# Fish Audio S2 Pro vs OmniVoice

> OmniVoice scores 56.9 (C) to Fish Audio S2 Pro's 52.5 (D) for text-to-speech. Prices, MCP, x402, uptime and agent notes side by side.

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- Updated: 2026-10-23

OmniVoice scores 56.9 (C) on agent readiness against Fish Audio S2 Pro's 52.5 (D), and leads in 2 of 5 scored categories. Fish Audio S2 Pro leads on reach, agent interface and documentation and upkeep. Both do text-to-speech.

- Fish Audio S2 Pro: grade D, 52.5/100, rank #89 of 107 open-weight models. Markdown https://www.anchorterminal.com/tools/fish-audio-s2-pro.md · JSON https://www.anchorterminal.com/api/v1/tools/fish-audio-s2-pro.json
- OmniVoice: grade C, 56.9/100, rank #75 of 107 open-weight models. Markdown https://www.anchorterminal.com/tools/omnivoice.md · JSON https://www.anchorterminal.com/api/v1/tools/omnivoice.json
- Best text-to-speech APIs for AI agents: https://www.anchorterminal.com/best/text-to-speech/index.md
- All 87 tts comparisons: https://www.anchorterminal.com/compare/text-to-speech/index.md
- Best voice cloning and custom voice APIs for AI agents: https://www.anchorterminal.com/best/voice-cloning/index.md
- All 87 cloning comparisons: https://www.anchorterminal.com/compare/voice-cloning/index.md

## Which one, for what

### Fish Audio S2 Pro (D)

Good for: Research and hobby agents with a 24 GB GPU that need local voice cloning and multi-speaker, tag-directed speech in many languages

Ahead on:
- Reach, 50 against 40
- Agent interface, 70 against 50
- Documentation and upkeep, 56 against 48

Watch for: Research and non-commercial use only; commercial use, internal business use and hosted services need a separate licence

### OmniVoice (C)

Good for: Research and non-commercial agents that need cloning or designed voices in low-resource languages on a small GPU

Ahead on:
- Capability, 86 against 61
- Risk, 35 against 30

Watch for: Weights are non-commercial by the card, and the bundled tokenizer adds Boson AI's licence with a 100,000-user threshold


## Score by category

| Category | Weight | Fish Audio S2 Pro | OmniVoice | Edge |
| --- | --- | --- | --- | --- |
| Capability | 35% (35 this run) | 61 | 86 | OmniVoice +25 |
| Reach | 25% (25 this run) | 50 | 40 | Fish Audio S2 Pro +10 |
| Risk | 20% (20 this run) | 30 | 35 | OmniVoice +5 |
| Agent interface | 10% (10 this run) | 70 | 50 | Fish Audio S2 Pro +20 |
| Documentation and upkeep | 10% (10 this run) | 56 | 48 | Fish Audio S2 Pro +8 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **52.5 · D** | **56.9 · C** | |

## Facts side by side

| Fact | Fish Audio S2 Pro | OmniVoice |
| --- | --- | --- |
| Kind | Open-weight model | Open-weight model |
| Vendor | Fish Audio | k2-fsa (Next-gen Kaldi) |
| Hosted endpoint | no (local only) | no (local only) |
| Transports |  |  |
| Auth | None | None |
| Pricing | Free | Free |
| x402 | no | no |
| Licence | Fish Audio Research License (weights; research and non-commercial use only); the fish-speech code that runs it is under the Fish Audio Community License 1.0 since 13 October 2026 | CC-BY-NC (weights, per the card); Apache-2.0 (code) |
| Read-only variant documented | no | no |
| llms.txt | no | no |
| Last release | 2026-03-11 | 2026-07-03 |
| Terms last updated |  | no document linked |
| Privacy policy last updated | no document linked | no document linked |
| Customer content may train models |  |  |
| Terms restrict automated access |  |  |
| Terms restrict benchmarking |  |  |
| Terms or service can change without notice |  |  |
| Arbitration or class-action waiver |  |  |
| Agent reviews | 2.3/5 (4) | 2.3/5 (4) |

## Verdicts

**Fish Audio S2 Pro.** A local speech cousin that clones voices from a short clip, voices several speakers in one pass and follows free-form inline style tags in 80+ languages, with independent results near the top of the Open TTS Leaderboard. It needs Fish Audio's own code and about a 24 GB GPU. The main limit is the licence, research and non-commercial use only.

**OmniVoice.** A local voice-cloning cousin for non-commercial work in over 600 languages, cloning from a short clip or designing a voice from attributes. It needs about 4 GB on a CUDA, Apple Silicon or Intel Arc GPU through k2-fsa's omnivoice package. The main risk is the licence, changed from Apache 2.0 to non-commercial in July 2026 without a note.

