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Summary

Gsfopt is possible to write wrong value to ROM coverage in gsflib optimization (mode -l for instance). The condition to cause the glitch might not be very common, but it might wipe the ROM data (especially a sample) quite slightly without being noticed.

How to fix : If you worry about gsflibs that you have optimized by old gsfopt, redo the gsflib optimization with unoptimized ROM, then replace your gsflib to new one.

Here I can provide a special build of gsfopt 1.2.8, which can indicate the possible ROM offset which gets erased wrongly. gsfopt-1.2.8-win32-overflow-indicator.zip

Occurrence condition

The mechanism of the glitch is simple. It's too stupid.

u8 * rom_coverage;
u8 * another_rom_coverage;

for (u32 offset = 0; offset < size; offset++) {
    if (rom_coverage[offset] + another_rom_coverage[offset] <= 0xff) {
        rom_coverage[offset] += another_rom_coverage[offset];
    } else {
        rom_coverage[offset] += 0xff; // wait, why += is placed here
    }
}

In words: the glitch occurs when the song A refers to a certain address once, and another song B refers to the same address at least 255 times.

Screenshot

I have found the glitch since gsfopt destroyed a certain instrument of Juka and the Monophonic Menace BGM 7.

Using the export to ROM feature on the GSFs for Di-Gi Charat: Digicommunication and DigiCommunication Nyo: Datou! Black Gemagema Dan seems to cause the Nintendo logo check to fail. I'm not sure why this happens. Meanwhile I have converted a GSF from the soundtrack of Mother1+2 GBA and the logo check passes, playing fine. Is there a reason this happens?

Greetings! :)
My apologies for reporting the same issue as user UnforeseenOcean, but their post is now more than a year old and still has not received any answer. So this is really nothing more than a shot in the dark, hoping for a long awaited solution.

Exactly as previously described, when converting a .gba ROM into a .gsf file with rom2gsf [version 1.0], and then trying to process that .gsf output through gsfopt (using ###-T [10:00.000] -f [gsf file here] file.gsf### ) , the error code ###Error: [gsf file] - File size error### appears.
I'm afraid that I'm utterly at a loss, and can't understand what went wrong and, most importantly, what I should do to in order to make this program function properly.

I truly wish for this post not to go unnoticed..
But, in any case, I sincerely thank you, loveemu, for taking the time to read this message (if that's the case X)), but also for your hard and relentless work on the GBA's convoluted sound formats
May everyone have a magnificent day! :)

Input: 1728 - Grand Theft Auto Advance (U)(Mode7).gba (I am only looking for the intro tune)
Output: File that does play but is abnormally large and also fades out after 3 minutes

All of the files result in Error: 8 - File size error.