Thank you for your kind sentiment regarding RealVideo 10 quality. Unfortunately, it appears you have (re-)discovered a bug. The 60 fps bug was fixed back in 2003, but I am sad to say, something broke it again. It is not quite as bad as before though. It turns out you can encode 59.999 fps, just not 60 fps. There must be a mistaken '<' instead of '<=' somewhere :(. Here is the original bug report: you have to login to hc.org to view it. I will either re-open this, or file a new bug. To get around the bug, you can use AviSynth :P AVISource("my60fpsfile.avi").AssumeFPS(59.999) or any other way to change the fps to less than 60.. Frankly, 60 fps color video sequences should not really exist... A 29.97 fps file, at double the framerate, should be 59.94 fps, AFAIK. Thanks! P.S. I don't understand the stats in ZoomPlayer either. When I encode 59.97 fps, it reports the wrong framerates. RealPlayer reports the right framerates. See attachement.