[Model] Add IndexTTS2 text-to-speech support (#3838)

Signed-off-by: BeatSeat <wendavid552@gmail.com>
Signed-off-by: David <david@podcast.ai>
Signed-off-by: wendavid552 <wendavid552@gmail.com>
Signed-off-by: WenDavid <davidzhangcf@foxmail.com>

examples/offline_inference/text_to_speech/README.md

@@ -23,6 +23,7 @@ list of supported architectures across all modalities, see
 | OmniVoice | `k2-fsa/OmniVoice` | 2 (gen + dec) | ✓ | — | voice design, language hint | 24 kHz |
 | Qwen3-TTS | `Qwen/Qwen3-TTS-12Hz-1.7B-{CustomVoice,VoiceDesign,Base}` | 2 (talker + code2wav) | ✓ (Base) | ✓ | 3 task variants | 24 kHz |
 | VoxCPM2 | `openbmb/VoxCPM2` | single (native AR) | ✓ | ✓ (online) | continuation | 48 kHz |
+| IndexTTS-2 | `IndexTeam/IndexTTS-2` | 2 (AR talker + S2Mel DiT + BigVGAN) | ✓ (required) | — | emotion control (`--emo-audio`, `--emo-text`, `--emo-vector`) | 22.05 kHz |
 | Voxtral TTS | `mistralai/Voxtral-4B-TTS-2603` | varies | ✓ | ✓ | voice presets | 24 kHz |
 
 ## Common Quick Start
@@ -436,6 +437,50 @@ Streaming is exposed through the online OpenAI Speech API (`stream=true`). See [
 
 ---
 
+## IndexTTS-2
+
+2-stage TTS pipeline (GPT AR talker + S2Mel CFM DiT + BigVGAN vocoder) at 22.05 kHz. Every request requires reference audio for zero-shot voice cloning. Supports emotion conditioning via audio, text, or 8-dim vector.
+
+### Quick start
+```bash
+python examples/offline_inference/text_to_speech/indextts2/end2end.py \
+    --model IndexTeam/IndexTTS-2 \
+    --text "你好，这是一个语音合成测试。" \
+    --ref-audio /path/to/reference.wav
+```
+
+### Emotion control
+```bash
+# Emotion from reference audio
+python examples/offline_inference/text_to_speech/indextts2/end2end.py \
+    --model IndexTeam/IndexTTS-2 \
+    --text "今天天气真好！" \
+    --ref-audio /path/to/ref.wav \
+    --emo-audio /path/to/happy.wav
+
+# Emotion from 8-dim vector (happy angry sad afraid disgusted melancholy surprised calm)
+python examples/offline_inference/text_to_speech/indextts2/end2end.py \
+    --model IndexTeam/IndexTTS-2 \
+    --text "今天天气真好！" \
+    --ref-audio /path/to/ref.wav \
+    --emo-vector 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
+
+# Emotion from text description
+python examples/offline_inference/text_to_speech/indextts2/end2end.py \
+    --model IndexTeam/IndexTTS-2 \
+    --text "今天天气真好！" \
+    --ref-audio /path/to/ref.wav \
+    --emo-text "happy and excited"
+```
+
+### Notes
+- `--ref-audio` is **required** — IndexTTS-2 does not support text-only synthesis.
+- Stage 0 (AR Talker): GPT-2 generates mel codes from text + reference audio.
+- Stage 1 (S2Mel + BigVGAN): CFM DiT converts mel codes to waveform at 22.05 kHz.
+- Deploy config: `vllm_omni/deploy/indextts2.yaml`. Stage 1 runs with `enforce_eager: true` (DiT has dynamic shapes).
+
+---
+
 ## Voxtral TTS
 
 Voxtral-4B-TTS (Mistral). Has its own argparse surface; uses voice presets and the `mistral_common` `SpeechRequest` protocol.