Sequence Display Extension in GSpot

[sambat]

What does the Sequence Display Extension number signify in a DVD?

[aedipuss]

hover your mouse pointer over anything you want info on.

[sambat]

You don't know either, eh?

[aedipuss]

a guess - it doesn't apply to mpeg-2 - it's just random numbers in the file.

[Alex_ander]

Sequence display extension is defined in H.262 (mpeg2) format as an optional mpeg2 data. It defines the part of display in pixels (different from encoded resolution) corresponding to the standard DAR of 4:3 or 16:9. This allows for calculating/displaying e.g. in ITU proportions, while by default (sequence display extension not present) the proportions are set directly from 'DAR + resolution'. This is explicitely pointed in H.262.
Sometimes you can see similar GSpot picture for a file with fake (patched for DVD authoring) resolution numbers (e.g. 544x576 -> 720x576). So for a file of unknown origin I'd additionally check its actual resolution in DGIndex.

P.S.
Not sure but 540 hor. number might also come from Pan & Scan setting of the authored DVD.

[sambat]

The 540x576 seq entry is on the R2 disk of 'The Thick of It' Special (Rise of the Nutters)

check its actual resolution in DGIndex.

DGIndex shows it as 720x576.

I have seen an entry for seq in some other BBC disks, but when it's there it's the same as the 'pic' number.
Pan & Scan sounds like the answer.
Much obliged.