stackchan-voice TTS

stackchan-voice is an offline Japanese TTS engine bundled with the device firmware and the WASM simulator. It synthesizes 8 kHz PCM and converts it to the 24 kHz mono output used by Stack-chan. Device firmware streams that PCM to AudioOut. The WASM simulator renders the same vendored engine into a WAV buffer and plays it through the browser Audio bridge. Playback power is forwarded through the standard TTS.onPlayed callback, so the existing runtime mouth animation works without a conversation-module-specific integration.

Select it with these preferences:

{
  "tts": {
    "type": "stackchan-voice",
    "voice": "normal",
    "speed": 100,
    "volume": 0.1
  }
}

voice accepts normal or cute. Both supported targets default to normal and speed 100. CoreS3 uses volume 0.1; the browser simulator uses 0.5.

The firmware repository contains a reproducible snapshot under vendor/stackchan-voice. Refresh it from a local checkout with:

node scripts/vendor-stackchan-voice.mjs \
  --source /path/to/stackchan-voice \
  --revision <git-revision> [--dirty]

The script verifies the dictionary digest from its source metadata and writes SHA-256 hashes for every copied file to VENDOR_SOURCE.json.

The M5StackChan CoreS3 firmware and WASM simulator select stackchan-voice by default. The block editor's 「おしゃべり」 block generates await robot.audio.say(...), so the same block runs this engine on both targets.

Singing

stackchan-voice can pin each mora to an equal-tempered note and an exact duration. The public audio capability accepts the engine's raw koe notation:

await robot.audio.sing(
  '#C4,450ki#C4,450ra#G4,450ki#G4,450ra' +
    '#A4,450hi#A4,450ka#G4,900ru#R,150',
)

#C4,450ki sings the mora ki at C4 for 450 milliseconds. + and - select sharps and flats, and #R,150 inserts a 150 millisecond rest. Notes hold a stable pitch with a short portamento; notes longer than roughly 350 ms also receive a delayed vibrato. One note consumes one mora.

Singing is optional on the active TTS provider. robot.audio.sing(...) returns a failed result instead of silently speaking the notation when the current provider does not implement singing.

The block editor hides the raw notation. Its 「テンポ … で…を歌う」 block takes one score list and one global BPM. Every list item has the same [pitch, beats, lyric] triple shape; a rest uses ['R', beats, '']. The generated helper validates the list, converts beat counts to exact milliseconds, romanizes each one-kana-mora lyric, and calls robot.audio.sing(...). CoreS3 and the browser simulator therefore play the same score without doing text-to-koe conversion inside the voice provider.