Does codec or color space matters in live green screen?

shemster

Member
If I'm doing a live streaming show with greenscreen using Tricaster, does the codec matters (XAVC-I or XAVC-L) or 422/420 or the camera matters when I'm not even recording?
 
Well.. what you are seeing is still the camera sensors interpretation of the scene. So yes it matters. 4:2:0 will cause you problems. Not sure about xavc i vs l

Edit: a quick read tells me xavc L isnt good for greenscreen. Partly because you are working against a non existing background and then because L is 4:2:0
 
Last edited:
What is coming out of the back of the camera matters, but Im not sure that is connected to the recording (to card) codec.. read the manual?
 
Generally speaking, what comes out of the camera live should have nothing to do with the internal recording codec, but check the specs of what the camera is spitting out of the SDI(or HDMI).
 
Sorry.. true... I immediately thought OP was using a FS7 or similar due to the two codecs he mentioned. Which camera are you using OP?
 
Generally speaking, what comes out of the camera live should have nothing to do with the internal recording codec, but check the specs of what the camera is spitting out of the SDI(or HDMI).

I'm looking at getting Sony HXR-NX5R for live green screen works. Checked the manual but there is no mention of 8 or 10 bits, 422 or 420 output through SDI. It only mention "BNC type (x1), SD/HD/3G(Level-B) selectable SMTPE 259M/292M/424M/425M standards".
 
You might want to talk to Sony to get the exact specs of the output of that camera, I don't see it listed anywhere. There are no hard and fast rules about a camera's internal codecs, bit rate and color space versus video outs, they all seem different. FWIW, I shoot a lot of green screen. Totally possible to shoot decent looking green screen with a 4:2:0 8-bit output but you have to nail the green screen, subject lighting, contrast, WB, green screen illum ratio versus subject, etc. And even when you do, you will not have fine control and latitude over spill suppression, relighting, and pushing keys. 4:2:2 and 10-bit are much better for all of that and 4:4:4 and or uncompressed even better. Who is your audience and how visually sophisticated is the project? Do the keys need to look perfect or just good enough? How good are you and or your gaffer at lighting green screen? Are you going for photorealistic to try to make your keys appear real? Will the BGs be plates shot with? Stock footage? Stills? Motion graphics? Virtual sets? You're dealing with a style of shooting that has a lot of variables and can be shot and composited in a lot of different styles.

If image quality is important, you should consider using a better camera, a sub $3k Sony isn't bad and may be good enough for your needs but it may not give you an optimal image, depending on what you are trying to achieve and how picky you and or your clients are.
 
You might want to talk to Sony to get the exact specs of the output of that camera, I don't see it listed anywhere. There are no hard and fast rules about a camera's internal codecs, bit rate and color space versus video outs, they all seem different. FWIW, I shoot a lot of green screen. Totally possible to shoot decent looking green screen with a 4:2:0 8-bit output but you have to nail the green screen, subject lighting, contrast, WB, green screen illum ratio versus subject, etc. And even when you do, you will not have fine control and latitude over spill suppression, relighting, and pushing keys. 4:2:2 and 10-bit are much better for all of that and 4:4:4 and or uncompressed even better. Who is your audience and how visually sophisticated is the project? Do the keys need to look perfect or just good enough? How good are you and or your gaffer at lighting green screen? Are you going for photorealistic to try to make your keys appear real? Will the BGs be plates shot with? Stock footage? Stills? Motion graphics? Virtual sets? You're dealing with a style of shooting that has a lot of variables and can be shot and composited in a lot of different styles.

If image quality is important, you should consider using a better camera, a sub $3k Sony isn't bad and may be good enough for your needs but it may not give you an optimal image, depending on what you are trying to achieve and how picky you and or your clients are.

I'll be doing virtual set for live streaming. Audience and client will not be picky and I guess most cam will be good enough.
 
The bit only affects the tonality of the colors. Mostly something you's notice in the gradation from light to dark or a blue sky from deep blue to light blue.
So it could affect the look of you talent and grading options, but shouldnt affect your greenscreen too much
 
The bit only affects the tonality of the colors. Mostly something you's notice in the gradation from light to dark or a blue sky from deep blue to light blue.
So it could affect the look of you talent and grading options, but shouldnt affect your greenscreen too much

Good to hear that! I'm more concerned about removing the green screen cleanly.
 
But... if you have a chance...please do a test first. If your job is important and the road to succes is determined by the functionality of the gear, then you need to make sure it works before going into the fray. These comments are first and foremost theoretical :eek: I've had some stupid greenscreen experiences in the beginning, not taking chances anymore :D
The most pro shops here will let me try the gear... a demo cam or something like that, before actually purchasing it, if I have any doubts.
 
No good news I think.

Afaik keying green is very testing of a codec.

Doing it live you camera may however not be the weak link in the chain.

Indeed - test.
 
Back
Top