Date   : Sun, 28 Sep 2008 13:25:05 +0100
From   : bbcmailinglist@... (Ian Wolstenholme)
Subject: Domesday video problems

Just a couple of things to check, although I'm not sure they will make
any difference:

Make sure the Replay button at the back of the LV-ROM player is switched
off.
Also try adjusting the horizontal shift by twiddling the H-SHIFT control
at the back
next to the SCART socket.
If you are using a SCART connector between the LV-ROM and monitor,
check that all the pins are connected straight through and the lead is in
good working order.
You might also trying playing a laserdisc on a normal TV with SCART just to
make sure it's not the LV-ROM which doesn't like the monitor.
With the volume turned up on the monitor, do you get the Domesday
music (or any sound from another laserdisc) when the disc starts playing?

Looks like a good setup, hope you can get it working!

Best wishes,



Ian

----- Original Message -----
From: Adam Sampson [mailto:ats@...]
To: bbc-micro@...
Sent: Sun, 28 Sep 2008 13:16:39 +0100
Subject: Re: [BBC-Micro] 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/>

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