[MP2K][Bug Report] Tune calculation when saving to MIDI

[laqieer]

5a85cda

[Kermalis]

Hi, does this still keep the MIDIs matching? As in, does the midi produce a matching asm output with mid2agb?

The current midi exporter matched all MIDIs for the 5 main series Pokémon games, so as long as this tune modification is an actual fix then it's accepted. I don't remember if they used tune at the moment

Other enhancements to the midi exporter won't be accepted right now since there's no way to toggle the output type (matching or enhanced) with a dialog

[laqieer]

The expoted midi doesn't match without the bug fix. As in, it produces a mismatching asm output with mid2agb.

Here is an example: FireEmblemUniverse/fireemblem8u@4b87e79

1. 64 is subtracted for TUNE before:
   

   VGMusicStudio/VG Music Studio/Core/GBA/MP2K/Player.cs

   Line 331 in 3a628c5

   AddEvent(new TuneCommand { Tune = (sbyte)(cmd - 0x40) });

   
   

   VGMusicStudio/VG Music Studio/Core/GBA/MP2K/Player.cs

   Line 552 in 3a628c5

   AddEvent(new TuneCommand { Tune = (sbyte)(tuneArg - 0x40) });

2. But it is not added back later:
   

   VGMusicStudio/VG Music Studio/Core/GBA/MP2K/Player.cs

   Line 845 in 3a628c5

   track.Insert(ticks, new ChannelMessage(ChannelCommand.Controller, trackIndex, 24, tune.Tune));

   
   While it is added back at the same time for PAN and BEND:
   

   VGMusicStudio/VG Music Studio/Core/GBA/MP2K/Player.cs

   Line 803 in 3a628c5

   track.Insert(ticks, new ChannelMessage(ChannelCommand.Controller, trackIndex, (int)ControllerType.Pan, pan.Panpot + 0x40));

   
   

   VGMusicStudio/VG Music Studio/Core/GBA/MP2K/Player.cs

   Line 808 in 3a628c5

   track.Insert(ticks, new ChannelMessage(ChannelCommand.PitchWheel, trackIndex, 0, bend.Bend + 0x40));

3. 64 is subracted from the value for TUNE, PAN and BEND:
   https://github.com/pret/pokeemerald/blob/ef4d99c87e898f34be793fe72bef8f3f3cf2fcb2/tools/mid2agb/agb.cpp#L393
   https://github.com/pret/pokeemerald/blob/ef4d99c87e898f34be793fe72bef8f3f3cf2fcb2/tools/mid2agb/agb.cpp#L360
   https://github.com/pret/pokeemerald/blob/ef4d99c87e898f34be793fe72bef8f3f3cf2fcb2/tools/mid2agb/agb.cpp#L513

4. as adds it back later:
   https://github.com/pret/pokeemerald/blob/ef4d99c87e898f34be793fe72bef8f3f3cf2fcb2/sound/MPlayDef.s#L132

To conclude:

• PAN/BEND: ROM value -> -64 by VGMusicStudio -> +64 by VGMusicStudio -> -64 by mid2agb -> +64 by as -> ROM value
• TUNE: ROM value -> -64 by VGMusicStudio -> +64 by VGMusicStudio -> -64 by mid2agb -> +64 by as -> ROM value - 64

Therefore, both PAN and BEND match, but TUNE doesn't match.

It works for the 5 main series Pokémon games doesn't prove it is correct. It may be unused in this game instead. A similar case:
pret/pokeemerald#1593

Other enhancements to the midi exporter won't be accepted right now since there's no way to toggle the output type (matching or enhanced) with a dialog

They have been removed.

[Kermalis]

Hey, I was just making sure it still matches, thanks for the proof. I just didn't remember if the 5 Pokémon games used TUNE or not.

If you make a PR for this commit I'll accept it right away. Your other PR I haven't looked at yet, since I've been so busy irl, but thankfully someone else is helping review it

[Kermalis]

Closed in #100