main.py

import json
import math
import sys
from datetime import timedelta

def format_ms(ms):
    remainder, milliseconds = divmod(ms, 1000)
    remainder, seconds = divmod(remainder, 60)
    hours, minutes = divmod(remainder, 60)
    return '{:02}:{:02}:{:02}.{:03}'.format(int(hours), int(minutes), int(seconds), int(milliseconds))

def make_vtt(filename):
    f = open(filename, "r")
    data = json.load(f)

    string = "WEBVTT\n\n"

    start_ms = -1
    sentence = ""
    for word in data["words"]:
        if start_ms == -1:
            start_ms = word["start"]
        last_char = word["text"][-1]
        if last_char == "." or last_char == "!" or last_char == "?":
            sentence += word["text"]
            string += "\n"
            string += f'{format_ms(start_ms)} --> {format_ms(word["end"])}'
            string += "\n"
            string += sentence
            string += "\n"
            start_ms = -1
            sentence = ""
        else:
            sentence += word["text"] + " "

    return string

print(make_vtt(sys.argv[1]))