some sanity checks on what is muxed, invalid timestamps in mpeg are very common and lead to strange errors in the mpeg muxer otherwise
some sanity checks on what is muxed, invalid timestamps in mpeg are very common and lead to strange errors in the mpeg muxer otherwise


git-svn-id: a4d7c1866f8397a4106e0b57fc4fbf792bbdaaaf@3752 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

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