# OpenMOSS-Team/MOSS-TTS — vLLM serving recipe

> Flagship 8B model of the OpenMOSS MOSS-TTS Family — high-fidelity zero-shot voice cloning, ultra-long stable speech, token-level duration and phoneme control, 20-language code-switched synthesis — served via vLLM-Omni through the OpenAI /v1/audio/speech API (24 kHz mono).

Configuration: hardware `h200` (8× H200) · variant `default` (BF16) · task `t2a`

- Interactive page: https://recipes.vllm.ai/OpenMOSS-Team/MOSS-TTS
- This configuration as JSON: https://recipes.vllm.ai/OpenMOSS-Team/MOSS-TTS.json?hardware=h200

The commands below were rendered for exactly this configuration and take precedence over any example in the guide.

## Other configurations

Change the query string (the same parameters as the page URL) and fetch this URL again. Unknown or incompatible values fall back to the recipe default, so check the Configuration line.

- `hardware`: `h100`, `h200`, `b200`, `gb200`, `b300`, `gb300`, `mi300x`, `mi325x`, `mi350x`, `mi355x`
- `variant`: `default`
- `task`: `t2a`

## Install

Requires vLLM >= 0.22.0.

```bash
uv venv
source .venv/bin/activate
uv pip install -U vllm --torch-backend auto
```

Extra dependencies:

- vLLM-Omni provides the TTS serving backend and the `--omni` serve path. See the installation guide for pre-built wheels or building from source.

```bash
uv pip install git+https://github.com/vllm-project/vllm-omni.git
```

## Serve

vLLM-Omni recipe — the generation endpoints and request examples are in the guide below.

```bash
vllm serve OpenMOSS-Team/MOSS-TTS \
  --deploy-config vllm_omni/deploy/moss_tts.yaml \
  --omni
```

## Guide

> Background reference. Commands in it are examples and may target another configuration — use the Serve section above.

### Overview

[MOSS-TTS](https://huggingface.co/OpenMOSS-Team/MOSS-TTS) is the **flagship 8B
model** of OpenMOSS's [MOSS-TTS Family](https://huggingface.co/OpenMOSS-Team/MOSS-TTS),
a production-grade TTS foundation model served through **vLLM-Omni** with the
OpenAI-compatible `/v1/audio/speech` API. It delivers high-fidelity zero-shot
voice cloning, **ultra-long stable speech (up to ~1 hour)**, token-level
duration control, Pinyin/IPA phoneme control, and **20-language** /
code-switched synthesis. Output is **24 kHz mono** via the shared
`OpenMOSS-Team/MOSS-Audio-Tokenizer` codec (~7 GB, auto-downloaded; override
with `MOSS_TTS_CODEC_PATH`).

The MOSS-TTS Family ships five production-ready models, each with its own
recipe: **MOSS-TTS** (this page, flagship TTS), **MOSS-TTS-Realtime**
(low-latency streaming), **MOSS-TTSD** (multi-speaker dialogue),
**MOSS-VoiceGenerator** (zero-shot voice design), and **MOSS-SoundEffect**
(sound-effect synthesis).

MOSS-TTS is released in two architectures: the 8B `MossTTSDelay` (this
checkpoint, production-recommended) and a 1.7B `MossTTSLocal`
(`OpenMOSS-Team/MOSS-TTS-Local-Transformer`) tuned for streaming-oriented
systems. A `MOSS-TTS-v1.5` point release adds 31-language support and steadier
cloning with `[pause Xs]` markers (same serving path; set `language` for best
results).

### Prerequisites

- **Hardware**: a single CUDA GPU. Reference run: 1x H100 80 GB — ~18 GB for
  the 8B talker + ~8 GB for the codec decoder on the same device
  (`gpu_memory_utilization: 0.85` in `moss_tts.yaml`).
- **vLLM-Omni** targeting vLLM >= 0.22.

### Installation

```bash
uv venv && source .venv/bin/activate
uv pip install git+https://github.com/vllm-project/vllm-omni.git
```

### Launch the server

All MossTTSDelay checkpoints (MOSS-TTS, MOSS-TTSD, MOSS-SoundEffect,
MOSS-VoiceGenerator) share `model_type=moss_tts_delay`, so the deploy config
must be passed explicitly to select the right pipeline:

```bash
vllm serve OpenMOSS-Team/MOSS-TTS --omni \
  --deploy-config vllm_omni/deploy/moss_tts.yaml --port 8000
```

### Client usage

#### Voice cloning (curl)

```bash
curl -X POST http://localhost:8000/v1/audio/speech \
  -H "Content-Type: application/json" \
  -d '{
    "model": "OpenMOSS-Team/MOSS-TTS",
    "input": "Hello, this is a voice cloning test.",
    "voice": "default",
    "ref_audio": "https://raw.githubusercontent.com/OpenMOSS/MOSS-TTS/main/assets/audio/zh_1.wav",
    "response_format": "wav"
  }' --output output.wav
```

### Known limitations

- Output is **24 kHz mono**.
- `MOSS_TTS_CODEC_PATH` overrides the codec checkpoint location if you have a
  local copy.

### References

- [MOSS-TTS model card](https://huggingface.co/OpenMOSS-Team/MOSS-TTS)
- [MOSS-TTS Family](https://huggingface.co/OpenMOSS-Team/MOSS-TTS) · [GitHub](https://github.com/OpenMOSS/MOSS-TTS)
- [vLLM-Omni MOSS-TTS offline example](https://github.com/vllm-project/vllm-omni/tree/main/examples/offline_inference/text_to_speech/moss_tts)