This patch has been floating around since the creation of An SMW Central Production, and I feel that now is a great time to add it to the database proper for the convenience of anyone wishing to use it.
What this patch does is, as the name implies, allow you to have multiple music tracks playing on the main Overworld map. This can be very useful if multiple world themes are present, since one track may not fit them all. To set songs, scroll to the bottom of the .asm file and edit the table. Each entry ($XX) represents the song for that particular 32x32 box on the map.
WARNING! It's probably not a good idea to use this if using AddMusic 4.05 due to how it handles music insertion. Doing so may result in a hack that isn't compatible with more accurate emulators. It's best to use this with AddMusicK.
JP32's tutorial is ridiculous. Just set tile grid view to 'on' in the overworld editor and take a screenshot. Then, put the screenshot in paint and draw a black line (holding the shift key) over every 4th line of the grid. You should end up with a 16 x 16 grid which you can label if you need to.
Heres tutorial how to use this, it sound ridiculous but it actually works:
First you need paint.net(and basic knowledge how to use it), take screenshot of OW editor(1x zoom), open it up and crop so that it only shows main map. Now open OWmusic.asm, scroll down and take screenshot of the musicTBL table and crop it so that it only shows Lines 117 to 134(;x0 x4... to last line with db $XX..).
Then do following:
1. Switch back to tab with cropped OW, copy it
2. Switch back to tab with cropped OWmusic.asm
3. Make new layer, paste cropped OW there
4. It asks if you want to make picture larger(or something like that), chose no
5. Select resize tool, now resize the cropped OW picture to fit to the cropped pic of OWmusic.asm
6. Open layer properties on layer with the cropped OW, change mode to multiply and opacity to your liking(you want to see both OW and the OWmusic.asm pictures at same time).
End results should look like something like this(Im using stock OW as an example):
Now the table on OWmusic.asm should make a lot more sense.
Now say for example, you want to change chocolate island to play different music from the rest of the OW? now you just look at this picture:
I highlighted the chocolate island, you need to change all of the "db $XX"'s in OWmusic.asm(asm file, not picture) that are highlighted in red to the song you want it to change to(and the outside regions db's should be the main OW song), make the changes and save&insert the asm file.
Now test it and the music now should change when you are in the chocolate island. This method might not be 100% accurate, but it worked for me and should be easier than pure trial&error.
Well, I did a small mistake while converting the patch that it would break the ROM in case you didn't used SA-1. I fixed that issue. I also optimized a few things by throwing indexes on the code so it makes branches not necessary, thus increasing effectiveness without increasing size.
Also, for the users that have issues with the patch, I worked on a table and a readme so people can know exactly what to do and where to do, so it is a great addition to people who want to use this patch.