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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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