Files
hermes-agent/website/docs/user-guide/features/tts.md
teknium1 b430b5acfe feat(stt): add free local whisper transcription via faster-whisper
Replace OpenAI-only STT with a dual-provider system mirroring the TTS
architecture (Edge TTS free / ElevenLabs paid):

  STT: faster-whisper local (free, default) / OpenAI Whisper API (paid)

Changes:
- tools/transcription_tools.py: Full rewrite with provider dispatch,
  config loading, local faster-whisper backend, and OpenAI API backend.
  Auto-downloads model (~150MB for 'base') on first voice message.
  Singleton model instance reused across calls.
- pyproject.toml: Add faster-whisper>=1.0.0 as core dependency
- hermes_cli/config.py: Expand stt config to match TTS pattern with
  provider selection and per-provider model settings
- agent/context_compressor.py: Fix .strip() crash when LLM returns
  non-string content (dict from llama.cpp, None). Fixes #1100 partially.
- tests/: 23 new tests for STT providers + 2 for compressor fix
- docs/: Updated Voice & TTS page with STT provider table, model sizes,
  config examples, and fallback behavior

Fallback behavior:
- Local not installed → OpenAI API (if key set)
- OpenAI key not set → local whisper (if installed)
- Neither → graceful error message to user

Co-authored-by: Jah-yee <Jah-yee@users.noreply.github.com>
2026-03-13 09:07:09 -07:00

3.6 KiB
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9 Voice & TTS Text-to-speech and voice message transcription across all platforms

Voice & TTS

Hermes Agent supports both text-to-speech output and voice message transcription across all messaging platforms.

Text-to-Speech

Convert text to speech with three providers:

Provider Quality Cost API Key
Edge TTS (default) Good Free None needed
ElevenLabs Excellent Paid ELEVENLABS_API_KEY
OpenAI TTS Good Paid VOICE_TOOLS_OPENAI_KEY

Platform Delivery

Platform Delivery Format
Telegram Voice bubble (plays inline) Opus .ogg
Discord Audio file attachment MP3
WhatsApp Audio file attachment MP3
CLI Saved to ~/.hermes/audio_cache/ MP3

Configuration

# In ~/.hermes/config.yaml
tts:
  provider: "edge"              # "edge" | "elevenlabs" | "openai"
  edge:
    voice: "en-US-AriaNeural"   # 322 voices, 74 languages
  elevenlabs:
    voice_id: "pNInz6obpgDQGcFmaJgB"  # Adam
    model_id: "eleven_multilingual_v2"
  openai:
    model: "gpt-4o-mini-tts"
    voice: "alloy"              # alloy, echo, fable, onyx, nova, shimmer

Telegram Voice Bubbles & ffmpeg

Telegram voice bubbles require Opus/OGG audio format:

  • OpenAI and ElevenLabs produce Opus natively — no extra setup
  • Edge TTS (default) outputs MP3 and needs ffmpeg to convert:
# Ubuntu/Debian
sudo apt install ffmpeg

# macOS
brew install ffmpeg

# Fedora
sudo dnf install ffmpeg

Without ffmpeg, Edge TTS audio is sent as a regular audio file (playable, but shows as a rectangular player instead of a voice bubble).

:::tip If you want voice bubbles without installing ffmpeg, switch to the OpenAI or ElevenLabs provider. :::

Voice Message Transcription (STT)

Voice messages sent on Telegram, Discord, WhatsApp, Slack, or Signal are automatically transcribed and injected as text into the conversation. The agent sees the transcript as normal text.

Provider Quality Cost API Key
Local Whisper (default) Good Free None needed
OpenAI Whisper API GoodBest Paid VOICE_TOOLS_OPENAI_KEY

:::info Zero Config Local transcription works out of the box — no API key needed. The faster-whisper model (~150 MB for base) is auto-downloaded on first voice message. :::

Configuration

# In ~/.hermes/config.yaml
stt:
  provider: "local"           # "local" (free, faster-whisper) | "openai" (API)
  local:
    model: "base"             # tiny, base, small, medium, large-v3
  openai:
    model: "whisper-1"        # whisper-1, gpt-4o-mini-transcribe, gpt-4o-transcribe

Provider Details

Local (faster-whisper) — Runs Whisper locally via faster-whisper. Uses CPU by default, GPU if available. Model sizes:

Model Size Speed Quality
tiny ~75 MB Fastest Basic
base ~150 MB Fast Good (default)
small ~500 MB Medium Better
medium ~1.5 GB Slower Great
large-v3 ~3 GB Slowest Best

OpenAI API — Requires VOICE_TOOLS_OPENAI_KEY. Supports whisper-1, gpt-4o-mini-transcribe, and gpt-4o-transcribe.

Fallback Behavior

If your configured provider isn't available, Hermes automatically falls back:

  • Local not installed → Falls back to OpenAI API (if key is set)
  • OpenAI key not set → Falls back to local Whisper (if installed)
  • Neither available → Voice messages pass through with a note to the user