Edit: Whoops I commented on the wrong thread. Not sure how to delete a comment.
Edit: Actually I did comment on the right thread, sorry about that confusion.
This code has a bug. In Koopa Cape, when a brstm is provided that has fewer than 4 stereo tracks, the music volume is doubled. Meanwhile a brstm that has exactly 4 stereo tracks has normal volume. I suspect that this is because in vanilla MKW, in Koopa Cape, the 1st and 4th stereo tracks to play on top of each other at the same time. In order to avoid having double volume when designing a multi track brstm for Koopa Cape, you must leave the 4th track silent.
I suspect what this code does is that when a brstm is found to have fewer than 4 stereo tracks on Koopa Cape, it copies the stereo tracks into any missing channels. This works for Toad's Factory, Wario's Gold Mine, Dry Dry Ruins, Moonview Highway, and Bowser's Castle. But it doesn't work for Koopa Cape. Because the 4th stereo track plays at the same time as the 1st, resulting in double volume when those tracks are playing.
The fix for the developer would be to make a special case for Koopa Cape, which creates a 4th stereo track for the brstm, but fills it with silence instead of a duplicate of the 1st stereo track.
A temporary fix for users is that you can make any single-channel brstms that you intend to use on the KC slot half volume. However, this is not ideal if you have lots of brstms for a custom track distribution and you may end up changing the slot that a brstm plays on. If you decide to switch a brstm to another slot, then you will have to make its volume normal. Another side effect is that the brstm volume will be half when you collide with sound triggers that normally switch to the 2nd or 3rd stereo tracks.
Another fix is to edit the brsar and cut the volume of the KC slot in half. Now any brstms you place on the KC slot will automatically have their volume un-doubled without you needing to edit each and every one of them. However, this still isn't ideal because now any multi-channel brstms that you want on the KC slot will be at half volume. You can either make your multi channel brstms for KC twice as loud when you are making them in Audacity (which isn't ideal, there will be sound clipping, even if you use the Limiter instead of regular amplify) or you can use the "Music Volume can be set via BRSTM" code that is used in CTGP to double the volume without sound clipping. However, that code isn't public, so good luck getting ahold of it.
Edit: Actually I did comment on the right thread, sorry about that confusion.
This code has a bug. In Koopa Cape, when a brstm is provided that has fewer than 4 stereo tracks, the music volume is doubled. Meanwhile a brstm that has exactly 4 stereo tracks has normal volume. I suspect that this is because in vanilla MKW, in Koopa Cape, the 1st and 4th stereo tracks to play on top of each other at the same time. In order to avoid having double volume when designing a multi track brstm for Koopa Cape, you must leave the 4th track silent.
I suspect what this code does is that when a brstm is found to have fewer than 4 stereo tracks on Koopa Cape, it copies the stereo tracks into any missing channels. This works for Toad's Factory, Wario's Gold Mine, Dry Dry Ruins, Moonview Highway, and Bowser's Castle. But it doesn't work for Koopa Cape. Because the 4th stereo track plays at the same time as the 1st, resulting in double volume when those tracks are playing.
The fix for the developer would be to make a special case for Koopa Cape, which creates a 4th stereo track for the brstm, but fills it with silence instead of a duplicate of the 1st stereo track.
A temporary fix for users is that you can make any single-channel brstms that you intend to use on the KC slot half volume. However, this is not ideal if you have lots of brstms for a custom track distribution and you may end up changing the slot that a brstm plays on. If you decide to switch a brstm to another slot, then you will have to make its volume normal. Another side effect is that the brstm volume will be half when you collide with sound triggers that normally switch to the 2nd or 3rd stereo tracks.
Another fix is to edit the brsar and cut the volume of the KC slot in half. Now any brstms you place on the KC slot will automatically have their volume un-doubled without you needing to edit each and every one of them. However, this still isn't ideal because now any multi-channel brstms that you want on the KC slot will be at half volume. You can either make your multi channel brstms for KC twice as loud when you are making them in Audacity (which isn't ideal, there will be sound clipping, even if you use the Limiter instead of regular amplify) or you can use the "Music Volume can be set via BRSTM" code that is used in CTGP to double the volume without sound clipping. However, that code isn't public, so good luck getting ahold of it.