TSの先頭80秒のstreamパターン変化を読み取り、変化があった時間を返す

ts_check.php

<?php
/**
 * streamの変化を調べる
 * @url http://zion009.blog98.fc2.com/blog-entry-36.html
 */

$src = $argv[1];
$temp_file = '/tmp/tmp.mp4';
$temp_text = '/tmp/tmp.text';

$cmd = "ffmpeg -i {$src} -y -v verbose -t 80 -s 128x96 {$temp_file} 2> {$temp_text}";

exec($cmd);

function get_offset($temp_text)
{
    $is_capture = false;
    $result = array();
    foreach (file($temp_text) as $line) {
        if (strpos($line, 'frame changed from') !== false) {
            $is_capture = true;
        }   

        if ($is_capture === true) {
            $result[] = $line;
            $regex_result = preg_match('_time=00:(\d\d:\d\d.\d\d)_', $line, $matches);
            //if (strpos($line, 'time') !== false) {
            if ($regex_result) {
                $parts = explode(':', $matches[1]);
                $offset = ($parts[0] * 60) + ceil($parts[1]) + 1;
                return (int)$offset;
            }   
        }   
    }   
    return 0;
}

echo get_offset($temp_text);