很早之前在网上看到一个获取 MP3 音频信息的 php 类。如：播放时长、文件大小、文件编码等等
<?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();
$this->mp3data['Filesize'] = filesize($filename);
$this->fd = fopen($filename,'rb');
$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['Encoding'] = 'VBR';
$iscbrmp3=false;
}
else if ($this->startswithpk())
{
$this->mp3data['Encoding'] = 'Unknown';
$iscbrmp3=false;
}
if ($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['Encoding' ] = 'CBR';
$this->mp3data['MPEG version' ] = $this->getnextbits(2);
$this->mp3data['Layer Description'] = $this->getnextbits(2);
$this->mp3data['Protection Bit' ] = $this->getnextbits(1);
$this->mp3data['Bitrate Index' ] = $this->getnextbits(4);
$this->mp3data['Sampling Freq Idx'] = $this->getnextbits(2);
$this->mp3data['Padding Bit' ] = $this->getnextbits(1);
$this->mp3data['Private Bit' ] = $this->getnextbits(1);
$this->mp3data['Channel Mode' ] = $this->getnextbits(2);
$this->mp3data['Mode Extension' ] = $this->getnextbits(2);
$this->mp3data['Copyright' ] = $this->getnextbits(1);
$this->mp3data['Original Media' ] = $this->getnextbits(1);
$this->mp3data['Emphasis' ] = $this->getnextbits(1);
$this->mp3data['Bitrate' ] = mp3file::bitratelookup($this->mp3data);
$this->mp3data['Sampling Rate' ] = mp3file::samplelookup($this->mp3data);
$this->mp3data['Frame Size' ] = mp3file::getframesize($this->mp3data);
$this->mp3data['Length' ] = mp3file::getduration($this->mp3data,$this->tell2());
$this->mp3data['Length mm:ss' ] = mp3file::seconds_to_mmss($this->mp3data['Length']);
if ($this->mp3data['Bitrate' ]=='bad' ||
$this->mp3data['Bitrate' ]=='free' ||
$this->mp3data['Sampling Rate']=='unknown' ||
$this->mp3data['Frame Size' ]=='unknown' ||
$this->mp3data['Length' ]=='unknown')
$this->mp3data = array('Filesize'=>$this->mp3data['Filesize'], 'Encoding'=>'Unknown');
}
else
{
if(!isset($this->mp3data['Encoding']))
$this->mp3data['Encoding'] = 'Unknown';
}
}
protected function tell()
{
return ftell($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();
$arr['ID3v2 Major version'] = bindec(substr($bits,24,8));
$arr['ID3v2 Minor version'] = bindec(substr($bits,32,8));
$arr['ID3v2 flags' ] = bindec(substr($bits,40,8));
if (substr($bits,40,1)) $arr['Unsynchronisation']=true;
if (substr($bits,41,1)) $arr['Extended header']=true;
if (substr($bits,42,1)) $arr['Experimental indicator']=true;
if (substr($bits,43,1)) $arr['Footer present']=true;
$size = "";
for($i=0; $i<4; $i++)
{
$this->getnextbit();//skip this bit, should be 0
$size.= $this->getnextbits(7);
}
$arr['ID3v2 Tags Size']=bindec($size);//now the size is in bytes;
if ($arr['ID3v2 Tags Size'] - $this->blockmax>0)
{
fseek($this->fd, $arr['ID3v2 Tags Size']+10 );
$this->prefetchblock();
if (isset($arr['Footer present']) && $arr['Footer present'])
{
for($i=0; $i<10; $i++)
$this->getnextbyte();//10 footer bytes
}
}
else
{
for($i=0; $i<$arr['ID3v2 Tags Size']; $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 ($mp3['Layer Description']=='11'); }
public static function is_layer2(&$mp3) { return ($mp3['Layer Description']=='10'); }
public static function is_layer3(&$mp3) { return ($mp3['Layer Description']=='01'); }
public static function is_mpeg10(&$mp3) { return ($mp3['MPEG version']=='11'); }
public static function is_mpeg20(&$mp3) { return ($mp3['MPEG version']=='10'); }
