stream alignment" descriptor decoder and generator (not tested).
  * src/descriptors/dr_07.h, src/descriptors/dr_07.c: MPEG2 "target
    background grid" descriptor decoder and generator (not tested).
  * src/descriptors/dr_08.h, src/descriptors/dr_08.c: MPEG2 "video
    window" descriptor decoder and generator (not tested).