A mod I made as a sort of test or proof of concept that proves a dynamic BGM mod can be made and (sorta) work. The transitions could be a lot
smoother and they don't all start/end on good loop points but due to my lack of sound editing skills, I wasn't sure what to do about that. Thankfully this song was already a boss fight theme which had multiple phases and segments meant to be looped so that made my job easier even if I still could've done better.

I know it sucks and that it can be done better but I don't really feel like working on this anymore so I'm just gonna leave it as is. I just haven't seen many, if any, other mods something like this (at the time I'm writing this) so I figured I might as well upload an attempt at dynamic BGM modding.

Installation Instructions:
Download the mod and place the .zip file in the "Games\SF6\Mods" directory within Fluffy Mod Manager.

At least for Zangief's theme, it's divided between 7 WEM audio files in natives\stm\streaming\product\sound\wwise\bgm_battle_esf006.spck.1.x64

Wem ID and when it plays:

37368176 = Final Round
135294031 = Between Rounds (Round transition music)
198767430 = It's the ending of the song but I'm not sure when you'd ever hear this.
358277792 = The regular music that plays whenever there's no conditions like low health, nearing timeout, or being in the final round at play. (Non-final round BGM)
436810252 = The segment of the song that plays during the match intros and before the first round call. (Intro BGM)
584908543 = The theme that plays after the round transition BGM. Once this finishes playing, it transitions into the non-final round BGM about 17-18 seconds into it. (Round 2 theme that transitions into non-final round theme)
910677074 = Segment of the BGM that plays when the round timer is at 10 seconds left or if one of the characters is at low health. (Low health/near timeout BGM)

I had to replace the pck files "bgm_battle_esf006.spck.1.x64" in both "natives\stm\streaming\product\sound\wwise" and "natives\stm\product\sound\wwise". And just in case, I replace the tiny segment of the intro that plays in the audio file contained within the sound bank, "bgm_battle_esf006.sbnk.1.x64".

Outside of that sound file, I didn't touch any of the HIRC data in the sound bank. I just worked around the existing loop points and fade outs instead of altering them to fit the modded song. There's probably a way to do this but the method of doing it is even more tedious and time consuming than the way I did it. Not to mention, I've never been able to get my xml file edits to work since it's too complex for my tiny brain to handle correctly.

But if one were able to get those xml changes to work, I think it'd make the theme swapping alot more flexible since it's not working around pre-existing .bnk file data. So thus a simple rename of the WEM files and the PCK/BNK files would be the only thing that would be needed to make it swap a different theme, if I understand the process correctly (which I probably don't).

Let me know if there are any issues getting the music to actually play. Because I already know about the issues of how bad the transitions are.

Also, I wanna clarify that I do like Zangief's theme in this game alot. I simple chose to work with his theme because it's the one I know the best.