5 replies to this topic

[Wrathchild]

Hi,

In playing AR: The Dungeon's intro under emulation, my ears
don't like the tune played at 50Hz and find it much better at 60Hz.

Whether or not patching it to auto-detect the machine's rate and
playback accordingly would actually fix this is possible, it got me
thinking that a list could be compiled of those titles that people
know have issues and maybe during 2006 the programmers
amongst us can hack some of them to work correctly.

I guess games with timers, e.g. counting down, could suffer
this problem and playing it in one country either puts one
user at an advantage, e.g. more time than was originally
intended, or at a dis-advantage, e.g. the game runs out
sooner than it normally would.

I would be good to also confirm the games that check this
correctly and adapt accordingly.

Regards,
Mark

[Goochman]

As we found out in the High Score Club Pole Position has this problem. Its hard to break 106K in NTSC mode but 114K+ is quite easily achieved under PAL mode.

I would presume anything timer bonus related will have an issue.

[emkay]

Sea Dragon
That game gets boring slow when playing it at 50Hz.

Popeye
It makes more fun at 60Hz

Salmon Run
At 50Hz you cannot escape the Bears, when it is possible at 60Hz.

[Rybags]

Most games use timers based on the VBI. Although you can get near identical timing using POKEY, I feel it to be a bit of a waste of time, plus you lose the use of 1 sound voice.

Of course, well written software could use fractional increments for sprite movement, and other techniques to keep music the same speed, but in my experience, I haven't really come across any such software.

Machines like the ST and C-64 had the advantage of 100Hz timer interrupts which were built in to the OS/HW, but games tend to ignore them since they're not based on the VBlank interval.

[Plastron]

In my games i used $14 as the way of moving items without screen flicker so i guess they will all run faster on a 60Hz machine.

loop lda $14
cmp $14
beq loop

If you do this before any screen action results will be flicker free. But timing is different 50 to 60 Hz

Andy

[Rybags]

One of the big problems with the older computers is that moveable objects are usually 2D sprites with a fairly defined pattern, as compared to more modern games with anti-aliased 3D textured objects.

Once you start moving objects at fractional rates (which you would have to do to get the same speed with PAL/NTSC) you can really see some jerkiness coming in.

I found that I could get the best sprite movement using the following method for velocity control. Imagine the sprite as having a byte as follows for velocity:

76543210
DIIIFFFF

D is a direction flag (1=left, 0=right)
III is the increment component. The number of pixels per frame to move the object to the left or right (as flagged by D).
FFFF is a fractional component. It gets added to a 4-bit counter. If the counter overflows, then for that frame only, add 1 to the increment component.

With variations of that technique you can have multiple objects with unique speeds, and not have to use too much processing overhead.

Edited by Rybags, Fri Dec 23, 2005 7:26 AM.