"""TTS flow helpers extracted from the duplex pipeline.

This module is intentionally lightweight for phase-wise migration.
"""

from __future__ import annotations

from providers.common.base import TTSChunk


def chunk_duration_ms(chunk: TTSChunk) -> float:
    """Estimate chunk duration in milliseconds for pcm16 mono."""
    if chunk.sample_rate <= 0:
        return 0.0
    return (len(chunk.audio) / 2.0 / float(chunk.sample_rate)) * 1000.0