av_find_stream_info() end check fixes   10l (wrong time base)   use timestamps if duration isnt available
av_find_stream_info() end check fixes
  10l (wrong time base)
  use timestamps if duration isnt available


git-svn-id: a4d7c1866f8397a4106e0b57fc4fbf792bbdaaaf@4301 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

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