Change the way the pixel-aspect-ratio is computed by
interpreting the sequence header aspect ratio info
as MPEG-1 values until a sequence extension or
sequence display extension is seen, and then updating
the sequence header struct accordingly.
Fixes incorrect anamorphic display on some MPEG-2 (DVD)
sequences.
... to allow for more efficient parsing and (more) consistent parsing API
among various codec parsers.
Fixes#672701.
Conflicts:
gst/videoparsers/gstmpegvideoparse.c