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0671201c05
Add Google's Gemini speech-generation API as 8th TTS backend. Returns base64-encoded signed 16-bit PCM at 24 kHz mono, wrapped in WAV natively via stdlib wave module. Optional ffmpeg conversion to mp3/ogg for Telegram voice bubbles. Supports GEMINI_API_KEY and GOOGLE_API_KEY (fallback), 30 prebuilt voices, configurable model (flash/pro). Cherry-picked from #10922 by @zhonghui5207. Fixes #10918.
156 lines
6.7 KiB
Markdown
156 lines
6.7 KiB
Markdown
---
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sidebar_position: 9
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title: "Voice & TTS"
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description: "Text-to-speech and voice message transcription across all platforms"
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---
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# Voice & TTS
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Hermes Agent supports both text-to-speech output and voice message transcription across all messaging platforms.
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## Text-to-Speech
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Convert text to speech with seven providers:
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| Provider | Quality | Cost | API Key |
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|----------|---------|------|---------|
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| **Edge TTS** (default) | Good | Free | None needed |
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| **ElevenLabs** | Excellent | Paid | `ELEVENLABS_API_KEY` |
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| **OpenAI TTS** | Good | Paid | `VOICE_TOOLS_OPENAI_KEY` |
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| **MiniMax TTS** | Excellent | Paid | `MINIMAX_API_KEY` |
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| **Mistral (Voxtral TTS)** | Excellent | Paid | `MISTRAL_API_KEY` |
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| **NeuTTS** | Good | Free | None needed |
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| **Gemini TTS** | Excellent | Paid (free tier) | `GEMINI_API_KEY` |
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### Platform Delivery
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| Platform | Delivery | Format |
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|----------|----------|--------|
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| Telegram | Voice bubble (plays inline) | Opus `.ogg` |
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| Discord | Voice bubble (Opus/OGG), falls back to file attachment | Opus/MP3 |
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| WhatsApp | Audio file attachment | MP3 |
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| CLI | Saved to `~/.hermes/audio_cache/` | MP3 |
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### Configuration
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```yaml
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# In ~/.hermes/config.yaml
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tts:
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provider: "edge" # "edge" | "elevenlabs" | "openai" | "minimax" | "mistral" | "neutts"
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speed: 1.0 # Global speed multiplier (provider-specific settings override this)
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edge:
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voice: "en-US-AriaNeural" # 322 voices, 74 languages
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speed: 1.0 # Converted to rate percentage (+/-%)
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elevenlabs:
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voice_id: "pNInz6obpgDQGcFmaJgB" # Adam
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model_id: "eleven_multilingual_v2"
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openai:
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model: "gpt-4o-mini-tts"
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voice: "alloy" # alloy, echo, fable, onyx, nova, shimmer
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base_url: "https://api.openai.com/v1" # Override for OpenAI-compatible TTS endpoints
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speed: 1.0 # 0.25 - 4.0
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minimax:
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model: "speech-2.8-hd" # speech-2.8-hd (default), speech-2.8-turbo
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voice_id: "English_Graceful_Lady" # See https://platform.minimax.io/faq/system-voice-id
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speed: 1 # 0.5 - 2.0
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vol: 1 # 0 - 10
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pitch: 0 # -12 - 12
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mistral:
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model: "voxtral-mini-tts-2603"
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voice_id: "c69964a6-ab8b-4f8a-9465-ec0925096ec8" # Paul - Neutral (default)
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neutts:
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ref_audio: ''
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ref_text: ''
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model: neuphonic/neutts-air-q4-gguf
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device: cpu
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gemini:
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model: "gemini-2.5-flash-preview-tts" # or gemini-2.5-pro-preview-tts
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voice: "Kore" # 30 prebuilt voices (Zephyr, Puck, Charon, ...)
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```
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**Speed control**: The global `tts.speed` value applies to all providers by default. Each provider can override it with its own `speed` setting (e.g., `tts.openai.speed: 1.5`). Provider-specific speed takes precedence over the global value. Default is `1.0` (normal speed).
