vllm-omni/recipes/IndexTeam/IndexTTS-2.md

IndexTTS-2 for voice-cloned TTS on 1x GPU

Summary

• Vendor: IndexTeam
• Model: IndexTeam/IndexTTS-2
• Task: Text-to-speech with voice cloning and optional emotion control
• Mode: Online serving with the OpenAI-compatible /v1/audio/speech API
• Maintainer: Community

When to use this recipe

Use this recipe to serve IndexTTS-2 as a two-stage TTS system for voice-cloned speech synthesis. Each request provides synthesis text plus either a reference audio clip or an uploaded audio voice; the model returns 22.05 kHz mono speech. IndexTTS-2 also supports optional emotion conditioning through model-specific extra_params.

IndexTTS-2 is not an async-chunk streaming model in the bundled deployment configuration: the S2Mel flow-matching stage consumes the full mel-code sequence from the AR talker before it produces audio. The OpenAI-compatible endpoint can still be called with stream=true as an HTTP compatibility path, but that should not be interpreted as incremental model streaming.

References

• Upstream model: IndexTeam/IndexTTS-2 on Hugging Face
• Online serving example: examples/online_serving/text_to_speech/README.md#indextts-2
• Offline inference example: examples/offline_inference/text_to_speech/README.md#indextts-2
• OpenAI-compatible client: examples/online_serving/text_to_speech/indextts2/speech_client.py
• Deploy config: vllm_omni/deploy/indextts2.yaml

Hardware Support

GPU

1x L4 24GB or larger CUDA GPU

Environment

• OS: Linux
• Python: 3.10+
• Driver / runtime: NVIDIA CUDA environment
• vLLM version: Match the repository requirements for your checkout
• vLLM-Omni version or commit: Use the commit you are deploying from

Command

Start the server from the repository root:

vllm serve IndexTeam/IndexTTS-2 --omni --trust-remote-code --port 8092

The bundled deployment config is selected automatically for the indextts2 model type. To make the config choice explicit, pass it directly:

vllm serve IndexTeam/IndexTTS-2 --omni --trust-remote-code --port 8092 \
  --deploy-config vllm_omni/deploy/indextts2.yaml

Verification

Run the bundled client. Local audio paths passed to this client are converted to base64 data URLs before they are sent to the HTTP API:

python examples/online_serving/text_to_speech/indextts2/speech_client.py \
  --api-base http://localhost:8092 \
  --text "你好，这是 IndexTTS-2 语音合成测试。" \
  --ref-audio /path/to/reference.wav \
  --output indextts2.wav

For a raw HTTP request, pass ref_audio as an HTTP(S) URL, a base64 data URL, or a file:// URI allowed by the server's --allowed-local-media-path. Do not pass an arbitrary local filesystem path directly in JSON unless your client converts it first:

curl http://localhost:8092/v1/audio/speech \
  -H "Content-Type: application/json" \
  -d '{
    "model": "IndexTeam/IndexTTS-2",
    "input": "你好，这是 IndexTTS-2 语音合成测试。",
    "response_format": "wav",
    "ref_audio": "data:audio/wav;base64,<BASE64_ENCODED_AUDIO>"
  }' \
  --output indextts2.wav

Optional emotion conditioning is passed through extra_params. Use one emotion source mode at a time:

curl http://localhost:8092/v1/audio/speech \
  -H "Content-Type: application/json" \
  -d '{
    "model": "IndexTeam/IndexTTS-2",
    "input": "今天心情很好！",
    "response_format": "wav",
    "ref_audio": "data:audio/wav;base64,<BASE64_ENCODED_REFERENCE_AUDIO>",
    "extra_params": {
      "emo_vector": [1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0],
      "emo_alpha": 0.8
    }
  }' \
  --output indextts2_happy.wav

Notes

• Hardware scope: the default config is a single-GPU CUDA deployment. Stage 0 and Stage 1 share GPU 0 by default.
• Audio output: 22.05 kHz mono WAV.
• Voice cloning: ref_audio is required for the documented raw request path. Alternatively, pass voice only when it names an uploaded audio voice from /v1/audio/voices; IndexTTS-2 does not provide a built-in text-only preset voice in this serving recipe.
• Reference audio format: use an HTTP(S) URL, a base64 data URL, or a file:// URI allowed by the server's --allowed-local-media-path for raw API calls. The bundled Python client accepts local paths and converts them to base64 data URLs.
• Emotion control: extra_params.emo_audio, extra_params.emo_vector, and extra_params.use_emo_text are alternative conditioning modes. Official precedence is use_emo_text > emo_vector > emo_audio > same emotion as the speaker reference. The emo_vector order is [happy, angry, sad, afraid, disgusted, melancholic, surprised, calm].
• Streaming limitation: async_chunk is disabled in vllm_omni/deploy/indextts2.yaml; S2Mel requires the full mel-code sequence before audio generation.
• First request can be slower because reference encoders and auxiliary models are lazily loaded and cached.