Reply To: Overscan, AR, shaders and overlays

[patrickm]

[quote=100421]Hello there!

I’m having some difficulty understanding the myriad of different ways you can effect the video signal in retroarch and emulationstation. I’m mainly concerned here with 8bit and 16bit emulators (so gameboy, NES, SNES, Master System, Megadrive etc) and I would like to get them looking retro with a decent scanline shader that doesn’t cause a performance hit, as well as border overlays for each console.

I’m using the following:

RPi2 overvlocked to ‘pi2′ setting
RetroPie 3.0 (beta 4)
Samsung 720p televison

Overscan

First issue I have is with overscan. Now, I don’t really know what it means, but I understand that if I start messing with the values in /boot/config.txt such as

overscan_left=16
overscan_right=20

it alters the size of the black borders around the display. I’ve managed to get this to a point where the black borders are no longer an issue (i.e. the terminal and emulationstation’s gui fit nicely within the whole area of my tv), but I’m worried that doing this is going to effect how retroarch uses the display. Is this something I need to worry about or is tweaking those values good practice regardless?

Should I instead force retropie to always use 720p as that is the native resolution of my display and is never going to change? I believe this is possible by going into the aforementioned config file and declaring the following:

hdmi_group=1
hdmi_mode=4

but I’m not sure if that’s correct. If I force a 720p resolution in that manner, do I need to disable overscan explicitly or just ignore it?

If I’ve explicitly configured an emulator (e.g. snes9xnext) to run at 720p, using the x button as it boots the rom to apply a custom configuration, does it even matter what I force my resolution to?

Aspect ratio, Shaders & Overlays

I’ve been playing with the shaders + border style overlays you can use in retroarch. Whilst I understand the basic principle, I’m having some difficulty knowing what’s best to use, especially when it comes to aspect ratio. For simplicity’s sake I just want to get decent looking scanlines for the 8-bit/16bit consoles without having a performance hit, and also use some nice borders to fill in the black bars at the side on a per console basis, bearing in mind I’m locked to a 720p display.

Consoles will be 4:3, and handhelds like the gameboy use their own weird AR’s that I’m not familiar with. This is where things start getting murky, because retroarch has so many video settings and shader options that I really don’t know where to begin. I have no idea what ‘integer scaling’ is for example, and various different forums I’ve viewed all say different things “turn it ON always/turn it OFF always” etc. I’ve no idea if I should force an aspect ratio (e.g. 4:3 for the SNES) or use a custom one (which I can’t seem to customise in RGUI).

I’m using borders from here and the default shaders that come with retropie. I’ve managed to load shader presets on the snes9xnext emulator and it looks alright from what I can tell, however I have no idea if I’m doing it right, because I’m not sure what to set the other settings to.

Can anyone offer some advice? I did look through some of the other posts in this very forum but I found it a bit overwhelming and most people seem to deal with 1080p displays.

[/quote]

I don’t understand why you don’t just use shaders. CRT-Hyllian or CRT-Caligari look quite nice and run smooth at 720p on the pi 2. Set RA to use your native display res, always.

If you really want to use overlays, what you are interested in can be found in “how to get perfect video scaling” and “how to get scanlines.”

Yes, you should tell RA to always use your native display resolution. Doing otherwise results in scaling artifacts and input lag.

You can’t get a perfect 4:3 aspect ratio for consoles on a fixed-pixel display without it resulting in scaling artifacts. You can hide these with shaders, though.

On a more powerful machine, you can use the sharp-bilinear or pixellate shaders to force a 4:3 ratio and hide the scaling artifacts, but it will cause a performance drop on the pi 2.

I believe I provided a link to a 3x scanline overlay for use with 720p displays in one of those two threads, but here it is again:
https://www.dropbox.com/s/0aae6uwxfl7di48/scanlines1280x720.png?dl=0

Here is also an aperture grill overlay I made for the same resolution, although its really a grid at this resolution:
https://www.dropbox.com/s/bopljr1git0x9dt/aperturegrill1280x720-3x.png?dl=0