PHPでmp3オーディオ情報を取得するチュートリアルの例

#php mp3 オーディオ情報の取得

昔、MP3 を取得するための php クラスをインターネット上で見ました。オーディオ情報。例: 再生時間、ファイル サイズ、ファイル エンコーディングなど。

<?php
class mp3file
{
    protected $block;
    protected $blockpos;
    protected $blockmax;
    protected $blocksize;
    protected $fd;
    protected $bitpos;
    protected $mp3data;
    public function __construct($filename)
    {
        $this->powarr  = array(0=>1,1=>2,2=>4,3=>8,4=>16,5=>32,6=>64,7=>128);
        $this->blockmax= 1024;
        
        $this->mp3data = array();
        $this->mp3data[&#39;Filesize&#39;] = filesize($filename);
        $this->fd = fopen($filename,&#39;rb&#39;);
        $this->prefetchblock();
        $this->readmp3frame();
    }
    public function __destruct()
    {
        fclose($this->fd);
    }
    //-------------------
    public function get_metadata()
    {
        return $this->mp3data;
    }
    protected function readmp3frame()
    {
        $iscbrmp3=true;
        if ($this->startswithid3())
            $this->skipid3tag();
        else if ($this->containsvbrxing())
        {
            $this->mp3data[&#39;Encoding&#39;] = &#39;VBR&#39;;
            $iscbrmp3=false;
        }
        else if ($this->startswithpk())
        {
            $this->mp3data[&#39;Encoding&#39;] = &#39;Unknown&#39;;
            $iscbrmp3=false;
        }
    
        if ($iscbrmp3)
        {
            $i = 0;
            $max=5000;
            //look in 5000 bytes... 
            //the largest framesize is 4609bytes(256kbps@8000Hz  mp3)
            for($i=0; $i<$max; $i++)
            {
                //looking for 1111 1111 111 (frame synchronization bits)                
                if ($this->getnextbyte()==0xFF)
                    if ($this->getnextbit() && $this->getnextbit() && $this->getnextbit())
                        break;
            }
            if ($i==$max)
                $iscbrmp3=false;
        }
    
        if ($iscbrmp3)
        {
            $this->mp3data[&#39;Encoding&#39;         ] = &#39;CBR&#39;;
            $this->mp3data[&#39;MPEG version&#39;     ] = $this->getnextbits(2);
            $this->mp3data[&#39;Layer Description&#39;] = $this->getnextbits(2);
            $this->mp3data[&#39;Protection Bit&#39;   ] = $this->getnextbits(1);
            $this->mp3data[&#39;Bitrate Index&#39;    ] = $this->getnextbits(4);
            $this->mp3data[&#39;Sampling Freq Idx&#39;] = $this->getnextbits(2);
            $this->mp3data[&#39;Padding Bit&#39;      ] = $this->getnextbits(1);
            $this->mp3data[&#39;Private Bit&#39;      ] = $this->getnextbits(1);
            $this->mp3data[&#39;Channel Mode&#39;     ] = $this->getnextbits(2);
            $this->mp3data[&#39;Mode Extension&#39;   ] = $this->getnextbits(2);
            $this->mp3data[&#39;Copyright&#39;        ] = $this->getnextbits(1);
            $this->mp3data[&#39;Original Media&#39;   ] = $this->getnextbits(1);
            $this->mp3data[&#39;Emphasis&#39;         ] = $this->getnextbits(1);
            $this->mp3data[&#39;Bitrate&#39;          ] = mp3file::bitratelookup($this->mp3data);
            $this->mp3data[&#39;Sampling Rate&#39;    ] = mp3file::samplelookup($this->mp3data);
            $this->mp3data[&#39;Frame Size&#39;       ] = mp3file::getframesize($this->mp3data);
            $this->mp3data[&#39;Length&#39;           ] = mp3file::getduration($this->mp3data,$this->tell2());
            $this->mp3data[&#39;Length mm:ss&#39;     ] = mp3file::seconds_to_mmss($this->mp3data[&#39;Length&#39;]);
            
