Since there is no information about the source format, "unspecified"
is the correct value to write here.
All tests using the MPEG-2 encoder are updated, as this changes the
header on all outputs.
Improves compatibility with XDCAM HD formats. It has been set for a long time
in ffmbc.
Reviewed-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Marton Balint <cus@passwd.hu>