php使用ffmpeg向视频中添加文字字幕的实现方法

<?php 
$dir = './'; // set to current folder 
if ($handle = opendir($dir)) { 
 while(false!== ($file = readdir($handle))) { 
 if ( is_file($dir.$file) ){ 
 if (preg_match("'\.(avi)$'", $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('input.avi', 'input.srt', 'output.jpg', 'output.ogm'); 
// code provided and updated by steve of phpsnaps ! thanks 
// aepts: 
// 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 
 $cmd = 'ffmpeg -v 0 -y -i '.$in.' -vframes 1 -ss 250 -vcodec mjpeg -f rawvideo -s 286x160 -aspect 16:9 '.$out_thumb; 
 $res = shell_exec($cmd); 
 // $res is the output of the mand 
 // transcode video 
$cmd = 'mencoder '.$in.' -o '.$out_vid.' -sub '.$in_sub.' -subfont-text-scale 3.0 -subpos 99 -af volume=10 -aspect 16:9 -of avi -noodml -ovc x264 -x264encop$ 
 $res = shell_exec($cmd); 
} 
?>