000
TSZ : 1001

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Baseline@L4
Format settings : 2 Ref Frames
Format settings, CABAC : No
Format settings, RefFrames : 2 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 6 s 590 ms
Bit rate : 4 455 kb/s
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 23.976 (24000/1001) FPS
Standard : NTSC
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.090
Stream size : 3.50 MiB (96%)
Language : English
Encoded date : UTC 2018-03-21 21:30:25
Tagged date : UTC 2018-03-21 21:30:25
Color range : Limited

Steves “Good” Greenscreen:
General
Complete name : D:\Ttemp\Toss\12287_171003d0172k.mp4
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42 (mp42/mp41)
File size : 87.2 MiB
Duration : 22 s 880 ms
Overall bit rate : 32.0 Mb/s
Encoded date : UTC 2018-02-08 16:16:18
Tagged date : UTC 2018-02-08 16:16:19
TIM : 00:15:18:06
TSC : 25
TSZ : 1

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Main@L4.2
Format settings : CABAC / 2 Ref Frames
Format settings, CABAC : Yes
Format settings, RefFrames : 2 frames
Format settings, GOP : M=4, N=25
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 22 s 880 ms
Bit rate : 32.0 Mb/s
Width : 2 048 pixels
Height : 1 080 pixels
Display aspect ratio : 1.896
Frame rate mode : Constant
Frame rate : 25.000 FPS
Standard : PAL
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.578
Stream size : 87.2 MiB (100%)
Language : English
Encoded date : UTC 2018-02-08 16:16:18
Tagged date : UTC 2018-02-08 16:16:18
Color range : Limited
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709
================================================

So ya, either his got re-encoded OR there’s something amiss with the camera settings. Note the Bits/Pixel Frame values. Just nothing there.

[Matt Dodds]

Hey Steve,

In school, we used a Blackmagic camera in our RAW class and it worked out great, I’m just not the best when it comes to RAW footage and color correcting. I don’t have a budget when it comes to renting things and we used a 60D in school (our lower classes), so I got that one because it worked well. I was thinking about getting a 80D because I do have people in my state, that are videographers, that suggested that.

This is the info from MediaInfo about the footage from my camera:

Complete name: E:\DCIM\100CANON\MVI_1882.MOV
Format: MPEG-4
Format profile: QuickTime
Codec ID: qt 2007.09 (qt /CAEP)
File size: 364 MiB
Duration: 1 min 4 s
Overall bit rate: 47.5 Mb/s
Encoded date : UTC 2018-03-14 13:50:56
Tagged date : UTC 2018-03-14 13:50:56

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Baseline@L5
Format settings : 1 Ref Frames
Format settings, CABAC : No
Format settings, RefFrames : 1 frame
Format settings, GOP : M=1, N=12
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 1 min 4 s
Bit rate : 46.0 Mb/s
Width : 1 920 pixels
Height : 1 080 pixels
Original height : 1 088 pixels
Display aspect ratio : 16:9
Original display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 23.976 (24000/1001) FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.925
Stream size : 352 MiB (97%)
Language : English
Encoded date : UTC 2018-03-14 13:50:56
Tagged date : UTC 2018-03-14 13:50:56
Color range : Full
Color primaries : BT.709
Transfer characteristics : BT.709

I exported the 6 sec clip from Premiere in H.264/DSLR, so that is one reason why it might not be working on your end. It looks like my codec that it is using is AVC, which might be less compression?

The thing is I use all of my own equipment, so I don’t rent or borrow anything. I do need to look at the footage zoomed in on my camera, as it always adds grain and it’s not flattering.

For the screen, I thought about that, but it is difficult to get them and set them up everytime I shoot, so I normally thumbtack it up, which I understand isn’t the best option. I did order a blue-screen, since I did get some advice, outside of this forum, that a blue screen might be a better option, but everything you talked about, it probably wont work with my camera and it’s settings.

Where can I get green gelled lights and do you have a good lighting kit? I bought a photography lighting kit with fluorescent light bulbs, so that is my only thing I have. It just sucks that my camera and lens doesn’t pick up enough light to do much with it. The next time I record my next veterinarian, I will have them farther away from the green screen, I just know that I will not able to to use the footage I have too much, since the deed is done. I am just happy I recorded the footage without the green screen!

Since I am an one-man team, I am not able to do everything like that by myself, especially with no budget, besides what comes out of my pocket. I liked the dayglow lime green color. Again, I got this green muslin from a photography kit, so it was what came with it. I will try to find a dayglow lime green color muslin for my next shoots.

Again, I am limited on what I can do at the place I work, so I will have to try to find a 20by or 20x.

Lighting has been one of my biggest weaknesses. I want to get some LED lights that I can change from Tungsten to Daylight, as I think that would fit the feel of my work, but I just don’t have the best lighting set up. I did try to light the green screen more, since I knew that would be my biggest issue, but it looks like I need way more lights than I have!

We were taught that H.264 was something that was really great, and it is, but not for what I am doing! We even used a 60D and H.264 format and pulled a good key (one of the only times we used green screen work). It can be done, but it’s very rare and I understand what you are saying.

What kind of capture card are you thinking/using?

I took a digital effects class in college and it was fun, but something that I never wanted to do full time/as my career, but green screen work sounded fun, but after this experience, I know I have way more to learn about stuff like this and it’s nice. Like stated above, I am an one-man team, so I am the director, producer, editor, renderer, and poster, so I do it all. I do get some guidance from my supervisor, as to what I should be recording, but nobody knows about film/video/recording, so that is why I came to this blog. I did research this topic before I came here and learned some stuff, but nothing compared to my dilemma, so I do appreciate your help and with your words of encouragement and guidance, I will try to work it out. My next plans of action is to figure out what codecs I can record in, on my 60D, the distance from the background and the screen/frame, getting a new lime green screen, and maybe getting a better camera body, since that might be some of my issue there (due to not picking up enough light).

[Matt Dodds]

Hey Mark,

I did post my MediaInfo on the footage off my SD card and the bit/frame rate is showing at .925 and not at the .578 of my exported footage from Premiere. I am not sure really how to change the bit/frame rate at the settings. I did look at all the menus, but nothing is showing about that!

Thanks!

[Matt Dodds]

Hey Steve,

Sorry I misread your info, I didn’t see the .090. Dang… that is low. Again, I am not sure what I need to do to change that!

[Mark Whitney]

Not sure either if it’s a camera setting. But if it was just that your footage got reencoded somewhere along the line, hopefully you can simply track that down.