PHP实现获取FLV文件的时间

<?php
functionbigendian2int($byte_word,$signed=false)
{
    $int_value    =0;
    $byte_wordlen=strlen($byte_word);
    for($i=0;$i<$byte_wordlen;$i++){
        $int_value+=ord($byte_word{$i})*pow(256,($byte_wordlen-1-$i));
    }
    if($signed){
        $sign_mask_bit=0x80<<(8*($byte_wordlen-1));
        if($int_value&$sign_mask_bit){
            $int_value=0-($int_value&($sign_mask_bit-1));
        }
    }
    return$int_value;
}
 
functiongettime($name)
{
    if(!file_exists($name)){
        return;
    }
    $flv_data_length=filesize($name);
    $fp              =@fopen($name,'rb');
    $flv_header      =fread($fp,5);
    fseek($fp,5,seek_set);
    $frame_size_data_length  =bigendian2int(fread($fp,4));
    $flv_header_frame_length=9;
    if($frame_size_data_length>$flv_header_frame_length){
        fseek($fp,$frame_size_data_length-$flv_header_frame_length,seek_cur);
    }
    $duration=0;
    while((ftell($fp)+1)<$flv_data_length){
        $this_tag_header=fread($fp,16);
        $data_length     =bigendian2int(substr($this_tag_header,5,3));
        $timestamp       =bigendian2int(substr($this_tag_header,8,3));
        $next_offset     =ftell($fp)-1+$data_length;
        if($timestamp>$duration){
            $duration=$timestamp;
        }
        fseek($fp,$next_offset,seek_set);
    }
    fclose($fp);
    return$duration;
}
 
functionget_flv_file_time($time)
{
$time=gettime($time);
    $num=$time;
    $sec=intval($num/1000);
    $h   =intval($sec/3600);
    $m   =intval(($sec%3600)/60);
    $s   =intval(($sec%60));
    $tm  =$h.':'.$m.':'.$s;
    return$tm;
}
 
?>