#Flicker drives me nuts
06-Apr-94 23:57:41
Sb: #138193-#Flicker drives me nuts
Fm: Ronald B. Romine 70322,1525
To: Carl Hansen 75300,1050
CH >>My problem is that in the higher resolutions there is some pretty bad
flicker.<<
What monitor drivers are you using? You can have high resolutions with
both the NTSC & PAL drivers, BUT you need to use the Double-NTSC &
Double-PAL drivers to have a higher refresh rate.
The Double-NTSC, Double-PAL, Euro72, & Multiscan drivers, have a vertical
refresh rates almost twice that of the NTSC, PAL, & Euro36 drivers.
The Super72 driver, can generate a 800×300 screenmode with a vertical
refresh rate of ~24-kHz (higher that NTSC, but lower than Multiscan),
and a horizonal refresh rate of 72-Hz. The screen can be interlaced for a
resolution of 800×600.
—
If the screen isn't properly centered, try using the Overscan program,
located in the PREFS drawer. It will need to be used for each monitor
driver. If that doesn't help, look on local BBS's for either
"setp4014.lha" or "1942mon.lha", or "V39_update.lha", which contain
updated versions of the monitor drivers, Overscan, and the Setpatch.
—
Selecting the "mode promotion" option of Icontrol, will inform the system
that you want the Dbl-PAl & Dbl-NTSC drivers substituted for the PAL &
NTSC screens.
Icontrol doesn't work too well. Look in the Libraries for a program
called "PPrefs.LHA". This is a promoter that works with most screens &
resolutions, and it allows the user to select what screen types get
promoted and what mode to promote them into.
—
CH >>Is this related to the software deinterlacing done on the A1200 as
opposed to the hardware deinterlacing done on my A3000s?<<
Yes, and no.
In the past the hardware de-lacers for the Amiga, would convert ~15-kHz
NTSC & PAL screens into ~31-kHz VGA screens. They captured the video data
after the screen was generated, re-mixed it, and sent the video signal out
at a higher rate. The Amiga's output hadn't changed, it was simply
intercepted, and altered.
The de-lacers expected to find only ~15-kHz video signals, and resolutions
of 320 or 640 pixels wide, and 200 to 512 pixels tall.
The AGA (& ECS) now outputs ~15-kHz, ~24-kHZ, ~31-Khz, with resolutions
from 160 to 1280 wide, and 150 to 1024 pixels tall. De-lacing became a
little more complicated.
The A1200's (& A4000's) mode promotion feature attempts to identify what
screenmode is being used, see if there is a alternative listed, then
create that screenmode instead. There isn't any real de-lacing since the
promotion allows skipping the generation of the laced version of the
screen.
Promotion, would be better described as a screenmode/resolution cross
matching system for selecting one of many alternative screenmodes.
—
There are a few problems with the promotion.
First, the system has to signaled, that you want a screenmode promoted.
Programs that use a custom bootdisk, often will not include a way to
activate the promotion.
Second, the built-in promoter only bothers to promote a limited number of
resolutions. This can be fixed by a third party promotion software, such
as PPrefs.
Third, there are programs whose graphics bypass the OS, preventing the
promoter from substituting the requested screenmode for that program.
These programs may be system friendly in every other way, but the OS's
graphic system is blind to their existance.
Ron.
– ap'ing with AP. (Eagles may fly, but weasels aren't sucked
into jet engines.)