[Bugfix] Fix all-silence TTS output: use float32 for speech tokenizer decoder (#1664)

Signed-off-by: Zhanqiu Hu <zh338@cornell.edu>
Co-authored-by: Yueqian Lin <70319226+linyueqian@users.noreply.github.com>

tests/e2e/online_serving/test_qwen3_tts_base.py

@@ -0,0 +1,167 @@
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+"""
+E2E tests for Qwen3-TTS Base voice-clone model.
+
+Regression test for #1663: speech tokenizer loaded in bfloat16 produced
+all-silence PCM due to NaN overflow in SnakeBeta activation.
+"""
+
+import os
+
+os.environ["VLLM_WORKER_MULTIPROC_METHOD"] = "spawn"
+os.environ["VLLM_TEST_CLEAN_GPU_MEMORY"] = "0"
+
+import struct
+import tempfile
+from pathlib import Path
+
+import httpx
+import pytest
+
+from tests.conftest import (
+    OmniServer,
+    convert_audio_file_to_text,
+    cosine_similarity_text,
+)
+from tests.utils import hardware_test
+
+MODEL = "Qwen/Qwen3-TTS-12Hz-1.7B-Base"
+
+# Official Qwen3-TTS reference audio/text from examples/offline_inference/qwen3_tts/end2end.py
+REF_AUDIO_URL = "https://qianwen-res.oss-cn-beijing.aliyuncs.com/Qwen3-TTS-Repo/clone_2.wav"
+REF_TEXT = "Okay. Yeah. I resent you. I love you. I respect you. But you know what? You blew it! And thanks to you."
+SYN_TEXT = "Good one. Okay, fine, I'm just gonna leave this sock monkey here. Goodbye."
+
+
+def get_stage_config():
+    return str(
+        Path(__file__).parent.parent.parent.parent / "vllm_omni" / "model_executor" / "stage_configs" / "qwen3_tts.yaml"
+    )
+
+
+@pytest.fixture(scope="module")
+def omni_server():
+    """Start vLLM-Omni server with Base voice-clone model."""
+    stage_config_path = get_stage_config()
+
+    with OmniServer(
+        MODEL,
+        [
+            "--stage-configs-path",
+            stage_config_path,
+            "--stage-init-timeout",
+            "120",
+            "--trust-remote-code",
+            "--enforce-eager",
+            "--disable-log-stats",
+        ],
+    ) as server:
+        yield server
+
+
+def make_base_speech_request(
+    host: str,
+    port: int,
+    text: str = SYN_TEXT,
+    ref_text: str = REF_TEXT,
+    ref_audio: str = REF_AUDIO_URL,
+    response_format: str = "wav",
+    timeout: float = 120.0,
+) -> httpx.Response:
+    url = f"http://{host}:{port}/v1/audio/speech"
+    payload = {
+        "model": MODEL,
+        "input": text,
+        "task_type": "Base",
+        "ref_text": ref_text,
+        "ref_audio": ref_audio,
+        "response_format": response_format,
+    }
+    with httpx.Client(timeout=timeout) as client:
+        return client.post(url, json=payload)
+
+
+def verify_wav_audio(content: bytes) -> bool:
+    if len(content) < 44:
+        return False
+    return content[:4] == b"RIFF" and content[8:12] == b"WAVE"
+
+
+def assert_not_silence(pcm_bytes: bytes):
+    """Assert PCM16 samples are not all identical (e.g. all-silence)."""
+    samples = struct.unpack(f"<{len(pcm_bytes) // 2}h", pcm_bytes)
+    unique = set(samples)
+    assert len(unique) > 1, (
+        f"All-silence detected: {len(samples)} samples, unique values: {unique}. "
+        "See https://github.com/vllm-project/vllm-omni/issues/1663"
+    )
+
+
+MIN_AUDIO_BYTES = 10000
+
+
+class TestQwen3TTSBaseVoiceClone:
+    """Regression tests for Base voice-clone (fix #1663)."""
+
+    @pytest.mark.core_model
+    @pytest.mark.omni
+    @hardware_test(res={"cuda": "L4"}, num_cards=4)
+    def test_base_voice_clone_not_silence(self, omni_server) -> None:
+        """PCM output must contain real audio, not all-silence."""
+        response = make_base_speech_request(
+            host=omni_server.host,
+            port=omni_server.port,
+            response_format="pcm",
+        )
+
+        assert response.status_code == 200, f"Request failed: {response.text}"
+        assert len(response.content) > MIN_AUDIO_BYTES, f"Audio too small: {len(response.content)} bytes"
+        assert_not_silence(response.content)
+
+    @pytest.mark.core_model
+    @pytest.mark.omni
+    @hardware_test(res={"cuda": "L4"}, num_cards=4)
+    def test_base_voice_clone_whisper_transcription(self, omni_server) -> None:
+        """Whisper must transcribe the output as intelligible speech."""
+        response = make_base_speech_request(
+            host=omni_server.host,
+            port=omni_server.port,
+            response_format="wav",
+        )
+
+        assert response.status_code == 200, f"Request failed: {response.text}"
+        assert verify_wav_audio(response.content), "Response is not valid WAV"
+        assert len(response.content) > MIN_AUDIO_BYTES
+
+        with tempfile.NamedTemporaryFile(suffix=".wav", delete=False) as f:
+            f.write(response.content)
+            wav_path = f.name
+
+        try:
+            transcript = convert_audio_file_to_text(wav_path)
+            print(f"Whisper transcript: {transcript}")
+            assert len(transcript.strip()) > 0, "Whisper returned empty transcript — audio is likely silence"
+            similarity = cosine_similarity_text(transcript.lower(), SYN_TEXT.lower())
+            print(f"Cosine similarity: {similarity:.3f}")
+            assert similarity > 0.9, (
+                f"Transcript doesn't match input: similarity={similarity:.2f}, transcript='{transcript}'"
+            )
+        finally:
+            os.unlink(wav_path)
+
+    @pytest.mark.core_model
+    @pytest.mark.omni
+    @hardware_test(res={"cuda": "L4"}, num_cards=4)
+    def test_base_voice_clone_wav_format(self, omni_server) -> None:
+        """WAV response must have valid headers and sufficient size."""
+        response = make_base_speech_request(
+            host=omni_server.host,
+            port=omni_server.port,
+            response_format="wav",
+        )
+
+        assert response.status_code == 200, f"Request failed: {response.text}"
+        assert response.headers.get("content-type") == "audio/wav"
+        assert verify_wav_audio(response.content), "Response is not valid WAV"
+        assert len(response.content) > MIN_AUDIO_BYTES

vllm_omni/model_executor/models/qwen3_tts/qwen3_tts_code2wav.py

@@ -73,7 +73,7 @@ class Qwen3TTSCode2Wav(nn.Module):
 
         tok = Qwen3TTSTokenizer.from_pretrained(
             speech_tokenizer_dir,
-            torch_dtype=torch.bfloat16,
+            torch_dtype=torch.float32,
             load_feature_extractor=False,
         )