FFmpeg/Swscale

http://stackoverflow.com/questions/3367187/what-is-lib-swscale-used-for-by-ffmpeg-programers

- Swscale is mainly used for players, not encoding/decoding
- at a different pixel size/aspect ratio,  colorspace conversion between various RGB and YUV color formats
- no faster software implementation presently exists for any of them, at least on x86 and x86_64