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Hi. I'm working on reverse engineering an old game that uses a music format very similar to the Ultratracker ULT files.

Unfortunately, I don't fully understand the ULT format just by looking at the HEX decode and a format specification. I found the point where track instructions start but calculating its length, and thus getting to the audio sample section, turned out to be incorrect. I searched the VLC source code and found the magic string "MAS_UTrack_" but couldn't find anything else relating to the file format (by string search).

Is there some source code in VLC that parses the ULT file I could look at?

Thank you for your time.

Edit: 2023.03.14

With the help of libmodplugin and similar C code, I managed to convert the game file into an ULT file and got (almost) the expected sound. Thank you for the feedback.

Can VLC play your file? Can you share the sample?

VLC can't play the game music.

https://drive.google.com/file/d/16jvS_f ... sp=sharing

The music file format is custom made for the game. It looks very similar to an ULT file, but it has no text and filenames. it has a more compact sample registry, the same pattern-index table, the same track - 1 and pattern - 1 numers, the same pan info. However, the game uses a 6 - byte instruction setup (note, sample, f1, f2, f2_param, f1_param) and is never packed. In contrast, ULT has a 5 - byte instruction map and possible packing. Lastly, the sample bytes are listed.

I documented my findings so far here: https://github.com/akarnokd/open-ig/wik ... ile-Format

I have new information regarding the game's music file XMF.

It is an incarnation of the ULT format, but it also uses the Fast Tracker II command 0x10 - Set Global Volume. Since ULT only allows function 0x0 .. 0xF, I don't know how this command could be represented in ULT.

Also the XMF pattern data is organized as patterns|rows|tracks|instruction . The instruction is (note, sample, f1, f2, f2 param, f1 param).

VLC can't parse trackers per se. It uses libmodplug.