PHP使用FFMPEG创建视频缩略图 - 返回错误代码1

Question

我正在尝试使用以下脚本使用FFMPEG创建视频缩略图。 但是我得到的返回值为1.这是什么意思？什么是错误代码1？我用谷歌搜索它并没有找到并回答。谢谢。 这是代码：

<?php

        //thumb path should be added in the below code
        //test for thumb
        $dir_img='uploads/';
        $mediapath='thumb.jpg';
        $file_thumb=create_movie_thumb('test.mp4',$mediapath,$mediaid);

        $name_file=explode(".",$mediapath);
        $imgname="thumb_".$name_file[0].".jpg";     

        /*
          Function to create video thumbnail using ffmpeg
        */
        function create_movie_thumb($src_file,$mediapath,$mediaid)
        {

            global $CONFIG, $ERROR;

            $CONFIG['ffmpeg_path'] = '/usr/bin/'; // Change the path according to your server.
            $dir_img='uploads/';
            $CONFIG['fullpath'] = $dir_img."thumbs/";

            $src_file = $src_file;
            $name_file=explode(".",$mediapath);
            $imgname="thumb_".$name_file[0].".jpg";
            $dest_file = $CONFIG['fullpath'].$imgname;

            if (preg_match("#[A-Z]:|\\\\#Ai", __FILE__)) {
                // get the basedir, remove '/include'
                $cur_dir = substr(dirname(__FILE__), 0, -8);
                $src_file = '"' . $cur_dir . '\\' . strtr($src_file, '/', '\\') . '"';
                $ff_dest_file = '"' . $cur_dir . '\\' . strtr($dest_file, '/', '\\') . '"';
            } else {
                $src_file = escapeshellarg($src_file);
                $ff_dest_file = escapeshellarg($dest_file);
            }

            $output = array();

            if (eregi("win",$_ENV['OS'])) {
                // Command to create video thumb
                $cmd = "\"".str_replace("\\","/", $CONFIG['ffmpeg_path'])."ffmpeg\" -i ".str_replace("\\","/" ,$src_file )." -an -ss 00:00:05 -r 1 -vframes 1 -y ".str_replace("\\","/" ,$ff_dest_file);
                exec ("\"$cmd\"", $output, $retval);
                echo "exec1";

            } else {
                // Command to create video thumb
                $cmd = "{$CONFIG['ffmpeg_path']}ffmpeg -i $src_file -an -ss 00:00:05 -r 1 -vframes 1 -y $ff_dest_file";
                exec ($cmd, $output, $retval);
                echo "exec2";
            }


            if ($retval) {
                $ERROR = "Error executing FFmpeg - Return value: $retval";
                if ($CONFIG['debug_mode']) {
                    // Re-execute the command with the backtick operator in order to get all outputs
                    // will not work if safe mode is enabled
                    $output = `$cmd 2>&1`;
                    $ERROR .= "<br /><br /><div align=\"left\">Cmd line : <br /><span style=\"font-size:120%\">" . nl2br(htmlspecialchars($cmd)) . "</span></div>";
                    $ERROR .= "<br /><br /><div align=\"left\">The ffmpeg program said:<br /><span style=\"font-size:120%\">";
                    $ERROR .= nl2br(htmlspecialchars($output));
                    $ERROR .= "</span></div>";
                }
                echo $ERROR;
                @unlink($dest_file);
                return false;
            }

            $return = $dest_file;
            //@chmod($return, octdec($CONFIG['default_file_mode'])); //silence the output in case chmod is disabled
            return $return;
        } 
?>