Xvid, DivX and MPEG4

I’ve just got a book on Video compression. The DVD format (mpeg2 compression) has been around for about a decade (mpeg2 I mean, not DVD per se). It’s also mpeg2 used for digital TV around the world. Yet you would have thought that in nearly 10 years the Next Generation would have come out…and been twice as good etc. Moores law.
Turns out it did and was called mpeg4 (name mpeg3 skipped for historical reasons), BUT they – the creators – put such restrictive licensing terms that The Industry rejected it. Only recently – after ‘hacked’ versions appeared – did they relent and change the conditions.
Too late, it would initially seem. The mpeg4 format really only appears as pirate Internet movie files in the XviD and DivX flavours. A tiny handful of “DVD” players support them. Pity; a 90 min (mpeg2) DVD movie could be 2 or 3 GB. XviD can squash this down to 700 MB and look pretty much the same.
But all may not be lost. At least one of the new “DVD” follow ons (Blu-Ray) will support mpeg4. A current single-sided, single layer DVD is 4.7 GB. The equivalent Blu-Ray – or BD – will be 25 GB. But we’ll need it. Even at that size a 25 GB disk recording of Hi Definition digital TV will only be about 2 hours! Already Sony are talking up dual layer 50GB BDs.