i.e. the four bytes 00 00 01 0a.
When decode_nal() decodes the end of sequence NAL unit, it returns with
dst_length == 0. The original code leads to a return -1 which discards
the current properly decoded frame.
patch by Reinhard Nissl, rnissl gmx de


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@8688 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b