Revisiting this after seeing Bob’s review of the RetroTINK 2X for RetroRGB.
…there are very interesting mods out there that add HDMI to some of the most relevant consoles. UltraHDMI for N64 and GCVideo for GameCube are quite interesting indeed!
However, those cannot be used over an OSSC, which is a real pity, due to the lack of DVI/HDMI input.
They can! But not directly. You need to use an active HDMI to VGA converter, like this one from Tendak. (I believe it’s this one that people were talking about on Shmups; someone correct me if I’m wrong.) I’m not sure which one Bob used in his video, but the one he tested proved to be lagless and worked perfectly fine with the OSSC.
So, something like the UltraHDMI can be run through one of these HDMI to VGA converters, into AV3 on the OSSC. The UltraHDMI in particular has a Direct+Sync mode that can be enabled that simply passes through the video in the original resolution and at the original framerate with no processing or normalization, to which the OSSC can apply its processing. (If your display doesn’t like the original framerate, you can always try the regular Direct mode.)
However, HDMI is quite better than any analog solution.
This is generally true. The only problem I’ve seen with HDMI solutions is video dropouts/resyncs from mode switching, which you won’t see with CRTs, on which these games were originally intended to be played. This is typically only a problem for 5th- and 6th-generation consoles, which often used a higher-resolution interlaced mode (480i) for menus and title screens, then switched to a lower-resolution progressive mode (240p) for gameplay. You can also get dropouts when transitioning from these consoles’ boot menus/operating systems to a game that supports ED or HD resolutions, such as the Xbox and PS2, which output in 480i on boot, and then switch to a higher resolution where supported/enabled by a game.
There are also some HDMI mods which just output 480p video like the Akura
Yes, but, unlike the Akura, or that PS2 HDMI mod, and possibly that Xbox HDMI cable (I don’t know which audio it taps), a native HDMI mod has the capability to directly source the original digital audio, instead of converting analog to digital. Sure, it’s only stereo, but, when it can be tapped before hitting the DAC, you won’t have any of that analog noise floor hiss.
Unfortunately, there will be consoles where tapping digital audio isn’t feasible. The only console I’m aware of where this is the case is the Famicom/NES, where Expansion Audio is concerned. My understanding is that Expansion Audio carts feed their audio to the console as analog; so, I imagine any completely-digital Expansion-Audio-capable NES/Famicom would first need the cartridge modified with a coax dongle/port providing S/PDIF (probably makes the most sense to add this to an EverDrive N8, versus modifying original carts), and then the console would need to be modded with an S/PDIF coax input, which would be wired to a theoretical expansion audio input on a Hi-Def NES, where it would get mixed like the original hardware does with the analog audio. Sorry; tangent.