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Hey all,
Recently purchased a Game Gear version of Gunstar Heroes and while it seems to play OK, there is a LOT more flicker and sprite corruption than, say, in this video:

Most noticeable is on stage 1, there is a constant (annoying) bunch of light blue "dead spot" pixels that follow throughout on the left side of the screen. These reappear in later levels. Does anyone have a non-emulated version of this game they could check for me to see if my ROM is bad? I would most appreciate it. I tried on 2 Game Gears and the stuff is still there. I wonder if perhaps the GG emulation has something beefed up to help with this.

-Segasonicfan

Most emulators don't apply the sprite limits to get rid of flicker. See if you have an option to enable that (Meka has it) and compare again.

Thanks for the tip Maxim.

I tried the Meka with and without sprite limits now and it still runs AMAZINGLY better than my cart. I would still love it if someone who owns the game could verify what I'm talking about. Seems strange that it should run so different in emulation.

What you may be seeing (blue spots) is the palette colour 0 being changed every scanline to make the gradient on stage 1.

ccovell wrote

What you may be seeing (blue spots) is the palette colour 0 being changed every scanline to make the gradient on stage 1.

Thanks for the reply. I think I should describe better: these are stationary dots, like half a dozen dead pixels on the left side of the screen. They are there throughout the entire first stage. Would you be willing to take a snap shot of your actual hardware running the game on the first level? It would really help me out a lot to know if it is only my game :)

-Segasonicfan

Edit, I can take a shot of my version too, if someone has a real copy of the game and can tell help me out!

Those dots are as described the points where new color value is written to CRAM. They will be static and always 16 pixels apart on a line (corresponding to VRAM access slots). You see the same thing on SMS and MD games that do midframe palette changes.
The color of the pixel is whatever color is being written to. VDP will read the value written rather than value from CRAM as CRAM is single port and there is no way to delay anything.

Uploaded a video of the problem:

It's the sprite dots flickering in the middle of the screen that follow you. It's super annoying and not in emulation.

TmEE wrote

Those dots are as described the points where new color value is written to CRAM. They will be static and always 16 pixels apart on a line (corresponding to VRAM access slots). You see the same thing on SMS and MD games that do midframe palette changes.
The color of the pixel is whatever color is being written to. VDP will read the value written rather than value from CRAM as CRAM is single port and there is no way to delay anything.

Thanks for the reply TmEE, though it sounds like we are talking about something else. I think you are describing the dots / color movement along the bottom edge of the image, as Sega CD games do and other consoles. I am referring to flickery stuff in the middle of gameplay.

-Segasonicfan

By what mechanism are you getting a full-screen GG image on a monitor?

Sorry for the irrelevant post. That's one nice Amiga monitor you've got in the video! What are you using to connect it to the TV?

segasonicfan wrote

Uploaded a video of the problem:

It's the sprite dots flickering in the middle of the screen that follow you. It's super annoying and not in emulation.

Thanks for the reply TmEE, though it sounds like we are talking about something else. I think you are describing the dots / color movement along the bottom edge of the image, as Sega CD games do and other consoles. I am referring to flickery stuff in the middle of gameplay.

-Segasonicfan

As I wrote before and TmEE is trying to tell you, Gunstar Heroes writes in the middle of the screen to the background colour to get a gradient backdrop, as you can see. Every time the SMS/GG writes to colour RAM (CRAM) in the middle of the screen, you will see this appear as glitches.

It is not a sprite and has no connection to "sprites" whatsoever.

If I remember correctly, when using an Action Replay on the SMS/GG, these write glitches get pushed even further away from the edges of the screen and into the centre.

Thanks for clarifying ccovell, it just looks really strange and is not something I've seen in other GG games and it doesn't appear in emulation. I would still love to hear from someone who has this on GG hardware and experiences the same thing.

As for the TV out, it's the one I built in this thread:
http://www.smspower.org/forums/viewtopic.php?p=54233
That's using viletim's 1 ASIC design. It's hooked up via RGB to the 1084 Amiga monitor

-Segasonicfan

Author	Message
segasonicfan Joined: 05 Jan 2006 Posts: 374 Location: USA	Gunstar Heroes (GG) Sprite Flicker? Posted: Sat Jun 28, 2014 2:42 pm
	Hey all, Recently purchased a Game Gear version of Gunstar Heroes and while it seems to play OK, there is a LOT more flicker and sprite corruption than, say, in this video: Most noticeable is on stage 1, there is a constant (annoying) bunch of light blue "dead spot" pixels that follow throughout on the left side of the screen. These reappear in later levels. Does anyone have a non-emulated version of this game they could check for me to see if my ROM is bad? I would most appreciate it. I tried on 2 Game Gears and the stuff is still there. I wonder if perhaps the GG emulation has something beefed up to help with this. -Segasonicfan

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14745 Location: London	Posted: Sat Jun 28, 2014 3:32 pm
	Most emulators don't apply the sprite limits to get rid of flicker. See if you have an option to enable that (Meka has it) and compare again.

