fish.audio TTS

Requires FISH_AUDIO_API_KEY in .env (create one at https://fish.audio/go-api/api-keys/). Create voice models in the fish.audio playground and pass their id as reference_id to reuse a cloned voice.

Current API

Single synchronous call returning raw audio bytes:

POST https://api.fish.audio/v1/tts
Authorization: Bearer ${FISH_AUDIO_API_KEY}
Content-Type: application/json
model: <backend model>     # HTTP header selects the backend, e.g. s1

The backend model is chosen with the model HTTP header, not a body field. In OpenMontage this maps to the tool's model input.

Backend models

model is required — there is no default. Pass one of:

• s2.1-pro — latest generation. Best quality: inline emotion tags, 80+ languages, multi-speaker. Hero narration.
• s2.1-pro-free — promotional free access to s2.1-pro. Drafts, samples, and validation runs at $0 during the promo window only. Per the fish.audio announcement: free through August 31, 2026, subject to Fair Use, no SLA/latency guarantee, requests may be retained, and commercial use is restricted. Never route production or client narration through it.
• s2-pro — first S2 generation. Stable high quality with emotion-tag support.
• s1 — previous flagship. Kept for compatibility with existing integrations.

Billing is per UTF-8 byte of input text (not per character). CJK text and emoji cost 3-4x an ASCII character of the same visible length. Current list pricing: s1 / s2-pro / s2.1-pro = $15 per 1M bytes, s2.1-pro-free = $0 during the promo window only (the tool's estimate_cost() switches to the paid s2.1-pro rate after August 31, 2026). Verify current pricing at https://docs.fish.audio/developer-guide/models-pricing/pricing-and-rate-limits before large batches.

Inline emotion tags (S2 models only)

s2-pro / s2.1-pro / s2.1-pro-free interpret inline emotion tags embedded in the text:

• Tags like [laugh], [whispers] change the delivery mid-sentence.
• Example: "That's hilarious [laugh] but let me explain seriously."
• s1 does not interpret emotion tags — they may be read out as plain text, so strip them when targeting s1.

Voice selection (reference_id)

• Build or pick a voice in the fish.audio playground, then copy its model id.
• Pass it as reference_id. The selector's generic voice_id is accepted as an alias when reference_id is absent.
• Without a reference_id, fish.audio uses its default voice for the chosen model.

Inline on-the-fly cloning (uploading reference audio + text per request) is not supported by this tool — create a voice model in the playground first.

OpenMontage Usage

Generate with the TTS selector:

from tools.audio.tts_selector import TTSSelector

result = TTSSelector().execute({
    "preferred_provider": "fish_audio",
    "text": "Here's why compound interest quietly beats every get-rich-quick scheme.",
    "model": "s1",
    "reference_id": "<playground voice model id>",
    "output_path": "projects/my-video/assets/audio/narration.mp3",
})

Or call the provider directly:

from tools.audio.fish_audio_tts import FishAudioTTS

result = FishAudioTTS().execute({
    "text": "Short sample line for approval.",
    "model": "s1",
    "reference_id": "<playground voice model id>",
    "output_path": "projects/my-video/assets/audio/fish_sample.mp3",
})

The provider writes the audio to output_path and returns data.output plus the resolved model and reference_id.

Quality & latency tuning

• latency: normal (default, best quality), balanced (a little faster), or low (fastest, slight quality cost).
• normalize: default true; keep it on so numbers, dates, and currency read naturally.
• prosody: optional { "speed": 1.0, "volume": 0 } to nudge pace/loudness.
• mp3_bitrate: 128 is a good default; raise to 192 for music-bed-heavy mixes.
• temperature: default 0.7. Raise toward 0.9 for more expressive reads (recommended when leaning on emotion tags); lower for a steadier, more predictable delivery.
• top_p / repetition_penalty: usually leave at the defaults (0.7 / 1.2).

Recommended Workflow

1. Generate a 10-15 second sample with the chosen model + reference_id before a full paid narration.
2. Ask the user to approve voice naturalness, emotion, and pace.
3. Generate the full narration only after approval.
4. For batch/localization variants where cost matters, prototype on s2.1-pro-free (promo-window $0; non-commercial drafts only) and upgrade the final to s2.1-pro.

Troubleshooting

• 401 Unauthorized: wrong or missing FISH_AUDIO_API_KEY.
• 402 / payment errors: account credit exhausted.
• 404 / bad voice: the reference_id is wrong or not owned by this account.
• Empty/short audio: check that text is non-empty and normalize is not stripping the whole input.

Safety

Never print or write the API key to logs, metadata, patches, or project artifacts. .env.example should contain only empty variable names.