DSS sample rate lookup use hex keys
MPEG-video module rewrite (partial)

Rewrite MPEG-video parsing to be more systematic, walking through each
data block and extracting data as needed. Added accurate-but-slow method
of walking through each GOP for VBR files to get accurate playtime.
Already noted that some VBR files (with a targeted average bitrate) do
specify an actual bitrate rather than 0x3FF that normally indicates VBR,
for these playtime may be sightly off.
AC3 and DTS audio not yet supported at all.
MPEG audio supported by previous hack, still don't understand Packed
Elementary Stream header (my interpretation of documentation doesn't
match any sample files)