private FilgraphManager ifilmanager = null;
private IMediaPosition iposition = null;
ifilmanager = new FilgraphManager();
iposition = (IMediaPosition)ifilmanager;
Normal speed is iposition.Rate = 1.0;
Half Speed is iposition.Rate = 0.5;
Twice Speed is iposition.Rate = 2.0;
Negative rates indicate reverse playback; however, most sources do not support reverse playback.