Oracles Music Format

[Lin]

Well, I decided to dive into the wonderful world of music in Oracle of Ages, and I've been studying the format for a little bit, and here's what I have so far.

First off, music pointers (and I suppose sound) are stored at 0xE5748 and each music pointer gets 3 bytes. The first byte is the bank - 0x39, so whatever is there add to 0x39. The next 2 bytes are the actual pointer and point to the instrument headers. From there, there are 3 bytes per channel (4 channels), so 12 bytes total. I'm not sure what the first byte does, but the next 2 bytes point to the music data using the 0x39 + x as the bank. Here's what I know about the music header:

Anything under E0 is a note, following this format:
-Note pitch (Byte) Only seems to go up to 40
-Note length (Byte)

From E0-EF is an instrument effect that uses this format:
-First 3 bits of the Ex is the effect, although they seem to be a fade-in
-Effect length (byte)
For example, E0 will fade in to the next note and I guess last the length byte's length

From F0-FF is a special code that references different assembly. Here's my table so far:
F0 = ?
F1 = ?
F2 = ?
F3 = ?
F4 = ?
F5 = ?
F6 = Set instrument (Next byte), Set Volume (Next byte, although the right nybble controls volume. I don't know what the left does)
F7 = ?
F8 = ?
F9 = Set Vibrato (Next byte)
FA = ?
FB = ?
FC = ?
FD = ?
FE = ?
FF = End

I'll surely be updating this more, and when I've got it all figured out I'll make a tool that edits music and can export/import music from Seasons and vice-versa.

~Lin

[Jigglysaint]

One of those pointer bytes is a relative bank pointer.  You can place data anywhere beyond that first bank, but nowhere before it.

[Lin]

I already knew that, and tried it for the first byte in the 4 pointers for the instruments, but they never led to the data, so it seems only the first byte is the relative bank pointer, which I pointed out in the topic.

[Jigglysaint]

Well from what I tested, for the 4 channels, the first byte, if changed, seems to cause the music to "mix".  For example, if you changed the second channel of the overworld music from 01 to 00, you will hear one of the channels from the previous song in ram start playing during the song.  It seems all the channel pointers have the same pattern for the first byte.  00, 01, 04, and 06.

[Lin]

Yeah I noticed that. That's what confused me at first. I think the values might be hardcoded to be specific values that need to be written to some sort of registers, because if any of the values are wrong then music stays glitched until the game is restarted.

[jerrythomas]

I have tried this but did not succeeded , if you have got positive results please do share.

[Luigi1000]

Well this idea does proove to be intresting topic to go about as it can bring an intresting change to the hacks. Will try to get what info I can.