Multiplexing and modern (flat-panel) TVs

[Carl Mueller Jr]

Hello all,

 

I'm not really an Atari 2600 programmer, although I am somewhat familiar with the hardware. Based on the severe sprite limitation, I'm assuming that "multiplexing" is often employed as a solution. Just to be clear, I'm talking about sprite cycling – displaying two different objects, say, using the same sprite, by swapping them every other frame.

 

My game is actually written for the Intellivision, which does not commonly employ multiplexing (one reason being that it was forbidden by Mattel back in the early 80s, and not really considered necessary given that it can display a whopping 8 sprites without flicker). My game, of course does.

 

By displaying an object every other frame, I find that it gives a nice translucent effect on a CRT television – that is, a fairly stable looking image that you can see through. I designed my game with this type of multiplexing in mind.

 

Now, it seems, that some flat-panel TVs are having issues. Apparently, there are synchronization issues, causing some sprites to disappear altogether. I don't know if it's just dropping every other frame, or some frames are getting repeated and others dropped.

 

Does anyone know if there is a setting for such TVs to correct the problem? I imagine that many Atari 2600 titles would have similar issues and modern TVs.

 

I would appreciate any information.

 

Thanks,

Carl

[BladeJunker]

Hello all,

 

I'm not really an Atari 2600 programmer, although I am somewhat familiar with the hardware. Based on the severe sprite limitation, I'm assuming that "multiplexing" is often employed as a solution. Just to be clear, I'm talking about sprite cycling – displaying two different objects, say, using the same sprite, by swapping them every other frame.

 

My game is actually written for the Intellivision, which does not commonly employ multiplexing (one reason being that it was forbidden by Mattel back in the early 80s, and not really considered necessary given that it can display a whopping 8 sprites without flicker). My game, of course does.

 

By displaying an object every other frame, I find that it gives a nice translucent effect on a CRT television – that is, a fairly stable looking image that you can see through. I designed my game with this type of multiplexing in mind.

 

Now, it seems, that some flat-panel TVs are having issues. Apparently, there are synchronization issues, causing some sprites to disappear altogether. I don't know if it's just dropping every other frame, or some frames are getting repeated and others dropped.

 

Does anyone know if there is a setting for such TVs to correct the problem? I imagine that many Atari 2600 titles would have similar issues and modern TVs.

 

I would appreciate any information.

 

Thanks,

Carl

I'm not anywhere near an expert but what I do know is that only some flat screens have those type of options for CRT based issues and that without those settings you'll have to alter and optimize your code to correct it, maybe even have multiple kernels if your type of flickering varies enough from screen to screen. SeaGTGruff was telling that he was getting different results on his LCD screen based on plain flicker or interleaved flicker where plain flicker was working better on his modern set since it would interlace the varied passes into one visible image. Like I said I'm not the one to ask but I think I'm in the realm of what your asking.

[BladeJunker]

Actually that is a lot of multiplexing at 8 sprites when you consider that the average maximum is 6 total and nothing else can occupy its scanlines. Have you considered making variants of your sprites using Missile0, Missile1, and or the Ball object to lessening the amount of flicker put upon your Player objects?

Btw that is hilarious how Mattel forbade multiplexing on the Intellivision, I doubt the game industry could have functioned at all if the companies that made consoles stopped developers from trying new methods of rendering.

[iesposta]

I noticed flickering on my DLP projector sometimes causes sprites to display every other line and others get "interlaced" together.

Quite strange. I would not change my program just to make the projected image look better. It should work on a regular tube TV.

Also, some games that change screens cause the projector to lose synch and black out for a few seconds, ie Jr. Pac Man.

Sorry can't help with flat panel TVs.