YouTube Subtitles - XML to SRT

tt2srt.php

<?php

$argv = [
'',
'filename.xml'
];

if(empty($argv[1])) {
	exit('Argument one must contain the TimedText file.');
}

if(empty($argv[2])) {
	$argv[2] = str_replace('.xml', '.srt', $argv[1]);
}

$ttfile = __DIR__ . '/'. $argv[1];
$srtfile = __DIR__ . '/'. $argv[2];

$dom = new DOMDocument;

// Prevent DOMDocument::loadHTML error
libxml_use_internal_errors(true);

$dom->loadXML(file_get_contents($ttfile));

function srt_timestamp($seconds, $is_miliseconds = false) {
	if($is_miliseconds) {
		$milliseconds = $seconds * 1000;
	} else {
		$milliseconds = $seconds;
	}

    $seconds = floor($milliseconds / 1000);
    $minutes = floor($seconds / 60);
    $hours = floor($minutes / 60);
    $milliseconds = $milliseconds % 1000;
    $seconds = $seconds % 60;
    $minutes = $minutes % 60;
    return ($hours < 10 ? '0' : '') . $hours . ':'
        . ($minutes < 10 ? '0' : '') . $minutes . ':'
        . ($seconds < 10 ? '0' : '') . $seconds . ','
        . ($milliseconds < 100 ? '0' : '') . ($milliseconds < 10 ? '0' : '') . $milliseconds;
}

$constents = '';

foreach ($dom->getElementsByTagName('p') as $k => $sub) {
	$constents .= srt_timestamp($sub->getAttribute('t')) . ' --> ';
	$constents .= srt_timestamp($sub->getAttribute('t') + $sub->getAttribute('d')) . PHP_EOL;
	$constents .= $sub->nodeValue . PHP_EOL;
	$constents .= PHP_EOL;
}

foreach ($dom->getElementsByTagName('text') as $k => $sub) {
	$constents .= srt_timestamp($sub->getAttribute('start'),true) . ' --> ';
	$constents .= srt_timestamp($sub->getAttribute('start') + $sub->getAttribute('dur'),true) . PHP_EOL;
	$constents .= trim(html_entity_decode($sub->nodeValue)) . PHP_EOL;
	$constents .= PHP_EOL;
}

file_put_contents($srtfile, $constents);