Fully local speech-to-text (STT) and text-to-speech (TTS) on macOS. No API keys, no network, no cloud. All processing happens on-device.

Requirements

• macOS (Apple Silicon recommended, Intel works too)
• yap CLI in PATH — install via brew install finnvoor/tools/yap
• ffmpeg in PATH (optional, needed for ogg/opus output) — brew install ffmpeg
• say and osascript are macOS built-in

Speech-to-Text (STT)

Transcribe an audio file to text using Apple's on-device speech recognition.

node {baseDir}/scripts/stt.mjs  [locale]

• audio_file: path to audio (ogg, m4a, mp3, wav, etc.)
• locale: optional, e.g. zh_CN, en_US, ja_JP. If omitted, uses system default.
• Outputs transcribed text to stdout.

Supported STT locales

Use node {baseDir}/scripts/stt.mjs --locales to list all supported locales.

Key locales: en_US, en_GB, zh_CN, zh_TW, zh_HK, ja_JP, ko_KR, fr_FR, de_DE, es_ES, pt_BR, ru_RU, vi_VN, th_TH.

Language detection tips

• If the user's recent messages are in Chinese → use zh_CN
• If in English → use en_US
• If mixed or unclear → try without locale (system default)

Text-to-Speech (TTS)

Convert text to an audio file using macOS native TTS.

node {baseDir}/scripts/tts.mjs "" [voice_name] [output_path]

• text: the text to speak
• voice_name: optional, e.g. Yue (Premium), Tingting, Ava (Premium). If omitted, auto-selects the best available voice based on text language.
• output_path: optional, defaults to a timestamped file in ~/.openclaw/media/outbound/
• Outputs the generated audio file path to stdout.
• If ffmpeg is available, output is ogg/opus (ideal for messaging platforms). Otherwise aiff.

Sending as voice note

After generating the audio file, send it using the message tool:

message action=send media= asVoice=true

Voice Management

List available voices, check readiness, or find the best voice for a language:

node {baseDir}/scripts/voices.mjs list [locale]     # List voices, optionally filter by locale
node {baseDir}/scripts/voices.mjs check ""     # Check if a specific voice is downloaded and ready
node {baseDir}/scripts/voices.mjs best        # Get the highest quality voice for a locale

Quality levels

• 1 = compact (low quality, always available)
• 2 = enhanced (mid quality, may need download)
• 3 = premium (highest quality, needs download from System Settings)

If a voice is not available

Tell the user: "Voice X is not downloaded. Go to System Settings → Accessibility → Spoken Content → System Voice → Manage Voices to download it."

Notes

• The say command silently falls back to a default voice if the requested voice is not available (exit code 0, no error). Always use voices.mjs check before calling tts.mjs with a specific voice name.
• Premium voices (e.g. Yue (Premium), Ava (Premium)) sound significantly better but must be manually downloaded by the user.
• Siri voices are not accessible via the speech synthesis API.