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vllm-omni/vllm_omni/model_executor/models/indextts2/prompt_utils.py
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# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
"""Prompt helpers for IndexTTS2 talker prefill."""
from __future__ import annotations
from functools import lru_cache
from vllm_omni.model_executor.models.indextts2.preprocess_utils import resolve_model_file
from vllm_omni.model_executor.models.indextts2.tokenizer import IndexTTS2Tokenizer
_CONDITIONING_PREFIX_TOKENS = 34
_TEXT_WRAPPER_TOKENS = 2
_START_MEL_TOKENS = 1
def _resolve_bpe_model_path(model_id_or_path: str) -> str:
path = resolve_model_file(model_id_or_path, "bpe.model")
if path is None:
raise FileNotFoundError(f"Could not resolve bpe.model for {model_id_or_path!r}")
return path
@lru_cache(maxsize=16)
def _get_text_tokenizer(model_id_or_path: str) -> IndexTTS2Tokenizer:
return IndexTTS2Tokenizer(_resolve_bpe_model_path(model_id_or_path), model_dir=model_id_or_path)
def estimate_indextts2_prefill_prompt_len(model_id_or_path: str, text: str) -> int:
"""Return the placeholder prompt length expected by the IndexTTS2 talker.
The model-side prefill replaces placeholder embeddings with:
34 conditioning tokens, text tokens wrapped with start/stop markers, and
one start-mel token.
"""
tokenizer = _get_text_tokenizer(model_id_or_path)
text_token_count = len(tokenizer.encode(text, add_special_tokens=False)) + _TEXT_WRAPPER_TOKENS
return _CONDITIONING_PREFIX_TOKENS + text_token_count + _START_MEL_TOKENS
def build_indextts2_prefill_prompt_ids(
model_id_or_path: str,
text: str,
*,
placeholder_token_id: int = 1,
) -> list[int]:
return [placeholder_token_id] * estimate_indextts2_prefill_prompt_len(model_id_or_path, text)