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### Telegram Voice Bubbles & ffmpeg
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Telegram voice bubbles require Opus/OGG audio format:
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- **OpenAI, ElevenLabs, and Mistral** produce Opus natively — no extra setup
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- **Edge TTS** (default) outputs MP3 and needs **ffmpeg** to convert:
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- **MiniMax TTS** outputs MP3 and needs **ffmpeg** to convert for Telegram voice bubbles
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- **NeuTTS** outputs WAV and also needs **ffmpeg** to convert for Telegram voice bubbles
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- **Gemini TTS** returns raw PCM (wrapped in WAV natively) and needs **ffmpeg** to convert for Telegram voice bubbles
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```bash
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# Ubuntu/Debian
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sudo apt install ffmpeg
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# macOS
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brew install ffmpeg
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# Fedora
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sudo dnf install ffmpeg
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```
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Without ffmpeg, Edge TTS, MiniMax TTS, and NeuTTS audio are sent as regular audio files (playable, but shown as a rectangular player instead of a voice bubble).
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:::tip
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If you want voice bubbles without installing ffmpeg, switch to the OpenAI, ElevenLabs, or Mistral provider.
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:::
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## Voice Message Transcription (STT)
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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.
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| Provider | Quality | Cost | API Key |
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|----------|---------|------|---------|
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| **Local Whisper** (default) | Good | Free | None needed |
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| **Groq Whisper API** | Good–Best | Free tier | `GROQ_API_KEY` |
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| **OpenAI Whisper API** | Good–Best | Paid | `VOICE_TOOLS_OPENAI_KEY` or `OPENAI_API_KEY` |
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:::info Zero Config
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Local transcription works out of the box when `faster-whisper` is installed. If that's unavailable, Hermes can also use a local `whisper` CLI from common install locations (like `/opt/homebrew/bin`) or a custom command via `HERMES_LOCAL_STT_COMMAND`.
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:::
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### Configuration
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```yaml
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# In ~/.hermes/config.yaml
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stt:
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provider: "local" # "local" | "groq" | "openai" | "mistral"
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local:
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model: "base" # tiny, base, small, medium, large-v3
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openai:
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model: "whisper-1" # whisper-1, gpt-4o-mini-transcribe, gpt-4o-transcribe
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mistral:
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model: "voxtral-mini-latest" # voxtral-mini-latest, voxtral-mini-2602
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```
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### Provider Details
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**Local (faster-whisper)** — Runs Whisper locally via [faster-whisper](https://github.com/SYSTRAN/faster-whisper). Uses CPU by default, GPU if available. Model sizes:
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| Model | Size | Speed | Quality |
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|-------|------|-------|---------|
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| `tiny` | ~75 MB | Fastest | Basic |
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| `base` | ~150 MB | Fast | Good (default) |
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| `small` | ~500 MB | Medium | Better |
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| `medium` | ~1.5 GB | Slower | Great |
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| `large-v3` | ~3 GB | Slowest | Best |
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**Groq API** — Requires `GROQ_API_KEY`. Good cloud fallback when you want a free hosted STT option.
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**OpenAI API** — Accepts `VOICE_TOOLS_OPENAI_KEY` first and falls back to `OPENAI_API_KEY`. Supports `whisper-1`, `gpt-4o-mini-transcribe`, and `gpt-4o-transcribe`.
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**Mistral API (Voxtral Transcribe)** — Requires `MISTRAL_API_KEY`. Uses Mistral's [Voxtral Transcribe](https://docs.mistral.ai/capabilities/audio/speech_to_text/) models. Supports 13 languages, speaker diarization, and word-level timestamps. Install with `pip install hermes-agent[mistral]`.
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**Custom local CLI fallback** — Set `HERMES_LOCAL_STT_COMMAND` if you want Hermes to call a local transcription command directly. The command template supports `{input_path}`, `{output_dir}`, `{language}`, and `{model}` placeholders.
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### Fallback Behavior
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If your configured provider isn't available, Hermes automatically falls back:
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- **Local faster-whisper unavailable** → Tries a local `whisper` CLI or `HERMES_LOCAL_STT_COMMAND` before cloud providers
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- **Groq key not set** → Falls back to local transcription, then OpenAI
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- **OpenAI key not set** → Falls back to local transcription, then Groq
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- **Mistral key/SDK not set** → Skipped in auto-detect; falls through to next available provider
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- **Nothing available** → Voice messages pass through with an accurate note to the user
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