Artificial Harmonic Values not mapped for older GP files

[Danielku15]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

#2667

When importing older GP files, especially GP3, we do not assign the correct harmonic values. This causes a strange display and wrong audio compared to what's the real GP behavior.

Expected Behavior

We should have the same loading behavior as GP8. Notes should be marked as A.H. with the right sounding note / harmonic fret assigned.

Steps To Reproduce

1. Create GP3, GP4, and GP5 files with the available harmonic options
2. Load them in alphaTab
3. Should see the same as in Guitar Pro 8 when opening the same files.

Link to jsFiddle, CodePen, Project

No response

Version and Environment

[AlphaTab][VersionInfo] alphaTab 1.9.0
Logger.ts:24 [AlphaTab][VersionInfo] commit: ac4b6c3f2c862528eabf5c074a4415623e845743
Logger.ts:24 [AlphaTab][VersionInfo] build date: 2026-04-26T17:26:17.977Z
Logger.ts:24 [AlphaTab][VersionInfo] High DPI: 2.1500000953674316
Logger.ts:24 [AlphaTab][VersionInfo] Platform: BrowserModule
Logger.ts:24 [AlphaTab][VersionInfo] WebPack: false
Logger.ts:24 [AlphaTab][VersionInfo] Vite: false
Logger.ts:24 [AlphaTab][VersionInfo] Browser: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/147.0.0.0 Safari/537.36
Logger.ts:24 [AlphaTab][VersionInfo] Window Size: 1778x952
Logger.ts:24 [AlphaTab][VersionInfo] Screen Size: 1920x1080

Platform

Web

Anything else?

GP3 is the main problem format, but I expect similar problems in GP4 and GP5 files. There are various branches for specific versions where the harmonic value might stay unfilled.