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Canon Vixia HF G30 camcorder - compression - color sampling 4:2:0 - Is a clean Chroma key possible?

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Michael Arnes
Canon Vixia HF G30 camcorder - compression - color sampling 4:2:0 - Is a clean Chroma key possible?
on Dec 11, 2015 at 7:16:56 pm
Last Edited By Michael Arnes on Dec 11, 2015 at 8:20:16 pm

Hi everyone,

I have a simple question which I'll ask right away for the sake of simplicity. And then I'll explain my situation, details, etc.

Question: Assuming a good lighting setup, can I possibly get a good chroma key result with my Canon Vixia HF G30 camcorder?

Here is the situation:

I'm a beginner DIY video maker. I recently bought a Canon Vixia HF G30 camcorder, primarily to do some green screen footage. I shoot in AVCHD, at 24 Mbps LPCM, at 23.976 fps. The camcorder also has an available setting of 24 Mbps (with no LPCM), but I don't know the difference. Like I said, I'm new at this. Anyway, I've been using LPCM setting, for whatever reason.

I light my green screen (muslin 10 x 20) with 2 DIY "Kino Flo" lights (each with 4 fluorescent bulbs, 4 foot long, Daylight 6500K). I use the Chroma Keyer App on my ipad and it shows a very evenly lit screen. I had the subject stand approx 6 or 7 feet away from green screen (that's all the room allowed for).

I then lit the subject with a key light, fill light and hair light (using softboxes, etc)

I then convert AVCHD (.mts) footage to ProRes 422. Then I import ProRes 422 footage into After Effects CS5.5.

However, I've been having a really hard time getting a clean key. I've watched a lot of tutorials on the do's and don'ts of Chroma key (eg. making sure to get even lighting on the green screen, having your subject stand at a decent distance from the screen, etc) I have also learned about Keylight 1.2, and the fact that I shouldn't expect a great key in just 1 pass (so I learned about multi-layers with different settings on Keylight, etc). Despite all of this, I am still having a very hard time getting a good key. The main problem I'm seeing is that when I render the final result, there is always a really bad flickering outline around the subject. No matter how much I shrink or expand my matte, it just doesn't go away. Even if I expand the matte to the point of making the subject 30% thinner (just for an extreme test), the flicker remains.

I was wondering whether my camera is the problem? Maybe it's the compression? The color sampling specs? I just called Canon USA and after a lot of waiting on hold, the rep told me that the color sampling on this camcorder is 4:2:0. Not what I wanted to hear.

Should I just give up trying with this camera? Or is there a possible way to still get a clean chroma key with it?

I would appreciate any info. Thanks.


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Dave LaRonde
Re: Canon Vixia HF G30 camcorder - compression - color sampling 4:2:0 - Is a clean Chroma key possible?
on Dec 12, 2015 at 12:36:33 am

Does that camera record at 23.976, or is it 29.97? I'm wondering if it adds 3:2 pulldown, which would account in part for screwy-looking edges. If you're going to shoot at 24p, You've got to remove the pulldown -- if it exists.

If you have the option to shoot at 720 and not 1080, it might help matters. It doesn't have messy fields -- you can only shoot complete frames at 720. And it OUGHT to be able to do 23.976; I don't know for a fact that it can.

Also, Kaylight likes a chroma key background that's a little darker than some other keyers.

You should be able to pull an okay key. Not a great key, just okay. That's 4-2-0 for you.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Michael Arnes
Re: Canon Vixia HF G30 camcorder - compression - color sampling 4:2:0 - Is a clean Chroma key possible?
on Dec 12, 2015 at 6:56:24 am

Thanks for your input Dave.

The Vixia HF G30 records at both 23.976 and 29.97. I prefer to shoot at 23.976. Also, I'm not sure if the camera can shoot 720. Just 1080 (but not 100% sure).

I'm actually not savvy enough when it comes to understanding 3:2 pulldown, so I'll have to learn about that.

When I bought this camcorder, I knew it wasn't a "professional" camera. But I gotta admit that I'm a little thrown off by this 4:2:0 business. Actually, I just learned that the 5D Mk ii and iii also are 4:2:0.

I see a lot of YouTube videos that were shot in front of a green screen and they look decent enough (to my eyes anyway). My goal for this project doesn't go much further than YouTube... so I hope I can find a workaround for this flickering edge problem.

Thanks again Dave - and if anyone else would care to give their 2 cents on what my options are, I would appreciate it. Thanks.


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Paul Neumann
Re: Canon Vixia HF G30 camcorder - compression - color sampling 4:2:0 - Is a clean Chroma key possible?
on Dec 13, 2015 at 1:09:45 am

I've gotten super clean keys out of a XA10 and think that uses pretty much the same image processor as the Vixia 30. So yes it's possible. Sounds like you've got enough light though probably pushing a lot of green into everything with all those fluorescents. One thing to check is having Keylight set to Intermediate Result and not Final. That'll drive anybody nuts.


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Michael Arnes
Re: Canon Vixia HF G30 camcorder - compression - color sampling 4:2:0 - Is a clean Chroma key possible?
on Dec 13, 2015 at 1:32:30 am
Last Edited By Michael Arnes on Dec 13, 2015 at 1:33:18 am

Thanks for your input Paul. It's reassuring to hear that I can still get good results with this camera.

Regarding setting Keylight to "Intermediate Result", do you mean that I should keep it on there even when rendering the file? Or just when adjusting my key and matte settings?

I seem to recall that I tried the "intermediate result" before, and I ended up with a very altered color on my background (instead of transparency). Maybe I'm doing something wrong...

Also, do you tend to do any pre-processing on your footage before applying Keylight? (eg. Denoiser) Is there anything that can help reduce the DV artifacts before keying out?

Thanks again!


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Ralf Eilers
Re: Canon Vixia HF G30 camcorder - compression - color sampling 4:2:0 - Is a clean Chroma key possible?
on Jan 4, 2016 at 11:43:52 am

Hi Michael, hello from Germany.

At first let explain, that I'm not a Pro, but a guy who's ready and willing to test every way to find the best result on doing a nice Chromakey! Well I've checked many forum to find out, what is the best Camera, what about good lightning methods and what is the best Green Screen Backround Solution! Many ways leads to Rom but it is not too difficult, to get good results as long as you're testing on some settings. My first Camera was a Black Magic Pocket, which is a very good thing to fit the ProRes 4.2.2. But this Camera is also a Weapon and you must be a bit more a Professional to understand everything about it. I failed to handle this Camera and so I decided to give the Canon HF G30 a Go. I was pretty much impressed by the first results and it takes not long to find out, that my lightning method is the main prob. So I've bought me a good 5 Point Starterkit (take care of too much light. Sometimes less is more) for almost 130bugs and the results gets better and better. I've also bought me the right Chromakey Color from Ebay for 73bugs to paint my Walls. This was another good decision I made. The final touch to have almost perfect results was to buy me the Software Compressor and Final Cut Pro X from Apple. Not the best Programs in the top ranking, but with the Compressor you can do the ProRes422HQ and the Keyer inside FCPX works like a charm and delivers good results within minutes. By the way you can get a lot of free Plugins for FCPX, or many for less money from Motionvfx, or Pixel Film Studios. This will help you to produce very professional Videos. Well! Hope this will help a bit and sorry for my pore english.

Cheers Ralf

BTW: My Camera Setting is only in manual Mode at 50.00P/28Mbps.


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