Maximum Scanline for NTSC? (and related questions)

[vdub_bobby]

I used to know this, but it has been too long and I can't remember.  And I'm sure it's in the forum somewhere, but I can't find it.  So:

 

What is the maximum scanline count for an NTSC game and still have a stable display? I know 262 is standard.  I guess knowing the minimum would be nice too

 

And similarly, max / min for PAL and SECAM?

 

Thanks in advance... ?

[Thomas Jentzsch]

That solely depends on the TV. Some have a larger sync range than others.

[tokumaru]

I wouldn't deviate much from the standard, specially now that we rely heavily on digital devices to process these video signals, and most of these decoders aren't as tolerant as analog TVs were back in the day.

[tabar]

192.

 

Stella programming guide

[vdub_bobby]

On 2/20/2022 at 8:00 AM, tokumaru said:

I wouldn't deviate much from the standard, specially now that we rely heavily on digital devices to process these video signals, and most of these decoders aren't as tolerant as analog TVs were back in the day.

Thanks.  Does that mean issues have come up with my games that don't run exactly on the standard?

 

Elevators Amiss I think runs at 270.  Can't remember the others.

 

[tokumaru]

4 hours ago, vdub_bobby said:

Thanks.  Does that mean issues have come up with my games that don't run exactly on the standard?

I haven't had any issues myself, because I mostly use old CRTs for my retro gaming needs, but I've heard of cases where capture devices and modern TVs/monitors would have a hard time locking to non-standard video signals, sometimes refusing to display anything. I can't recall of any sources for this though, so take it with a grain of salt. Sorry if I can't be of much help, hopefully someone more knowledgeable on video signals can give you a better answer.

[Thomas Jentzsch]

Generally it is better to aim for 60Hz, since modern hardware expects that. Some TVs may have problems with anything else, especially when trying to "optimize" the picture. If you are full retro and do not care for modern TVs, anything around 262 +/- 15 lines should work just fine on most CRTs.

[vdub_bobby]

1 hour ago, Thomas Jentzsch said:

Generally it is better to aim for 60Hz, since modern hardware expects that. Some TVs may have problems with anything else, especially when trying to "optimize" the picture. If you are full retro and do not care for modern TVs, anything around 262 +/- 15 lines should work just fine on most CRTs.

PAL also?  60 Hz for PAL?  Or does 50Hz for PAL still work?  I think for Squish 'Em and Elevators Amiss the PAL roms are 60Hz but I'm pretty sure Go Fish! is 50Hz.

[JetSetIlly]

8 minutes ago, vdub_bobby said:

PAL also?  60 Hz for PAL?  Or does 50Hz for PAL still work?  I think for Squish 'Em and Elevators Amiss the PAL roms are 60Hz but I'm pretty sure Go Fish! is 50Hz.

 

50Hz for PAL, which is 312 scanlines.

 

PAL60 is 60Hz, or 262 scanlines.

[glurk]

If you load up a bunch of games in Stella (I did...) and check the scanline count in the debugger, you'll generally see that most "name brand" Atari, Activision, etc...  stick right to 262.  Other third parties games have more variance.

 

I'm no expert on it, but I'd say the more that you vary from that 262 'standard' the greater the likelihood of creating a problem for someone, somewhere, who has a less tolerant display device.  But many old games do vary from that, and I've never heard too many complaints.  I think it's more a "rule of thumb" and an "advised baseline."

 

[JetSetIlly]

Combat (!) has 263 lines, so there is that. The Activision Ventian Blinds demo meanwhile, has 267. The "curtains" loading screen for Supercharger cassettes doesn't sync at all!

 

So yes, even back in the day, 262 wasn't a fixed rule.

 

But if people report that those ROMs have issues on modern TVs then I suppose we should be more careful with modern ROMs.

 

The most important thing IMO is consistency. If you're going to output 263 lines then it should be 263 every frame

Edited February 22, 2022 by JetSetIlly