https://archive.org/details/the-cd-graphics-world-by-extended-graphics I think that this is the first dump of a CD+EG disc. I tested it with the PC-FX core on Mednafen, but I couldn't get it to work with the Saturn core (might just be me!). I haven't tested it with any other Saturn emulators. I also tested it on Mega-CD in Ares (CD+G backwards compatibility). https://patents.google.com/patent/US5426516A/en Lots of karaoke software supports CD+G, none support CD+EG, so there is very little technical information about this format. The link above is Victor's patent on it from 1991. Basically it supported storing two images at a time, so you could smoothly transition from one to another (and back and forth if required), whereas CD+G had to slowly overwrite the existing image. It could also combine the colour palette from two images in order to increase the on-screen colours from 16 to 256. As far as I can tell the only major publisher to support it was Victor, although it was also supported by some smaller publishers, such as this Bingo game. I don't think that this format ever left Japan, I did buy a western CD with the logo on it, but it had no data. Maybe the Japanese version has it, but as the CD was from 2017 I suspect they just used the wrong logo. I have a more interesting release on the way, but with how long the last one took that might be a month away. Here's some images from CD+G mode on a Mega-CD through Ares on the left, and CD+EG mode on a PC-FX through Mednafen on the right. I suspect the emulation isn't perfect, there's some artifacts which aren't displayed on the cover images. I resized to 480 x 360 as the emulator screenshots output some wacky aspect ratios.
Oooh, nifty - I'm amazed any emulator can run CD+EG, given there hasn't been any disc dumps. Mednafen's Saturn core doesn't do CD+G, likely due to lack of demand. Maybe someone needs to push that issue.
To be honest I expected it to work as it's all done by the bios rather than the emulator. I guess the Saturn core could easily support it, but a lot of emulators are only focused on playing games rather than other niche uses. Track 6 on that CD is from Dungeon Master (specifically the Super Famicom version), and it's a pretty cool use of CD+G, using palette cycling to create the illusion of movement. I looked it up and it's from this disc, which someone helpfully dumped and uploaded Youtube videos for. It's from a CD+G disc which accompanied the SFC release, which is ironically playable on Sega and NEC systems, but not Nintendo. The back cover mentions PC-Engine CD-ROM and FM-Towns. It released just after Mega-CD, so I guess it was finished before they knew they could put that on the compatible hardware. I recommend watching the videos, it's one of the better uses for CD+G that I've seen. Unfortunately the disc has been converted to MP3+CDG karaoke software files. I might be able to convert it back to a disc image, but how accurate to the orginal will that be? Would Redump accept that? I doubt it, but luckily they've already dumped it, but without the sub-channel data! That blows my mind, isn't the whole point of Redump to accurately redump stuff that previously wasn't dumped properly? I think ~5% of an audio CD's capacity is reserved for the sub-channels, so how do you know there isn't any data there (a lot more formats used it than just CD+G) without dumping it? In this case it's even worse as it's clearly labelled on the box. /end rant.
