Hi, I'm on Windows and uses Xvid which can be rendered by use of Directshow - if you have the codec installed. I use Xvid because the decoding doesn't stress my CPU to much and the file size is not to big.
For the transcoding part, I use FFmpeg. FFmpeg can transcode from just about any format - now even ProRes, and make a Xvid video output. I use FFmpeg with the following parameters:
ffmpeg -i input.mov -g 2 -s 768x432 -an -qscale 3 output.avi
-g 2 means that the GOP size is 2 - that makes every 2nd frame a keyframe, so skipping is easy for Reaper. -qscale denotes the quality - less makes bigger files. I only use 768x432 pixels which is big enough for my purpose.
Get FFmpeg for Windows here:
http://ffmpeg.zeranoe.com/builds/
Get Xvid codec here:
http://www.xvid.org/Downloads.15.0.html
Regards,
Frederik