Re: V-Box

From: Nicolas Welte (
Date: 2000-08-24 14:26:53

Mark wrote:
> Regarding the not-supported PAL thing. In reading specs for several things
> like this (and PC TV tuner cards), they often state that a wide range of
> video standards are supported. However, this usually refers to the range of
> models which are available. Any given unit may only support one standard.

I had a BT848A based TV card myself, and it was compatible with PAL and
NTSC equipment. It was already one of that low cost cards with only one
single clock crystal, but starting with the 848A chip they have an internal
PLL that can produce all needed frequencies from a single crystal. Older
cards with the BT848 needed two crystals, so low cost cards with only one
crystal were either PAL-only or NTSC-only. On newer cards it is simply a
matter of software.

My card had a bad bug in an early software version that did not allow
proper handling of the SVideo input, all colors were wrong. Composite
worked fine, though. If none of them works in color, it might be worth a
try to readjust the color carrier frequency of the computer: there is an
adjustable pot or cap near the VIC-II chip, often readjusting that helps
with some equipment. For example, my 1702 and 1084 monitor display color
pictures for all of my PAL-Commodores, but my Sony TV set is very picky
about the correct frequency and I have to readjust some of my machines to
work with that TV. I can imagine it is the same with TV cards or
scandoubler devices, since all of them work with digital video processors.

I think I already reported this, but I also have a scandoubler device, a
noname (at least nobody would recognize it) TV tuner box for VGA monitors.
It has inputs for antenna, composite video, s-video, VGA, sound, and
outputs for VGA, sound and composite video. It does not convert VGA to
composite of course. I am quite satisfied with that device, colors are very
stable, but naturally the pixels in horizontal position have interpolated
color values, because the pixel clock of the device does not match the
pixel clock of the C64. But that doesn't matter, I don't see it anymore.
Vertically the scanlines are doubled, and this gives the display that well
known look of low-resolution VGA modes as they were popular for so many
years in PC games. It also displays both PAL and NTSC signals if they're
applied to the composite or s-video input, but it does not like nonstandard
video timings with more than 60Hz refresh rate. But I expected that :-)

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