Source code is available if you need better speed control but it's open for you to tinker inside.
There are open source programmers that will tailor it to your needs.
I'm looking for a media player that can play many codecs and manually adjust the play rate between 100%-200% (with sound).
I know Windows media player 10 can do this but only for most audio files and some video files.
Preferably free, but if you know a good one that has to be bought, I am willing to pay.