Poll: The ammount of overscan for SNES games on your TV

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How much does your TV display?

Entire screen is showing
5
56%
Less or equal to 16 pixels clipped evenly between top and bottom
3
33%
Less or equal to 16 pixels clipped unevenly between top and bottom
1
11%
More than 16 pixels clipped evenly between top and bottom
0
No votes
More than 16 pixels clipped unevenly between top and bottom
0
No votes
 
Total votes: 9

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Drew Sebastino
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Poll: The ammount of overscan for SNES games on your TV

Post by Drew Sebastino » Thu Dec 15, 2016 10:25 pm

In working with the SNES, I've found the 6KB per frame upload limit to be very restrictive. I've been very reluctant to use forced blanking, but I thought to myself about how most TVs probably don't even display the entire screen. Mine doesn't; it leaves off the top 8 pixels and the bottom 8 pixels almost exactly (it fluctuates based on how bright the screen is).
Last edited by Drew Sebastino on Fri Dec 16, 2016 5:42 am, edited 2 times in total.

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Re: Poll: The ammount of overscan for SNES games on your TV

Post by tepples » Thu Dec 15, 2016 10:38 pm

Too bad you made this an "only one option" poll, or I'd be able to go through all TVs in my house and NovaSquirrel's and run the overscan test in 240p Test Suite (PVSnesLib edition) on all of them. So I went based on the HDTV in front of me, which shows all 256x224 pixels when zoomed out. (When zoomed in, it's closer to 256x168.) One Apex TV that I have packed away has a huge overscan; I've been meaning to figure out how to get into its service menu.

The official title safe area (for text and status bars) is 224x192, or a margin of 16 pixels from each side.

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Re: Poll: The ammount of overscan for SNES games on your TV

Post by dougeff » Fri Dec 16, 2016 5:38 am

Agreed, I have 3 TVs and they all show differently. I'll try to measure it sometime.
nesdoug.com -- blog/tutorial on programming for the NES

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Drew Sebastino
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Re: Poll: The ammount of overscan for SNES games on your TV

Post by Drew Sebastino » Fri Dec 16, 2016 6:03 am

I just edited it to include more poll opti ons. The way I know my TV blocks out that much is that R-Type III cuts off the top and bottom 8 pixels, and where its showing is perfectly after the black from comparing it an emulator. I think 90% of games would not fit under the safe zone, (I even have trouble with some games) that seems very harsh. I never payed attention to how much if the screen is not showing on the sides, but I just had the idea you could cut 4 pixels off the sides of the screen with one window layer (?) and only need a 32x32 tilemap. I had been looking at the possibility of using a 16 pixel tile tilemap as I'm trying to port a Neo Geo game, but I found you actually still save on memory because you can better cut out a BG if it has large transparent areas. Also, I like how if I were to update tiles, I could do them in a straight shot.

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Re: Poll: The ammount of overscan for SNES games on your TV

Post by TmEE » Fri Dec 16, 2016 8:29 am

I see all the active video, horizontally and vertically (but only because I've confed all my TVs to do that).

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Re: Poll: The ammount of overscan for SNES games on your TV

Post by psycopathicteen » Fri Dec 16, 2016 10:36 am

Espozo wrote:In working with the SNES, I've found the 6KB per frame upload limit to be very restrictive. I've been very reluctant to use forced blanking, but I thought to myself about how most TVs probably don't even display the entire screen. Mine doesn't; it leaves off the top 8 pixels and the bottom 8 pixels almost exactly (it fluctuates based on how bright the screen is).
...and with OAM you only have a little more than 5KB left, and only 4KB if you're doing a lot of individual 16x16 sprites.

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Re: Poll: The ammount of overscan for SNES games on your TV

Post by Bregalad » Fri Dec 16, 2016 12:06 pm

How much does your TV display?
And how are we supposed to know ? Isn't there a test ROM or a common game that can be used to test this ?
Since I have a PAL SNES and PAL TVs I suspect that overscan is always showing anyways but this is not an interesting case so I do not answer the poll.

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Re: Poll: The ammount of overscan for SNES games on your TV

Post by psycopathicteen » Fri Dec 16, 2016 12:10 pm

You can count the number of wood panels around the title screen of Super Mario World.

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Re: Poll: The ammount of overscan for SNES games on your TV

Post by tepples » Fri Dec 16, 2016 12:16 pm

Bregalad wrote:
How much does your TV display?
And how are we supposed to know ? Isn't there a test ROM or a common game that can be used to test this ?
tepples wrote:run the overscan test in 240p Test Suite (PVSnesLib edition)
That's this.

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Re: Poll: The ammount of overscan for SNES games on your TV

Post by lidnariq » Fri Dec 16, 2016 12:38 pm

Espozo wrote:SNES [...] 6KB per frame [...] forced blanking [...] leaves off the top 8 pixels and the bottom 8 pixels almost exactly
So. SNES. Therefore 170.5 bytes of DMA per scanline.
6KB per frame means ≈35 scanlines of blanking. Meaning you're already talking about NTSC SNES in the 224 line mode.

I haven't seen an NTSC CRT TV manufactured since the late '80s that displayed meaningfully fewer than 224 lines of picture.

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Re: Poll: The ammount of overscan for SNES games on your TV

Post by Myask » Fri Dec 16, 2016 12:48 pm

Does the SNES not bother outputting 240 whole lines? Huh.

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Drew Sebastino
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Re: Poll: The ammount of overscan for SNES games on your TV

Post by Drew Sebastino » Fri Dec 16, 2016 12:51 pm

The SNES can either output 240 lines (which nearly no game does) or 224 lines (99% of games). Many games, already using 224 lines, will use forced blanking to be able to upload more data. I want to use 224 lines, and then force blank out the top 8 and the bottom 8 for 208 lines total.

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Re: Poll: The ammount of overscan for SNES games on your TV

Post by lidnariq » Fri Dec 16, 2016 12:58 pm

The SNES emits either 224 or 239 (yes, really) scanlines.

I'm really skeptical of Espozo's assertion that "many" or, for that matter, more than a tiny handful used forced blanking to reduce the vertical height from 224 scanlines.

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Bregalad
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Re: Poll: The ammount of overscan for SNES games on your TV

Post by Bregalad » Fri Dec 16, 2016 1:14 pm

lidnariq wrote: I'm really skeptical of Espozo's assertion that "many" or, for that matter, more than a tiny handful used forced blanking to reduce the vertical height from 224 scanlines.
Agreed. Also it'd be interesting to know which of those (so called) 1% of games uses the 240 lines mode.

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Re: Poll: The ammount of overscan for SNES games on your TV

Post by psycopathicteen » Fri Dec 16, 2016 1:45 pm

It's actually 165.5 cycles per line because of the stupid 5 cycle DRAM refresh cycle.

I think the 240 line mode is only available on PAL systems. I've tried using 240 mode before, nothing happened.

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