js-tts-wrapper/cjs/utils/word-timing-estimator.js

A JavaScript/TypeScript library that provides a unified API for working with multiple cloud-based Text-to-Speech (TTS) services

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.estimateWordBoundaries = estimateWordBoundaries;
/**
 * Estimate word boundaries for a given text
 *
 * This is a simple estimator that assumes a constant speaking rate.
 * It's not accurate but provides a reasonable approximation when
 * the TTS engine doesn't provide word boundary information.
 *
 * @param text Text to estimate word boundaries for
 * @param options Options for estimation
 * @returns Array of word boundary objects
 */
function estimateWordBoundaries(text, options = {}) {
    // Default options
    const wordsPerMinute = options.wordsPerMinute || 150; // Average speaking rate
    const startTime = options.startTime || 0;
    // Split text into words
    const words = text.split(/\s+/).filter((word) => word.length > 0);
    // Calculate time per word in milliseconds
    const msPerWord = (60 * 1000) / wordsPerMinute;
    // Generate word boundaries
    const wordBoundaries = [];
    let currentTime = startTime;
    for (const word of words) {
        // Estimate duration based on word length
        // Longer words take more time to pronounce
        const lengthFactor = Math.max(0.5, Math.min(2.0, word.length / 5));
        const duration = msPerWord * lengthFactor;
        wordBoundaries.push({
            word,
            start: currentTime / 1000, // Convert to seconds
            end: (currentTime + duration) / 1000, // Convert to seconds
        });
        currentTime += duration;
    }
    return wordBoundaries;
}