How much flicker can you take?

[MausBoy]

In the game I'm working on, it's hard to not have at least a few enemies and powerups on the screen at any given time, but having more than one causes flicker. Which is better, a less busy game without flicker, average action with light flicker, or lots of action with lots of flicker? Can you point out examples where the flickering was ok, and ones where it was awful?

I don't know what the "hz" references are that I've read here, if someone could post a link or an explanation that'd help a lot. Personally I don't think it looks too bad as long as it's 3 or less sprites, but I don't want to go to a lot of trouble on the kernel and then have people hate it because of the flashing sprites.

[Rybags]

Depends on the system being developed on.

 

For a 2600, it's par for the course for many games.

 

For the computers, it's something best avoided but inevitible in some cases.

 

60Hz/50Hz is the refresh rate for most older computers/consoles which attach to TVs. 60 being NTSC (mainly USA, Japan) and 50 for PAL (just about everywhere else). Displaying a sprite every 2nd frame effectively makes it 30Hz or 25 Hz.

 

By "sharing" a sprite, you only display it every nth frame. Sharing it more than once, you get a situation where it might only appear once every 4-5 frames.

 

Having a sprite visible 50% of the time is acceptable, but noticable. Anything less is definately noticable. When it gets down to <33% it becomes downright annoying.

[+batari]

In the game I'm working on, it's hard to not have at least a few enemies and powerups on the screen at any given time, but having more than one causes flicker. Which is better, a less busy game without flicker, average action with light flicker, or lots of action with lots of flicker? Can you point out examples where the flickering was ok, and ones where it was awful?

I don't know what the "hz" references are that I've read here, if someone could post a link or an explanation that'd help a lot. Personally I don't think it looks too bad as long as it's 3 or less sprites, but I don't want to go to a lot of trouble on the kernel and then have people hate it because of the flashing sprites.

"Hz" means the number of frames per second the sprite is actually displayed on the screen. I.e., 30 Hz is every other frame, since a NTSC television displays 60 frames per second.

 

Purists like no flicker at all, but the rest of us don't mind minimal flicker if used appropriately. Most regard 30 Hz as acceptable in most cases since it's not terribly noticeable. A television's phosphor persistence reduces apparent flicker, and newer emulators have a setting to reduce flicker as well, such that 30 Hz looks fine to most.

 

Going less than that, i.e. 20 Hz or every 3rd frame, is OK for certain situations. The explosions in Missile Command are at 20 Hz, but this isn't a big deal since they are explosions, and it helps that they don't move.

 

The ghosts in Pac-Man are 15 Hz or every 4th frame, and most seem to consider them too flickery, though the game is still playable.

[cd-w]

I think that my Juno First game will soon take the prize for the most flicker in any 2600 game However, I generally think it is a good idea to try to reduce or avoid flicker as much as possible. Nonetheless, a little flicker is basically unavoidable on the 2600 is you want more that two sprites in the same horizontal region. As noted elsewhere, 30Hz flicker will not be particularly noticable on a real TV set, particularly if coloured backgrounds are avoided.

 

Chris

[MausBoy]

The games I'm making are for the 2600, they always have colored backgrounds, and since i'm using bB the flicker happens if I want more than two sprites period.

 

Thanks everyone for the helpful advice. With my first homebrew, I'm going to try not flickering the player sprite, and never having more than two other sprites at once. So I'll have no more than one non-flickered single color sprite, and two 30hz flickered multicolor sprites on screen at once.

 

I think it looks kind of strange, especially compared to the nice solid player sprite. I also don't know how to sync stella to my monitor, so I don't know if I'm seeing the flicker correctly during development.

 

I'll attach an example where both sides of the 32 pixel wide sprite are supposed to have 30hz flicker, but it isn't working out that way. I notice a big different in the two sides, can anyone tell why they are out of sync and what hz the right side is going at?

00vpsmg1.bin

[jpfalcon2003]

I'd say average with light flicker. As long as the gameplay is fun, it's easily dismissed. I seen a copy of Defender. The ship actually becomes invisible. That one is ridiculous. Compare it to Defender II.

[Thomas Jentzsch]

IMO constant flicker is less noticable than flicker going on an off. 30Hz should still be the limit.

 

But when flicker is switched on and off, sometimes it helps making the objects brighter while flickering.

[Thomas Jentzsch]

I'll attach an example where both sides of the 32 pixel wide sprite are supposed to have 30hz flicker, but it isn't working out that way. I notice a big different in the two sides, can anyone tell why they are out of sync and what hz the right side is going at?

Left is on 2 out of 3 frames, right 1 out of 3.

[+stephena]

I think it looks kind of strange, especially compared to the nice solid player sprite. I also don't know how to sync stella to my monitor, so I don't know if I'm seeing the flicker correctly during development.

If you use OpenGL mode and turn on 'sync to vblank' in your OS video setup, then Stella will be synced to whatever refresh rate you're currently running at. Combine this with an LCD display that always runs at 60Hz, and Stella updates will be silky smooth, and correctly synced. Of course, you don't have to use an LCD to get the 60Hz refresh rate, but it certainly looks better than a CRT @ 60Hz.

[MausBoy]

When I set it to OpenGL, I just get a white screen, and then I can't even open the menu to change it back without opening the settings file.

[Christophero Sly]

For most games, like Asteroids and Defender, flicker doesn't bother me. However, some games, like Superman, suffer extreme flicker when multiple characters are on screen. Long-term exposure to that kind of flicker can't be healthy. I played game after game of Superman in succession for several hours trying to beat my best time and after that session I could see those gangsters on the insides of my eyelids. Exposure to that kind of flicker even made it difficult to sleep. Unfortunately, the flicker is so bad in Superman, that I've pretty much given up on any attempt to break 50 secs.