Fortress.alm from Rance IX uses an MPEG-2 Program Stream containing
MPEG-1 video and MPEG-1 Layer II audio. As far as I checked, it is the
only .alm movie released in Japan that does not use an MPEG-1 Program
Stream.
The existing pl_mpeg decoders support its elementary streams, but the
demuxer rejects its MPEG-2 pack and PES headers. Extend the demuxer to
parse those headers and the PTS/DTS combinations used by Fortress.alm.