public static function is_mpeg25(&$mp3) { return ($mp3['MPEG version']=='00'); }
public static function is_mpeg20or25(&$mp3) { return ($mp3['MPEG version']{1}=='0'); }
//-----------------------------------------------------------------------------
public static function bitratelookup(&$mp3)
{
//bits V1,L1 V1,L2 V1,L3 V2,L1 V2,L2&L3
$array = array();
$array['0000']=array('free','free','free','free','free');
$array['0001']=array( '32', '32', '32', '32', '8');
$array['0010']=array( '64', '48', '40', '48', '16');
$array['0011']=array( '96', '56', '48', '56', '24');
$array['0100']=array( '128', '64', '56', '64', '32');
$array['0101']=array( '160', '80', '64', '80', '40');
$array['0110']=array( '192', '96', '80', '96', '48');
$array['0111']=array( '224', '112', '96', '112', '56');
$array['1000']=array( '256', '128', '112', '128', '64');
$array['1001']=array( '288', '160', '128', '144', '80');
$array['1010']=array( '320', '192', '160', '160', '96');
$array['1011']=array( '352', '224', '192', '176', '112');
$array['1100']=array( '384', '256', '224', '192', '128');
$array['1101']=array( '416', '320', '256', '224', '144');
$array['1110']=array( '448', '384', '320', '256', '160');
$array['1111']=array( 'bad', 'bad', 'bad', 'bad', 'bad');
$whichcolumn=-1;
if (mp3file::is_mpeg10($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[$mp3['Bitrate Index']][$whichcolumn]))
return $array[$mp3['Bitrate Index']][$whichcolumn];
else
return "bad";
}
//-----------------------------------------------------------------------------
public static function samplelookup(&$mp3)
{
//bits MPEG1 MPEG2 MPEG2.5
$array = array();
$array['00'] =array('44100','22050','11025');
$array['01'] =array('48000','24000','12000');
$array['10'] =array('32000','16000','8000');
$array['11'] =array('res','res','res');
$whichcolumn=-1;
if (mp3file::is_mpeg10($mp3))
$whichcolumn=0;
else if (mp3file::is_mpeg20($mp3))
$whichcolumn=1;
else if (mp3file::is_mpeg25($mp3))
$whichcolumn=2;
if (isset($array[$mp3['Sampling Freq Idx']][$whichcolumn]))
return $array[$mp3['Sampling Freq Idx']][$whichcolumn];
else
return 'unknown';
}
//-----------------------------------------------------------------------------
public static function getframesize(&$mp3)
{
if ($mp3['Sampling Rate']>0)
{
return ceil((144 * $mp3['Bitrate']*1000)/$mp3['Sampling Rate']) + $mp3['Padding Bit'];
}
return 'unknown';
}
//-----------------------------------------------------------------------------
public static function getduration(&$mp3,$startat)
{
if ($mp3['Bitrate']>0)
{
$KBps = ($mp3['Bitrate']*1000)/8;
$datasize = ($mp3['Filesize'] - ($startat/8));
$length = $datasize / $KBps;
return sprintf("%d", $length);
}
return "unknown";
}
//-----------------------------------------------------------------------------
public static function seconds_to_mmss($duration)
{
return sprintf("%d:%02d", ($duration /60), $duration %60 );
}
}
调用
<?php
include_once 'mp3file.class.php';
function mp3Time($file) {
$m = new mp3file($file);
$a = $m->get_metadata();
return $a['Length mm:ss'] ? $a['Length mm:ss'] : 0;
}
function mp3Info($file) {
$m = new mp3file($file);
return $m->get_metadata();
}
$_time = mp3Time('Beyond-情人.mp3');
echo "歌曲时间长：{$_time}\n";
$_info = mp3Info('Beyond-情人.mp3');
print_r($_info);
输出信息
→ 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
)
