PHPを使用してffmpegを使用してビデオに字幕を追加する方法

<?php
$dir = &#39;./&#39;; // set to current folder
if ($handle = opendir($dir)) {
 while(false!== ($file = readdir($handle))) {
 if ( is_file($dir.$file) ){
 if (preg_match("&#39;\.(avi)$&#39;", $file) ){
 $sub_file = str_ireplace(".avi", ".srt", $dir.$file);
 $idx_file = str_ireplace(".avi", ".idx", $dir.$file);
 $thumb_file = str_ireplace(".avi", ".jpg", $dir.$file);
 $out_file = str_ireplace(".avi", ".mp4", $dir.$file);
 flv_convert_get_thumb($dir.$file, $sub_file, $idx_file, $thumb_file, $out_file);
 }
 else{
 continue;
 }
 }
 }
 closedir($handle);
}
//flv_convert_get_thumb(&#39;input.avi&#39;, &#39;input.srt&#39;, &#39;output.jpg&#39;, &#39;output.ogm&#39;);
// code provided and updated by steve of phpsnaps ! thanks
// accepts:
// 1: the input video file
// 2: path to thumb jpg
// 3: path to transcoded mpeg?
function flv_convert_get_thumb($in, $in_sub, $in_idx, $out_thumb, $out_vid){
 // get thumbnail
 $cmd = &#39;ffmpeg -v 0 -y -i &#39;.$in.&#39; -vframes 1 -ss 250 -vcodec mjpeg -f rawvideo -s 286x160 -aspect 16:9 &#39;.$out_thumb;
 $res = shell_exec($cmd);
 // $res is the output of the command
 // transcode video
$cmd = &#39;mencoder &#39;.$in.&#39; -o &#39;.$out_vid.&#39; -sub &#39;.$in_sub.&#39; -subfont-text-scale 3.0 -subpos 99 -af volume=10 -aspect 16:9 -of avi -noodml -ovc x264 -x264encop$
 $res = shell_exec($cmd);
}
?>