Date   : Sun, 28 Sep 2008 13:16:39 +0100
From   : ats@... (Adam Sampson)
Subject: Domesday video problems

"Mark Haysman" <jumbos.bazzar@...> writes:

> I'm not familiar with that particular player, but it's not been set to
> NTSC has it? (If it has an NTSC option?)

I'd wondered that, but no, it's a PAL-only player. The fact that there
are patches of correct colour suggests that the colour decoder is
basically working, since Laserdiscs carry (FM-encoded) composite video,
and the monitor's connected to the decoded RGB output from the player.
I need to have a look at the undecoded composite output, though...

> I presume the Beeb loads a program from the LV rom that corresponds to
> the images on the disc?

Yup. Looking at the service manual I've just been sent (thanks again!),
the data track is stored similarly to how digital audio is on later
Laserdiscs -- i.e. like Red Book CD audio. The player uses a chipset
designed for CD players that uses a PLL to recover a bit clock from the
data stream, so it can handle small variations in disc speed, but it
should complain if it drifts too far away.

I'd be interested to see what happens if you play a Domesday laserdisc
on a modern Laserdisc player with digital audio support -- is the data
format close enough that you can read the VFS data from the player's
digital audio output?

Thanks,

-- 
Adam Sampson <ats@...      >                         <http://offog.org/>