Ok, so having finally managed to get it working, here's a step-by-step guide, since there isn't any documentation out there on the implementation details of the msu-1 in higan, e.g. the manifest markup or the file naming scheme. Thankfully, byuu helped me figure it out, so I'll pass it along here.
First of all, open higan and import your Zelda ROM. This should create a game folder inside [user home folder]\Emulation\Super Famicom. If you also want to have a non-MSU version in your higan library, make a copy of the game folder and rename it whatever you want in order to differentiate the two.
Now, use LunarIPS (or any other IPS patching tool) to apply the IPS patch in the release folder from that link (see the "Getting Started" page for a download) to apply the patch to the file named program.rom inside the game folder. Create an empty file inside the game folder named msu1.msu. Note that if you do this, you *don't* need to copy all of the files from the release package into the game folder.
Then, edit the manifest.bml, changing the title (if you want), the sha256 hash, and also adding the following lines:
Code:
msu1
rom name=msu1.msu size=0x0000
map id=io address=00-3f,80-bf:2000-2007
Or, if you prefer, here's my full manifest.bml file
Code:
cartridge region=NTSC
board type=1A3B revision=11,12,13
rom name=program.rom size=0x100000
ram name=save.ram size=0x2000
map id=rom address=00-1f,80-9f:8000-ffff mask=0x8000
map id=ram address=70-7d,f0-ff:0000-ffff
msu1
rom name=msu1.msu size=0x0000
track number=1 name="01 Title - Link to the Past.pcm"
track number=2 name="02 Hyrule Field Main Theme.pcm"
track number=3 name=""
track number=4 name=""
track number=5 name="05 Forest of Mystery.pcm"
track number=6 name=""
track number=7 name="07 Kakariko Village.pcm"
track number=8 name=""
track number=9 name="09 Dark Golden Land.pcm"
track number=10 name="10 Unsealing the Master Sword.pcm"
track number=11 name="11 Beginning of the Journey.pcm"
track number=12 name=""
track number=13 name=""
track number=14 name="14 Guessing Game House.pcm"
track number=15 name=""
track number=16 name="16 Majestic Castle.pcm"
track number=17 name=""
track number=18 name="18 Dank Dungeons.pcm"
track number=19 name=""
track number=20 name="20 Safety in the Sanctuary.pcm"
track number=21 name=""
track number=22 name=""
track number=23 name="23 Fortune Teller.pcm"
track number=24 name="24 Dank Dungeons.pcm"
track number=25 name=""
track number=26 name=""
track number=27 name="27 The Goddess Appears.pcm"
track number=28 name=""
track number=29 name=""
track number=30 name=""
track number=31 name=""
track number=32 name=""
track number=33 name=""
track number=34 name=""
track number=35 name=""
map id=io address=00-3f,80-bf:2000-2007
information
title: The Legend of Zelda: A Link to the Past (MSU-1)
name: Legend of Zelda - A Link to the Past (MSU-1), The
region: NA
revision: 1.0
board: SHVC-1A3B-12
serial: SNS-ZL-USA
sha256: e975381a0a07ba655469b2384e1c8a9f00f814a6c46468dcfa4e1f3ae96c9639
configuration
rom name=program.rom size=0x100000
ram name=save.ram size=0x2000
Notice all of the track number=x name="" lines. These can be deleted if you want, in which case the .pcm files should be named track-1.pcm, track-2.pcm, etc. If you leave those lines there, you can name the music files whatever you want and just put the file name in the manifest (as you can see, I'm just getting started). The .pcm files go inside the game folder (i.e. in the same folder as manifest.bml, program.rom, msu1.msu, etc).
Now to convert the audio files. First you need to convert whatever source files you have into 16-bit, 44100 PCM .wav files. Once you've done that, you can use the wav2msu program in the release folder you downloaded previously to add the required msu header. Copy the files into the game folder and name them appropriately (and update the manifest if necessary), and you should be good to go. Use the
track list to get an idea of what song is what track number (NB, the songs at the beginning with the rain sound effect during the storm seem to be separate tracks, and I can't find their track index just yet). My suggestion is to start with the title track to be sure that you actually have it working before starting to work on the rest of the tracks.
There are a few issues with that patch, so I'm not sure if you actually want to work on the .asm to improve it or if you were just looking for a drop-in solution. For one, if you're missing a track and it falls back to the original .spc, it doesn't properly stop the .spc track when it switches to a new track that does have a .pcm replacement (e.g. try replacing the file selection song without replacing the title track, you'll see what I mean). Also, opening the map completely breaks all audio, and you just get white noise. Not sure what's up with that. There may be other bugs too, but that's what I found in about 20 minutes playing around with it.
Anywho... there ya go. Have at it. And if you do happen to improve the patch to fix some of the issues (I've read elsewhere that track fading probably isn't handled, so that probably needs to be added), please go ahead and release your improvements