Neo Geo CD Audio / Emulator Compatibility Issue

[Maximus734]

Hi,

I have been testing Neo Geo CD CHD mounting with different emulators and wanted to report some compatibility issues.

FinalBurn Alpha (FBA64 v0.2.97.43)

CUE/ISO (/s:22)

• Game loads correctly.
• CD music does not play.

FBA requires WAV audio tracks for Neo Geo CD music.

CUE/ISO/WAV (/s:24)

• Neo Geo CD BIOS loads.
• The game does not start.

---

Nebula

Neo Geo CD (/s:5)

CHDMounter mounts the CHD successfully.
Nebula can run the game when launched directly (nebula neocd or loading Neo Geo CD).
However, the mounted drive does not appear in Nebula's Emulation → Load NeoGeoCD Drive selection menu.

For comparison, using CHDMounter CUE/BIN output mounted through DAEMON Tools:

The drive appears correctly in Nebula's Neo Geo CD drive selection menu.
The game launches.
CD audio plays correctly.

I compared the mounted drives:

CHDMounter Neo Geo CD mount:

Volume in drive Z is Xeno Crisis (World) (Unl)

DAEMON Tools mounted CUE/BIN:

Volume in drive Z is XENOCRISIS

The disc contents are accessible in both cases, but Nebula detects the virtual CD differently. This may indicate a difference in how the mounted filesystem exposes CD-ROM information or Red Book audio tracks.

Thank you

[drpetersonfernandes]

OK. I will investigate.
Thank you for testing it.

[drpetersonfernandes]

Hi @Maximus734, thank you for the detailed report. I've investigated all three points — two were genuine bugs that are now fixed, and one is a platform limitation worth explaining.

1. FBA CUE/ISO — "CD music does not play"

Confirmed and fixed. In CUE/ISO mode the generated .iso was missing all audio tracks: the CUE listed TRACK 02..54 AUDIO inside the file, but the file content ended after the data track, so every CD audio read hit end-of-file. FBA loaded the game (the data track was intact) but had no audio to play. The ISO now contains the audio tracks at the correct sector size, with the declared file size matching the content.

2. FBA CUE/ISO/WAV — "BIOS loads, the game does not start"

Confirmed and fixed. This was the same root cause as the audio timing issues in issue #1: track offsets were shifted by the pregap length. The WAV files for tracks after the first were built from the wrong sectors — each contained the wrong audio at the tail, and the last track was truncated (its declared size was larger than the readable content). Emulators that rely on the WAV content/timing could fail during boot. I've corrected the offsets and the WAV export; with the fix, the game boots normally and the audio tracks play at the correct positions.

3. Nebula — the mounted drive doesn't appear in "Load NeoGeoCD Drive"

This one isn't a defect in the mounted filesystem — it's how Nebula enumerates drives. Nebula's drive selection menu scans for physical CD-ROM devices (the SCSI/IDE CD-ROM class). A Dokan/WinFsp virtual mount is a generic disk drive, not a CD-ROM device, so it can't appear in that list. DAEMON Tools works because it creates a real virtual CD-ROM device. No CHDMounter-side change can make a virtual filesystem drive show up as a CD-ROM device — that would require a different mounting technology.

For Nebula, the practical options are the direct-launch path you already found works (nebula neocd / loading the Neo Geo CD), or mounting the extracted CUE/BIN with a tool like DAEMON Tools.

Volume label

The mounted volume label comes from the CHD filename (e.g. "Xeno Crisis (World) (Unl)") rather than the disc's internal label. It's cosmetic and doesn't affect Nebula's detection, but I'll consider deriving it from the disc's own volume name in a future update.

Both fixes are verified against the Xeno Crisis and Metal Slug CHDs on the Dokan and WinFsp variants and will be in the next release. Thanks again for the thorough report!

[drpetersonfernandes]

I did some tests

Final Burn Alpha (accept cue and iso)

cue/iso-2048
CUE No
ISO Yes without music

cue/iso/wav-2048
CUE Yes with music
ISO Yes without music

cue/iso-2352
CUE No
ISO No

cue/iso/wav-2352
CUE No
ISO No

Final Burn Neo (accept ccd and cue)

cue/iso-2048
CUE No

cue/iso/wav-2048
CUE No

cue/bin-2048
CUE No

cue/bin/wav-2048
CUE No

cue/iso-2352
CUE Yes with music

cue/iso/wav-2352
CUE No

cue/bin-2352
CUE Yes with music

cue/bin/wav-2352
CUE No

Nebula (accept cue and iso)

cue/iso-2048
CUE Yes without music
ISO Yes without music

cue/iso/wav-2048
CUE Yes without music
ISO Yes without music

cue/bin-2048
CUE Yes without music

cue/bin/wav-2048
CUE Yes without music

cue/iso-2352
CUE No
ISO No

cue/iso/wav-2352
CUE No
ISO No

Raine (accept cue)

cue/iso-2048
CUE Yes with music but with graphic glitches

cue/iso/wav-2048
CUE Yes with music

cue/bin-2048
CUE Yes with music but with graphic and audio glitches

cue/bin/wav-2048
CUE Yes with music

cue/iso-2352
CUE Yes with music

cue/iso/wav-2352
CUE Yes with music

[drpetersonfernandes]

NEW VERSION WITH THE FIXES

https://github.com/drpetersonfernandes/CHDMounter/releases/tag/release_1.2.0

[Maximus734]

Hey drpetersonfernandes, awesome to hear CHDMounter has been fixed! I downloaded the Dokan version since that was the default used with Simple Launcher.

Thanks for the explanation regarding the Nebula setup with neocd. So, for Nebula, the current workaround is to use CHDMounter to create the CUE/BIN output, mount that through DAEMON Tools as a virtual CD-ROM, and then load the game in Nebula.

I also did a small test with Metal Slug and Xeno Crisis using FinalBurn Alpha:

Xeno Crisis — CUE/ISO/WAV 2048: CD music has glitches. During the intro, the audio cuts out and then appears to restart, causing synchronization issues afterward.
Metal Slug — CUE/ISO/WAV 2048: Appears to work correctly so far.

I'll do more testing when I have time, including Raine and the RetroArch FBNeo core since those have CHD support.

I also discovered a couple of things:

FinalBurn Neo standalone has native CHD support in the nightly builds.
Nebula can load Neo Geo CD games directly through Load NeoGeoCD ISO using CUE/ISO images with MP3 audio tracks. I tested Metal Slug and the game launch with CD music when the required MP3 tracks are present.

Thanks again for the update and for looking into the issues!