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vllm-omni/vllm_omni/entrypoints/openai/tts_adapters/audex.py
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# SPDX-License-Identifier: Apache-2.0
"""Audex (Nemotron-Labs-Audex-2B) TTS serving adapter."""
from typing import TYPE_CHECKING, Any
from vllm_omni.entrypoints.openai.tts_adapters import register_tts_adapter
from vllm_omni.entrypoints.openai.tts_adapters.base import ARTTSAdapter, PreparedRequest, apply_max_new_tokens
from vllm_omni.model_executor.models.audex.prompt import build_cond_prompt
if TYPE_CHECKING:
from vllm_omni.entrypoints.openai.protocol.audio import OpenAICreateSpeechRequest
# Classifier-free guidance strength accepted on /v1/audio/speech via
# extra_params. 1.0 disables guidance (identical to omitting it); the
# official TTS quality setting is 1.5.
AUDEX_CFG_SCALE_MIN = 1.0
AUDEX_CFG_SCALE_MAX = 10.0
# Internal CFG pair-plumbing keys; injected by this adapter once it receives
# the final request id, never accepted from callers.
_AUDEX_INTERNAL_CFG_KEYS = ("cfg_role", "cfg_pair_id", "cfg_null_prompt")
@register_tts_adapter
class AudexAdapter(ARTTSAdapter):
"""Plain English TTS: single built-in voice, no reference audio, optional CFG."""
stage_keys = frozenset({"audex_thinker", "audex_omni"})
name = "audex"
@classmethod
def stage_serves_speech(cls, model_stage: str | None, all_stage_keys: frozenset[str]) -> bool:
"""``audex_omni`` covers the audex_s2s deployment, whose TTS pass uses
the same ``/v1/audio/speech`` surface. Without the speech decoder the
same thinker is text-final and must not accept speech requests."""
if model_stage == "audex_omni":
return "audex_code2wav" in all_stage_keys
return True
def validate(self, request: "OpenAICreateSpeechRequest") -> str | None:
if not request.input or not request.input.strip():
return "Audex TTS requires non-empty input text"
voice = (request.voice or "").strip().lower()
if voice not in ("", "default"):
return (
f"Audex has a single built-in voice and no voice cloning; got voice={request.voice!r}. "
"Omit 'voice' or pass 'default'."
)
if request.ref_audio is not None:
return "Audex does not support reference audio (no voice cloning)."
extra = request.extra_params or {}
for key in _AUDEX_INTERNAL_CFG_KEYS:
if key in extra:
return f"extra_params.{key} is managed internally by the server; only cfg_scale may be set."
cfg_scale = extra.get("cfg_scale")
if cfg_scale is not None:
try:
cfg_value = float(cfg_scale)
except (TypeError, ValueError):
return (
f"extra_params.cfg_scale must be a number in "
f"[{AUDEX_CFG_SCALE_MIN}, {AUDEX_CFG_SCALE_MAX}]; got {cfg_scale!r}."
)
if not (AUDEX_CFG_SCALE_MIN <= cfg_value <= AUDEX_CFG_SCALE_MAX):
return (
f"extra_params.cfg_scale must be within [{AUDEX_CFG_SCALE_MIN}, {AUDEX_CFG_SCALE_MAX}]; "
f"got {cfg_scale!r}. 1.0 disables guidance; 1.5 is the recommended quality setting."
)
return None
async def build(
self, request: "OpenAICreateSpeechRequest", sampling_params_list: list, has_inline_ref_audio: bool
) -> PreparedRequest:
prompt = {"prompt": build_cond_prompt(request.input)}
return PreparedRequest(prompt=prompt, tts_params={}, model_type="audex")
def apply_sampling_overrides(
self,
sampling_params_list: list,
request: "OpenAICreateSpeechRequest",
prompt: dict[str, Any] | None = None,
request_id: str | None = None,
) -> list:
if request_id is None:
raise ValueError("Audex CFG requires a request id")
stage0_params = sampling_params_list[0]
sampling_params_list[0] = self._inject_audex_cfg_pair_args(
request_id=request_id, prompt=prompt, stage0_params=stage0_params
)
return apply_max_new_tokens(sampling_params_list, request)
def _inject_audex_cfg_pair_args(self, request_id: str, prompt: Any, stage0_params: Any) -> Any:
"""Complete the Audex CFG contract on a CLONE of the stage-0 params.
The adapter validated ``cfg_scale``; here (where the final request id
exists) the cond role, pair id, and the length-matched null prompt are
attached. ``cfg_scale`` absent/1.0 returns a clone value-identical to
the non-CFG flow (the key is dropped rather than forwarded).
Returns the cloned params; the input is never mutated (it may be an
element of the engine's shared ``default_sampling_params_list`` —
see ``_inject_audex_tta_args``).
"""
server = self.ctx.server
import copy
stage0_params = copy.deepcopy(stage0_params)
extra_args = getattr(stage0_params, "extra_args", None)
if not extra_args or extra_args.get("cfg_scale") is None:
if extra_args:
extra_args.pop("cfg_scale", None)
return stage0_params
cfg_scale = float(extra_args["cfg_scale"])
if cfg_scale <= 1.0:
extra_args.pop("cfg_scale", None)
return stage0_params
from vllm_omni.model_executor.models.audex.prompt import build_null_prompt
cond_prompt = prompt.get("prompt") if isinstance(prompt, dict) else prompt
if not isinstance(cond_prompt, str) or not cond_prompt:
raise ValueError("Audex CFG requires the adapter-built text prompt")
null_prompt = build_null_prompt(cond_prompt, server._get_audex_tokenizer())
extra_args.update(
{
"cfg_scale": cfg_scale,
"cfg_role": "cond",
"cfg_pair_id": request_id,
"cfg_null_prompt": null_prompt,
}
)
# Guided decoding sharpens the distribution; the unguided default
# temperature (0.1) adds excess sampling noise under CFG. Measured
# on the en-24 gate corpus at cfg 1.5: temp 0.1 -> CER 7.31%,
# temp 0.05 -> CER 6.87% (unguided baseline 7.24%).
stage0_params.temperature = 0.05
return stage0_params