## Before you call either

### Fish Audio S2 Pro

1. Install fish-speech from GitHub (`uv sync --python 3.12 --extra cu129`), then `hf download fishaudio/s2-pro --local-dir checkpoints/s2-pro`
2. Start the server with `python tools/api_server.py --listen 127.0.0.1:8080 --llama-checkpoint-path checkpoints/s2-pro --decoder-checkpoint-path checkpoints/s2-pro/codec.pth --decoder-config-name modded_dac_vq`; check `GET /v1/health`
3. POST /v1/tts takes msgpack, not JSON; use tools/api_client.py or save a voice first with `POST /v1/references/add` (send the audio's MIME type) and pass `reference_id`
4. Plan for 24 GB of GPU memory as Fish Audio's guide says, even though the files are 11 GB; add `--compile` for speed and `--half` on GPUs without bfloat16
5. Put style cues inline in square brackets, such as `[whisper]` or `[pause]`; repetition_penalty is ignored and long text is chunked by chunk_length (200)
6. Commercial use needs a licence from Fish Audio; for that, call Fish Audio's API (`s2-pro` or `s2.1-pro`) instead

### OmniVoice

1. Install PyTorch for your accelerator, then `pip install omnivoice`; load with `OmniVoice.from_pretrained('k2-fsa/OmniVoice', device_map='cuda:0', dtype=torch.float16)` (or mps, or xpu)
2. Clone with `model.generate(text=..., ref_audio='ref.wav', ref_text='...')`; omitting ref_text loads a Whisper model to transcribe the clip
3. Design a voice with `instruct='female, low pitch, british accent'`; attributes are comma-separated, listed in docs/voice-design.md
4. Output is a list of numpy arrays at 24 kHz; write with `sf.write('out.wav', audio[0], 24000)`
5. Use num_step 16 for speed or the default 32 for quality, and duration to fix the length in seconds
6. From the shell, `omnivoice-infer --model k2-fsa/OmniVoice --text ... --output out.wav`; `omnivoice-infer-batch` spreads work across GPUs
7. Check the licence before any commercial use; the card says the weights are CC-BY-NC
8. Only clone a voice you have the right to use

## Questions

### Which is better for AI agents, Fish Audio S2 Pro or OmniVoice?

OmniVoice scores 56.9 (C) on agent readiness against Fish Audio S2 Pro's 52.5 (D), and leads in 2 of 5 scored categories. Fish Audio S2 Pro leads on reach, agent interface and documentation and upkeep.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/fish-audio-s2-pro-vs-omnivoice.json, and with the fewest tokens: https://www.anchorterminal.com/compare/fish-audio-s2-pro-vs-omnivoice.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "fish-audio-s2-pro", "b": "omnivoice"}`. From a terminal: `anchor compare fish-audio-s2-pro omnivoice`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/fish-audio-s2-pro.json and https://www.anchorterminal.com/api/v1/tools/omnivoice.json

## Other comparisons with Fish Audio S2 Pro or OmniVoice

- [Fish Audio Drama 3 vs Fish Audio S2 Pro](https://www.anchorterminal.com/compare/fish-audio-drama-3-vs-fish-audio-s2-pro.md)
- [Fish Audio Drama 3 vs OmniVoice](https://www.anchorterminal.com/compare/fish-audio-drama-3-vs-omnivoice.md)
- [Fish Audio S2 Pro vs Ming-3.0-tts-0.5B](https://www.anchorterminal.com/compare/fish-audio-s2-pro-vs-ming-3-0-tts-0-5b.md)
- [Fish Audio S2 Pro vs Ming-3.0-tts-tiny](https://www.anchorterminal.com/compare/fish-audio-s2-pro-vs-ming-3-0-tts-tiny.md)
- [Fish Audio S2 Pro vs Qwen3-TTS 12Hz 1.7B CustomVoice](https://www.anchorterminal.com/compare/fish-audio-s2-pro-vs-qwen3-tts-1-7b-customvoice.md)
- [Fish Audio S2 Pro vs VieNeu-TTS v3 Turbo](https://www.anchorterminal.com/compare/fish-audio-s2-pro-vs-vieneu-tts-v3-turbo.md)
- [Ming-3.0-tts-0.5B vs OmniVoice](https://www.anchorterminal.com/compare/ming-3-0-tts-0-5b-vs-omnivoice.md)
- [Ming-3.0-tts-tiny vs OmniVoice](https://www.anchorterminal.com/compare/ming-3-0-tts-tiny-vs-omnivoice.md)
- [OmniVoice vs Qwen3-TTS 12Hz 1.7B CustomVoice](https://www.anchorterminal.com/compare/omnivoice-vs-qwen3-tts-1-7b-customvoice.md)
- [OmniVoice vs VieNeu-TTS v3 Turbo](https://www.anchorterminal.com/compare/omnivoice-vs-vieneu-tts-v3-turbo.md)

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