            if ($this->mp3data[&#39;Bitrate&#39;      ]==&#39;bad&#39;     ||
                $this->mp3data[&#39;Bitrate&#39;      ]==&#39;free&#39;    ||
                $this->mp3data[&#39;Sampling Rate&#39;]==&#39;unknown&#39; ||
                $this->mp3data[&#39;Frame Size&#39;   ]==&#39;unknown&#39; ||
                $this->mp3data[&#39;Length&#39;     ]==&#39;unknown&#39;)
            $this->mp3data = array(&#39;Filesize&#39;=>$this->mp3data[&#39;Filesize&#39;], &#39;Encoding&#39;=>&#39;Unknown&#39;);
        }
        else
        {
            if(!isset($this->mp3data[&#39;Encoding&#39;]))
                $this->mp3data[&#39;Encoding&#39;] = &#39;Unknown&#39;;
        }
    }
    protected function tell()
    {
        return ftell($this->fd);
    }
    protected function tell2()
    {
        return ftell($this->fd)-$this->blockmax +$this->blockpos-1;
    }
    protected function startswithid3()
    {
        return ($this->block[1]==73 && //I
                $this->block[2]==68 && //D
                $this->block[3]==51);  //3
    }
    protected function startswithpk()
    {
        return ($this->block[1]==80 && //P
                $this->block[2]==75);  //K
    }
    protected function containsvbrxing()
    {
        //echo "<!--".$this->block[37]." ".$this->block[38]."-->";
        //echo "<!--".$this->block[39]." ".$this->block[40]."-->";
        return(
               ($this->block[37]==88  && //X 0x58
                $this->block[38]==105 && //i 0x69
                $this->block[39]==110 && //n 0x6E
                $this->block[40]==103)   //g 0x67
/*               || 
               ($this->block[21]==88  && //X 0x58
                $this->block[22]==105 && //i 0x69
                $this->block[23]==110 && //n 0x6E
                $this->block[24]==103)   //g 0x67*/
              );   
    } 
    protected function debugbytes()
    {
        for($j=0; $j<10; $j++)
        {
            for($i=0; $i<8; $i++)
            {
                if ($i==4) echo " ";
                echo $this->getnextbit();
            }
            echo "<BR>";
        }
    }
    protected function prefetchblock()
    {
        $block = fread($this->fd, $this->blockmax);
        $this->blocksize = strlen($block);
        $this->block = unpack("C*", $block);
        $this->blockpos=0;
    }
    protected function skipid3tag()
    {
        $bits=$this->getnextbits(24);//ID3
        $bits.=$this->getnextbits(24);//v.v flags
        //3 bytes 1 version byte 2 byte flags
        $arr = array();
        $arr[&#39;ID3v2 Major version&#39;] = bindec(substr($bits,24,8));
        $arr[&#39;ID3v2 Minor version&#39;] = bindec(substr($bits,32,8));
        $arr[&#39;ID3v2 flags&#39;        ] = bindec(substr($bits,40,8));
        if (substr($bits,40,1)) $arr[&#39;Unsynchronisation&#39;]=true;
        if (substr($bits,41,1)) $arr[&#39;Extended header&#39;]=true;
        if (substr($bits,42,1)) $arr[&#39;Experimental indicator&#39;]=true;
        if (substr($bits,43,1)) $arr[&#39;Footer present&#39;]=true;
        $size = "";
        for($i=0; $i<4; $i++)
        {
            $this->getnextbit();//skip this bit, should be 0
            $size.= $this->getnextbits(7);
        }
        $arr[&#39;ID3v2 Tags Size&#39;]=bindec($size);//now the size is in bytes;
        if ($arr[&#39;ID3v2 Tags Size&#39;] - $this->blockmax>0)
        {
            fseek($this->fd, $arr[&#39;ID3v2 Tags Size&#39;]+10 );
            $this->prefetchblock();
            if (isset($arr[&#39;Footer present&#39;]) && $arr[&#39;Footer present&#39;])
            {
                for($i=0; $i<10; $i++)
                    $this->getnextbyte();//10 footer bytes
            }
        }
        else
        {
            for($i=0; $i<$arr[&#39;ID3v2 Tags Size&#39;]; $i++)
                $this->getnextbyte();
        }
    }
    protected function getnextbit()
    {
        if ($this->bitpos==8)
            return false;
        $b=0;
        $whichbit = 7-$this->bitpos;
        $mult = $this->powarr[$whichbit]; //$mult = pow(2,7-$this->pos);
        $b = $this->block[$this->blockpos+1] & $mult;
        $b = $b >> $whichbit;
        $this->bitpos++;
        if ($this->bitpos==8)
        {
            $this->blockpos++;
                
            if ($this->blockpos==$this->blockmax) //end of block reached
            {
                $this->prefetchblock();
            }
            else if ($this->blockpos==$this->blocksize) 
            {//end of short block reached (shorter than blockmax)
                return;//eof 
            }
            
