Good Chroma Key?

After doing some Googling it seems there's not a very good chroma key solution for AS3. I found on Quasimondo a pretty nice one, but it's old and AS2 only and the video sample was only 320x240. I need a good clean key from a minimum of 960x540 (1280x720 ideally) webcam, and I'd really like it to run 24fps or so. Thought there might be an ANE for it, but I've found mostly poor examples using threshold and such. I think part of the problem is there's no other native color spaces in AS3 - if there were HLS or LAB space doing keying would be a lot less processor intensive - converting rgb to hls one pixel at a time is expensive.

Anyway thanks for any info.