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How to add a function that allows players to adjust the speed of music

MapleFall537

  • Poké Ball
    • 5
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    1
    Years
    • Seen Jun 30, 2025
    If your simulator implements acceleration, the music will also be accelerated, so I hope there is a feature that allows players to adjust the playback speed of music so that they can hear normal music while accelerating
     
    This would not be easy, but it is possible. It won't be a quick process.
    1. You would need to add a music speed variable to the SaveBlock2 struct. Two bits will probably suffice, giving you 4 different options.
    2. You would need to add code in src/option_menu.c to display this new option in the Options menu, as well as code to change the value of your music speed variable when the player interacts with this new option.
    3. The ugly part is actually having all of this affect the tempo of the music. You could change how the tempo command is translated from the midi to the .s file, making it always multiply/divide the tempo by whatever value the player has selected. You would need to create an extended command in src/m4a.c and add it to gXcmdTable in the file src\m4a_tables.c to handle all of that, as well as edit tools/mid2agb/agb.cpp so that the midi tempo command doesn't create a TEMPO command in the .s file, but instead creates your extended command. I've written a fairly detailed tutorial on working with music at this low level in pokeemerald (here it is), which should help a lot. What you'll mainly be looking for is under "How to Work with .mid Files", more specifically "Adding Your Own Commands to mid2agb (A Slightly Deeper Look at the .mid → .s Process)". It will take a fair amount of reading to be able to figure out how to make your function, as well as have it show up in the .s files.
     
    WiserVisor said:
    This would not be easy, but it is possible. It won't be a quick process.
    1. You would need to add a music speed variable to the SaveBlock2 struct. Two bits will probably suffice, giving you 4 different options.
    2. You would need to add code in src/option_menu.c to display this new option in the Options menu, as well as code to change the value of your music speed variable when the player interacts with this new option.
    3. The ugly part is actually having all of this affect the tempo of the music. You could change how the tempo command is translated from the midi to the .s file, making it always multiply/divide the tempo by whatever value the player has selected. You would need to create an extended command in src/m4a.c and add it to gXcmdTable in the file src\m4a_tables.c to handle all of that, as well as edit tools/mid2agb/agb.cpp so that the midi tempo command doesn't create a TEMPO command in the .s file, but instead creates your extended command. I've written a fairly detailed tutorial on working with music at this low level in pokeemerald (here it is), which should help a lot. What you'll mainly be looking for is under "How to Work with .mid Files", more specifically "Adding Your Own Commands to mid2agb (A Slightly Deeper Look at the .mid → .s Process)". It will take a fair amount of reading to be able to figure out how to make your function, as well as have it show up in the .s files.
    Click to expand...
    Thank you!!!
     
    WiserVisor said:
    This would not be easy, but it is possible. It won't be a quick process.
    1. You would need to add a music speed variable to the SaveBlock2 struct. Two bits will probably suffice, giving you 4 different options.
    2. You would need to add code in src/option_menu.c to display this new option in the Options menu, as well as code to change the value of your music speed variable when the player interacts with this new option.
    3. The ugly part is actually having all of this affect the tempo of the music. You could change how the tempo command is translated from the midi to the .s file, making it always multiply/divide the tempo by whatever value the player has selected. You would need to create an extended command in src/m4a.c and add it to gXcmdTable in the file src\m4a_tables.c to handle all of that, as well as edit tools/mid2agb/agb.cpp so that the midi tempo command doesn't create a TEMPO command in the .s file, but instead creates your extended command. I've written a fairly detailed tutorial on working with music at this low level in pokeemerald (here it is), which should help a lot. What you'll mainly be looking for is under "How to Work with .mid Files", more specifically "Adding Your Own Commands to mid2agb (A Slightly Deeper Look at the .mid → .s Process)". It will take a fair amount of reading to be able to figure out how to make your function, as well as have it show up in the .s files.
    Click to expand...
    ply_tempo can be found in m4a_1.s. Can I achieve the effect I need by modifying it? If so, what is the appropriate modification?
     
    MapleFall537 said:
    ply_tempo can be found in m4a_1.s. Can I achieve the effect I need by modifying it? If so, what is the appropriate modification?
    Click to expand...
    Theoretically, you could. Unfortunately, that file's written in assembly, which is a bit above my paygrade. I know you would need to create another constant in constants\m4a_constants.inc to be able to access your music speed variable within ply_tempo. Beyond that, I've got nothing. I don't know how you would link this new constant with whatever value the player chooses, nor would I know how to go about impacting the tempo with this constant. I'm sure there are several people who are more well-versed in the assembly-level stuff of the sound engine than me. I think CyanSMP64 is decently knowledgeable. He did a big expansion to the sound engine for it to handle DS Pokémon voices and songs pretty well.
     
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