Just to reiterate Daremos' posts above, please see via the link below, a post I wrote at another forum showing which settings seem to work with both 224x174 and 320x240 res Rockchip players. I am not sure about those which require rotation though, as I don't have such a player...
http://www.mp4nation.net/forum/viewtopic.php?t=296
When I get time, I will post this properly on this forum ( I though I already had, but couldn't find it!!)
Please note, ViDrop is rapidly becoming a fantastic 'freeware' partner for your Rockchip (please can someone post a ViDrop link?).