SNESMOD Sound Effects

‍Sound effect playback with pitch control. Five instrument samples on the buttons, three pitch settings on the D-pad. No background music – effects only.

Build & Run

cd $OPENSNES_HOME
make -C examples/audio/snesmod_sfx

Then open sfx.sfc in your emulator (Mesen2 recommended).

Controls

Button	Action
A	Play "Tada"
B	Play "Hall Strings"
X	Play "Honky Tonk Piano"
Y	Play "Marimba"
L / R	Play "Cowbell"
D-Pad Left / Right	Cycle pitch (Low / Normal / High)

What You'll Learn

• How to initialize SNESMOD for effects-only playback (no music)
• Loading individual sound effects from a soundbank with snesmodLoadEffect()
• Playing effects with volume, pan, and pitch via snesmodPlayEffect()
• Using three built-in pitch constants: SNESMOD_PITCH_LOW, SNESMOD_PITCH_NORMAL, SNESMOD_PITCH_HIGH
• Why snesmodProcess() must be called every frame, even without music

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SNES Concepts

SNESMOD Initialization

SNESMOD is initialized in two steps: snesmodInit() sets up the SPC700 driver, then snesmodSetSoundbank() tells it which ROM bank contains the soundbank data:

snesmodInit();
snesmodSetSoundbank(SOUNDBANK_BANK);

SOUNDBANK_BANK is a constant generated by the build system from the soundbank source files listed in the Makefile's SOUNDBANK_SRC variable.

Loading and Playing Effects

Each effect must be loaded before it can be played. This transfers the BRR sample data to the SPC700's 64KB audio RAM:

for (i = 0; i < NUM_EFFECTS; i++) {
    snesmodLoadEffect(i);
}

To play an effect, call snesmodPlayEffect() with four parameters – the effect ID, volume (0-127), pan (0=left, 128=center, 255=right), and pitch:

snesmodPlayEffect(SFX_TADA, 127, 128, pitch);

The Soundbank

The soundbank is built from an Impulse Tracker .it file (sfx/effectssfx.it) that contains five instrument samples. The smconv tool converts it into a binary soundbank at build time. The .it file holds the raw instrument definitions but no music patterns – this is an effects-only soundbank.

Index	Effect	Constant
0	Tada	SFX_TADA
1	Hall Strings	SFX_HALL_STRINGS
2	Honky Tonk Piano	SFX_HONKY_TONK_PIANO
3	Marimba	SFX_MARIMBA_1
4	Cowbell	SFX_COWBELL

Text Display

The on-screen HUD uses the text library module (textInit, textLoadFont, textPrintAt, textFlush) for rendering control labels and the current pitch setting. textFlush() is called after updating the pitch display to transfer the text buffer to VRAM.

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Files

File	Purpose
main.c	SFX triggering, pitch control, text display
sfx/effectssfx.it	Impulse Tracker file with 5 instrument samples
soundbank.h	Generated header with effect constants and bank info
Makefile	Build configuration (USE_SNESMOD := 1, SOUNDBANK_SRC)

What's Next?

SNESMOD Music: SNESMOD Music - Tracker music playback

Graphics: Simple Sprite - Display a sprite on screen