segasonicfan Joined: 05 Jan 2006 Posts: 374 Location: USA	Posted: Sat Jun 28, 2014 4:36 pm
	Thanks for the tip Maxim. I tried the Meka with and without sprite limits now and it still runs AMAZINGLY better than my cart. I would still love it if someone who owns the game could verify what I'm talking about. Seems strange that it should run so different in emulation.

ccovell Joined: 26 Dec 2004 Posts: 374 Location: Japan	Posted: Mon Jun 30, 2014 1:24 am
ccovell Joined: 26 Dec 2004 Posts: 374 Location: Japan	What you may be seeing (blue spots) is the palette colour 0 being changed every scanline to make the gradient on stage 1.

segasonicfan Joined: 05 Jan 2006 Posts: 374 Location: USA	Posted: Mon Jun 30, 2014 6:24 am
	ccovell wrote What you may be seeing (blue spots) is the palette colour 0 being changed every scanline to make the gradient on stage 1. Thanks for the reply. I think I should describe better: these are stationary dots, like half a dozen dead pixels on the left side of the screen. They are there throughout the entire first stage. Would you be willing to take a snap shot of your actual hardware running the game on the first level? It would really help me out a lot to know if it is only my game :) -Segasonicfan

segasonicfan Joined: 05 Jan 2006 Posts: 374 Location: USA	Posted: Wed Jul 02, 2014 12:24 am
	Edit, I can take a shot of my version too, if someone has a real copy of the game and can tell help me out!

TmEE Joined: 31 Oct 2007 Posts: 853 Location: Estonia, Rapla city	Posted: Wed Jul 02, 2014 1:32 pm
	Those dots are as described the points where new color value is written to CRAM. They will be static and always 16 pixels apart on a line (corresponding to VRAM access slots). You see the same thing on SMS and MD games that do midframe palette changes. The color of the pixel is whatever color is being written to. VDP will read the value written rather than value from CRAM as CRAM is single port and there is no way to delay anything.

segasonicfan Joined: 05 Jan 2006 Posts: 374 Location: USA	Posted: Wed Jul 09, 2014 7:32 am
	Uploaded a video of the problem: It's the sprite dots flickering in the middle of the screen that follow you. It's super annoying and not in emulation. TmEE wrote Those dots are as described the points where new color value is written to CRAM. They will be static and always 16 pixels apart on a line (corresponding to VRAM access slots). You see the same thing on SMS and MD games that do midframe palette changes. The color of the pixel is whatever color is being written to. VDP will read the value written rather than value from CRAM as CRAM is single port and there is no way to delay anything. Thanks for the reply TmEE, though it sounds like we are talking about something else. I think you are describing the dots / color movement along the bottom edge of the image, as Sega CD games do and other consoles. I am referring to flickery stuff in the middle of gameplay. -Segasonicfan

Maxim Site Admin Joined: 19 Oct 1999 Posts: 14745 Location: London	Posted: Wed Jul 09, 2014 11:31 am
	By what mechanism are you getting a full-screen GG image on a monitor?

Capt. 2110 Joined: 27 Apr 2014 Posts: 281 Location: Texas	Posted: Wed Jul 09, 2014 1:43 pm
	Sorry for the irrelevant post. That's one nice Amiga monitor you've got in the video! What are you using to connect it to the TV?

ccovell Joined: 26 Dec 2004 Posts: 374 Location: Japan	Posted: Wed Jul 09, 2014 1:53 pm
ccovell Joined: 26 Dec 2004 Posts: 374 Location: Japan	segasonicfan wrote Uploaded a video of the problem: It's the sprite dots flickering in the middle of the screen that follow you. It's super annoying and not in emulation. Thanks for the reply TmEE, though it sounds like we are talking about something else. I think you are describing the dots / color movement along the bottom edge of the image, as Sega CD games do and other consoles. I am referring to flickery stuff in the middle of gameplay. -Segasonicfan As I wrote before and TmEE is trying to tell you, Gunstar Heroes writes in the middle of the screen to the background colour to get a gradient backdrop, as you can see. Every time the SMS/GG writes to colour RAM (CRAM) in the middle of the screen, you will see this appear as glitches. It is not a sprite and has no connection to "sprites" whatsoever. If I remember correctly, when using an Action Replay on the SMS/GG, these write glitches get pushed even further away from the edges of the screen and into the centre.

segasonicfan Joined: 05 Jan 2006 Posts: 374 Location: USA	Posted: Wed Jul 09, 2014 5:54 pm
	Thanks for clarifying ccovell, it just looks really strange and is not something I've seen in other GG games and it doesn't appear in emulation. I would still love to hear from someone who has this on GG hardware and experiences the same thing. As for the TV out, it's the one I built in this thread: http://www.smspower.org/forums/viewtopic.php?p=54233 That's using viletim's 1 ASIC design. It's hooked up via RGB to the 1084 Amiga monitor -Segasonicfan

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