best video for retro games from hdmi source

[primeform]

Im building an emulation computer based on a Raspberry Pi. It only has an HDMI out and I would like to get the best possible experience for the old games on new LCD screens. Do i need a Scan Line Generator? Should I use a HDMI - VGA converter into and SLG? Would I need to scale it to go back to HDMI again? What resoultion should I put out via the HDMI? Does this stuff make anyone elses brain hurt?

[Xyga]

If it's emulation you don't need an SLG, just apply fake scanlines filters/effects from the emulators's options. Most emulators feature pretty decent filters/shaders for this.
The kind of setup you're thinking about is kind of useless and way overkill.

PS: Avoid screens with a low vertical resolution. 1080 is a bit small for advanced scanlines engines like Mame's HLSL. Try to pick one with 1200 or 1440. I don't know if the Rapsberry Pi can handle this though...

[beatsgo]

^ what he said. If you don't like the emulated scanlines, you can do a HDMI to VGA converter -> SLG3000 -> LCD Monitor setup.

[primeform]

I was worried about the quality of the shaders. Is there a thread that compares the quality of SLG3000 to emulator shaders? seems like alot of hassle to convert to vga, then back up to hdmi again to run the slg tho. Wish there was and HDMI > HDMI slg. I read a post where Fudoh said he likes 480p output on 1080 screen tho most for closest to CRT emulation. Does that require an upscaler? Would the emulator shaders still look good?

[Xyga]

That depends on the emulator and what's available but basically emulators do a better job.

Mame current builds: HLSL -> much more advanced than anything else but kind of power-hungry and difficult to set up.
Mame up to v0.106: old scanlines management up -> looks somewhat like your average XRGB/SLG stuff
Kega Fusion: Scanline TV filter plugin -> same
ZSNES: NTSC effect settings -> again XRGB/SLG (when set to RGB)
ePSXe: Pete's OGL2 plugin -> very nice scanlines possibilities, but you have to know how to do it (most people don't)
SSF: filter plugins -> much like Kega

Etc, etc... it's possible to get scanlines on most emulators without much hassle and output at your screen's native resolution, only HLSL is a bit complicated, and OGL2 might not work on the Pi (don't know but usually this requires a genuine AMD/nVidia graphic chipset).

If you really insist on using an SLG you'll have to force your emulators to output 480p indeed, but I don't know why you would insist on reconverting to HDMI, you could easily do what beatsgo suggested...
... or did you forget to tell us that your display doesn't have a VGA input ? Are you planning to use TV ?

Don't bother buying an external scaler for emulation, that would be ridiculous.

[primeform]

Ok going to stick to the emulator shaders for scan lines. Thanks for the response. Unfortunately I still need to extract audio from the HDMI to run some speakers.

[Xyga]

Don't hesitate to ask if you need tips on how to set up emulators for scanlines, or simply find the required files.

For HLSL there's a great thread here: http://shmups.system11.org/viewtopic.php?f=6&t=45026

[beatsgo]

Ok going to stick to the emulator shaders for scan lines. Thanks for the response. Unfortunately I still need to extract audio from the HDMI to run some speakers.

The RPi has a 3.5mm stereo audio jack, no point of extracting the audio from the HDMI line.