[Qwen3TTS][Feat] Streaming output (#1438)

Signed-off-by: pablo <pablo@agigo.ai>
Signed-off-by: Hongsheng Liu <liuhongsheng4@huawei.com>
Co-authored-by: pablo <pablo@agigo.ai>
Co-authored-by: Hongsheng Liu <liuhongsheng4@huawei.com>

examples/online_serving/qwen3_tts/README.md

@@ -146,7 +146,8 @@ Lists available voices for the loaded model:
     "ref_audio": "URL or base64 for voice cloning",
     "ref_text": "Reference audio transcript",
     "x_vector_only_mode": false,
-    "max_new_tokens": 2048
+    "max_new_tokens": 2048,
+    "stream": false
 }
 ```
 
@@ -166,7 +167,7 @@ Returns audio data in the requested format (default: WAV).
 | `model` | string | server's model | Model to use (optional, should match server if specified) |
 | `voice` | string | "vivian" | Speaker name (e.g., vivian, ryan, aiden) |
 | `response_format` | string | "wav" | Audio format: wav, mp3, flac, pcm, aac, opus |
-| `speed` | float | 1.0 | Playback speed (0.25-4.0) |
+| `speed` | float | 1.0 | Playback speed (0.25-4.0, not supported with `stream=true`) |
 
 ### vLLM-Omni Extension Parameters
 
@@ -176,6 +177,7 @@ Returns audio data in the requested format (default: WAV).
 | `language` | string | "Auto" | Language (see supported languages below) |
 | `instructions` | string | "" | Voice style/emotion instructions |
 | `max_new_tokens` | int | 2048 | Maximum tokens to generate |
+| `stream` | bool | false | Stream raw PCM chunks as they are decoded (requires `response_format="pcm"`) |
 
 **Supported languages:** Auto, Chinese, English, Japanese, Korean, German, French, Russian, Portuguese, Spanish, Italian
 
@@ -224,9 +226,37 @@ with open("output.wav", "wb") as f:
     f.write(response.content)
 ```
 
+## Streaming
+
+Set `stream=true` with `response_format="pcm"` to receive raw PCM audio chunks as they are decoded
+(one chunk per 25-frame Code2Wav window, ~2 s latency to first byte):
+
+```bash
+# Stream raw PCM and pipe directly to a player
+curl -X POST http://localhost:8091/v1/audio/speech \
+    -H "Content-Type: application/json" \
+    -d '{
+        "input": "Hello, how are you?",
+        "voice": "vivian",
+        "language": "English",
+        "stream": true,
+        "response_format": "pcm"
+    }' --no-buffer | play -t raw -r 24000 -e signed -b 16 -c 1 -
+
+# Or save the raw PCM for offline processing
+curl -X POST http://localhost:8091/v1/audio/speech \
+    -H "Content-Type: application/json" \
+    -d '{"input": "Hello!", "stream": true, "response_format": "pcm"}' \
+    --output output.pcm
+```
+
+**Constraints:**
+- `stream=true` requires `response_format="pcm"` (raw 16-bit signed PCM, 24 kHz mono).
+- `speed` adjustment is not supported when streaming (`speed` must be 1.0 or omitted).
+- Requires the server to be launched with a stage config that sets `async_chunk: true`.
+
 ## Limitations
 
-- **No streaming**: Audio is generated completely before being returned. Streaming will be supported after the pipeline is disaggregated (see RFC #938).
 - **Single request**: Batch processing is not yet optimized for online serving.
 
 ## Troubleshooting