            $this->bitpos=0;
        }
        return $b;
    }
    protected function getnextbits($n=1)
    {
        $b="";
        for($i=0; $i<$n; $i++)
            $b.=$this->getnextbit();
        return $b;
    }
    protected function getnextbyte()
    {
        if ($this->blockpos>=$this->blocksize)
            return;
        $this->bitpos=0;
        $b=$this->block[$this->blockpos+1];
        $this->blockpos++;
        return $b;
    }
    //-----------------------------------------------------------------------------
    public static function is_layer1(&$mp3) { return ($mp3[&#39;Layer Description&#39;]==&#39;11&#39;); }
    public static function is_layer2(&$mp3) { return ($mp3[&#39;Layer Description&#39;]==&#39;10&#39;); }
    public static function is_layer3(&$mp3) { return ($mp3[&#39;Layer Description&#39;]==&#39;01&#39;); }
    public static function is_mpeg10(&$mp3)  { return ($mp3[&#39;MPEG version&#39;]==&#39;11&#39;); }
    public static function is_mpeg20(&$mp3)  { return ($mp3[&#39;MPEG version&#39;]==&#39;10&#39;); }
    public static function is_mpeg25(&$mp3)  { return ($mp3[&#39;MPEG version&#39;]==&#39;00&#39;); }
    public static function is_mpeg20or25(&$mp3)  { return ($mp3[&#39;MPEG version&#39;]{1}==&#39;0&#39;); }
    //-----------------------------------------------------------------------------
    public static function bitratelookup(&$mp3)
    {
        //bits               V1,L1  V1,L2  V1,L3  V2,L1  V2,L2&L3
        $array = array();
        $array[&#39;0000&#39;]=array(&#39;free&#39;,&#39;free&#39;,&#39;free&#39;,&#39;free&#39;,&#39;free&#39;);
        $array[&#39;0001&#39;]=array(  &#39;32&#39;,  &#39;32&#39;,  &#39;32&#39;,  &#39;32&#39;,   &#39;8&#39;);
        $array[&#39;0010&#39;]=array(  &#39;64&#39;,  &#39;48&#39;,  &#39;40&#39;,  &#39;48&#39;,  &#39;16&#39;);
        $array[&#39;0011&#39;]=array(  &#39;96&#39;,  &#39;56&#39;,  &#39;48&#39;,  &#39;56&#39;,  &#39;24&#39;);
        $array[&#39;0100&#39;]=array( &#39;128&#39;,  &#39;64&#39;,  &#39;56&#39;,  &#39;64&#39;,  &#39;32&#39;);
        $array[&#39;0101&#39;]=array( &#39;160&#39;,  &#39;80&#39;,  &#39;64&#39;,  &#39;80&#39;,  &#39;40&#39;);
        $array[&#39;0110&#39;]=array( &#39;192&#39;,  &#39;96&#39;,  &#39;80&#39;,  &#39;96&#39;,  &#39;48&#39;);
        $array[&#39;0111&#39;]=array( &#39;224&#39;, &#39;112&#39;,  &#39;96&#39;, &#39;112&#39;,  &#39;56&#39;);
        $array[&#39;1000&#39;]=array( &#39;256&#39;, &#39;128&#39;, &#39;112&#39;, &#39;128&#39;,  &#39;64&#39;);
        $array[&#39;1001&#39;]=array( &#39;288&#39;, &#39;160&#39;, &#39;128&#39;, &#39;144&#39;,  &#39;80&#39;);
        $array[&#39;1010&#39;]=array( &#39;320&#39;, &#39;192&#39;, &#39;160&#39;, &#39;160&#39;,  &#39;96&#39;);
        $array[&#39;1011&#39;]=array( &#39;352&#39;, &#39;224&#39;, &#39;192&#39;, &#39;176&#39;, &#39;112&#39;);
        $array[&#39;1100&#39;]=array( &#39;384&#39;, &#39;256&#39;, &#39;224&#39;, &#39;192&#39;, &#39;128&#39;);
        $array[&#39;1101&#39;]=array( &#39;416&#39;, &#39;320&#39;, &#39;256&#39;, &#39;224&#39;, &#39;144&#39;);
        $array[&#39;1110&#39;]=array( &#39;448&#39;, &#39;384&#39;, &#39;320&#39;, &#39;256&#39;, &#39;160&#39;);
        $array[&#39;1111&#39;]=array( &#39;bad&#39;, &#39;bad&#39;, &#39;bad&#39;, &#39;bad&#39;, &#39;bad&#39;);
        
