Check dimensions to avoid division by zero due to invalid new dimensions. Partially fixes http://bugzilla.mplayerhq.hu/show_bug.cgi?id=773.
Check dimensions to avoid division by zero due to invalid new dimensions.
Partially fixes http://bugzilla.mplayerhq.hu/show_bug.cgi?id=773.


git-svn-id: a4d7c1866f8397a4106e0b57fc4fbf792bbdaaaf@8321 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg