Hardware vibrato — one voice's output modulates another's pitch.
Port of krom (Peter Lemon)'s PitchMod demo (PeterLemon/SNES, SPC700/PitchMod). The S-DSP's PMON feature multiplies a voice's pitch by the OUTPUT of the previous voice. Voice 1 holds a cello note at C5; voice 0 plays a tiny looping square wave at pitch $0003 — inaudibly slow, it is a hardware LFO. One second in, the LFO keys on and the cello starts to sing with vibrato: no CPU, no tables, the DSP does the modulation every sample.
ROM mode: LoROM (project default).
- SNES Concepts
- Pitch modulation (PMON): voice N-1's output scales voice N's pitch
- A silent voice as a hardware LFO (GAIN = depth, PITCH = rate)
- Long FIR echo (EDL 15) as a concert hall
- The apu module upload path (apuWaitBoot/apuUpload/apuExecute)
- What to Observe
- The cello enters dry; after ~1 s the vibrato blooms. The note rings out like a bow stroke (the sample's own ADSR: instant attack, gentle ~7 s fade) and is re-bowed every 7 s, forever. Validation oracle: luna –audio-out.
- Modules Used
- console, apu
- See also
- https://github.com/PeterLemon/SNES — original demo
-
player.spc700.asm — voices, PMON routing, echo
1.16.1