        $whichcolumn=-1;
        if      (mp3file::is_mpeg10($mp3) && mp3file::is_layer1($mp3) )//V1,L1
            $whichcolumn=0;
        else if (mp3file::is_mpeg10($mp3) && mp3file::is_layer2($mp3) )//V1,L2
            $whichcolumn=1;
        else if (mp3file::is_mpeg10($mp3) && mp3file::is_layer3($mp3) )//V1,L3
            $whichcolumn=2;
        else if (mp3file::is_mpeg20or25($mp3) && mp3file::is_layer1($mp3) )//V2,L1
            $whichcolumn=3;
        else if (mp3file::is_mpeg20or25($mp3) && (mp3file::is_layer2($mp3) || mp3file::is_layer3($mp3)) )
            $whichcolumn=4;//V2,   L2||L3 
        
        if (isset($array[$mp3[&#39;Bitrate Index&#39;]][$whichcolumn]))
            return $array[$mp3[&#39;Bitrate Index&#39;]][$whichcolumn];
        else 
            return "bad";
    }
    //-----------------------------------------------------------------------------
    public static function samplelookup(&$mp3)
    {
        //bits               MPEG1   MPEG2   MPEG2.5
        $array = array();
        $array[&#39;00&#39;] =array(&#39;44100&#39;,&#39;22050&#39;,&#39;11025&#39;);
        $array[&#39;01&#39;] =array(&#39;48000&#39;,&#39;24000&#39;,&#39;12000&#39;);
        $array[&#39;10&#39;] =array(&#39;32000&#39;,&#39;16000&#39;,&#39;8000&#39;);
        $array[&#39;11&#39;] =array(&#39;res&#39;,&#39;res&#39;,&#39;res&#39;);
        
        $whichcolumn=-1;
        if      (mp3file::is_mpeg10($mp3))
            $whichcolumn=0;
        else if (mp3file::is_mpeg20($mp3))
            $whichcolumn=1;
        else if (mp3file::is_mpeg25($mp3))
            $whichcolumn=2;
        
        if (isset($array[$mp3[&#39;Sampling Freq Idx&#39;]][$whichcolumn]))
            return $array[$mp3[&#39;Sampling Freq Idx&#39;]][$whichcolumn];
        else 
            return &#39;unknown&#39;;
    }
    //-----------------------------------------------------------------------------
    public static function getframesize(&$mp3)
    {
        if ($mp3[&#39;Sampling Rate&#39;]>0)
        {
            return  ceil((144 * $mp3[&#39;Bitrate&#39;]*1000)/$mp3[&#39;Sampling Rate&#39;]) + $mp3[&#39;Padding Bit&#39;];
        }
        return &#39;unknown&#39;;
    }
    //-----------------------------------------------------------------------------
    public static function getduration(&$mp3,$startat)
    {
        if ($mp3[&#39;Bitrate&#39;]>0)
        {
            $KBps = ($mp3[&#39;Bitrate&#39;]*1000)/8;
            $datasize = ($mp3[&#39;Filesize&#39;] - ($startat/8));
            $length = $datasize / $KBps;
            return sprintf("%d", $length);
        }
        return "unknown";
    }
    //-----------------------------------------------------------------------------
    public static function seconds_to_mmss($duration)
    {
        return sprintf("%d:%02d", ($duration /60), $duration %60 );
    }
}

呼び出し

<?php
include_once &#39;mp3file.class.php&#39;;
function mp3Time($file) {
   $m = new mp3file($file);
   $a = $m->get_metadata();
   return $a[&#39;Length mm:ss&#39;] ? $a[&#39;Length mm:ss&#39;] : 0;
}
function mp3Info($file) {
   $m = new mp3file($file);
   return $m->get_metadata();
}
$_time = mp3Time(&#39;Beyond-情人.mp3&#39;);
echo "歌曲时间长：{$_time}\n";
$_info = mp3Info(&#39;Beyond-情人.mp3&#39;);
print_r($_info);

出力情報

→ php mp3.php
歌曲时间长：5:15
Array
(
    [Filesize] => 7576152
    [Encoding] => CBR
    [MPEG version] => 11
    [Layer Description] => 01
    [Protection Bit] => 1
    [Bitrate Index] => 1011
    [Sampling Freq Idx] => 00
    [Padding Bit] => 0
    [Private Bit] => 0
    [Channel Mode] => 00
    [Mode Extension] => 00
    [Copyright] => 0
    [Original Media] => 1
    [Emphasis] => 0
    [Bitrate] => 192
    [Sampling Rate] => 44100
    [Frame Size] => 627
    [Length] => 315
    [Length mm:ss] => 5:15
)

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