這幾天突發奇想，想做一個應用關於合並搞笑音頻的。但是php畢竟是web腳本文件，在處理這種二進制音頻的能力上有所欠缺，在國內的網站上並沒有找到完整的解決方案，但在國外一個牛B人物的博客上發現相關的解決方案。
這是一個MP3的類，下面我會講述如何使用這個類。
<?php
class mp3
{
var $str;
var $time;
var $frames;
function mp3($path=””)
{
if($path!=””)
{
$this->str = file_get_contents($path);
}
}
function setStr($str)
{
$this->str = $str;
}
function setFileInfoExact()
{
$maxStrLen = strlen($this->str);
$currentStrPos = strpos($this->str,chr(255));
$framesCount=0;
$time = 0;
while($currentStrPos < $maxStrLen)
{
$str = substr($this->str,$currentStrPos,4);
$strlen = strlen($str);
$parts = array();
for($i=0;$i < $strlen;$i++)
{
$parts[] = $this->decbinFill(ord($str[$i]),8);
}
if($parts[0] != “11111111”)
{
if(($maxStrLen-128) > $currentStrPos)
{
return false;
}
else
{
$this->time = $time;
$this->frames = $framesCount;
return true;
}
}
$a = $this->doFrameStuff($parts);
$currentStrPos += $a[0];
$time += $a[1];
$framesCount++;
}
$this->time = $time;
$this->frames = $framesCount;
return true;
}
function extract($start,$length)
{
$maxStrLen = strlen($this->str);
$currentStrPos = strpos($this->str,chr(255));
$framesCount=0;
$time = 0;
$startCount = -1;
$endCount = -1;
while($currentStrPos < $maxStrLen)
{
if($startCount==-1&&$time>=$start)
{
$startCount = $currentStrPos;
}
if($endCount==-1&&$time>=($start+$length))
{
$endCount = $currentStrPos-$startCount;
}
$doFrame = true;
$str = substr($this->str,$currentStrPos,4);
$strlen = strlen($str);
$parts = array();
for($i=0;$i < $strlen;$i++)
{
$parts[] = $this->decbinFill(ord($str[$i]),8);
}
if($parts[0] != “11111111”)
{
if(($maxStrLen-128) > $currentStrPos)
{
$doFrame = false;
}
else
{
$doFrame = false;
}
}
if($doFrame)
{
$a = $this->doFrameStuff($parts);
$currentStrPos += $a[0];
$time += $a[1];
$framesCount++;
}
}
$mp3 = new mp3();
if($endCount == -1)
{
$endCount = $maxStrLen-$startCount;
}
if($startCount!=-1&&$endCount!=-1)
{
$mp3->setStr(substr($this->str,$startCount,$endCount));
}
return $mp3;
}
function decbinFill($dec,$length=0)
{
$str = decbin($dec);
$nulls = $length-strlen($str);
if($nulls>0)
{
for($i=0;$i<$nulls;$i++)
{
$str = ‘0’.$str;
}
}
return $str;
}
function doFrameStuff($parts)
{
//Get Audio Version
$errors = array();
switch(substr($parts[1],3,2))
{
case ’01′:
$errors[]=’Reserved audio version';
break;
case ’00′:
$audio = 2.5;
break;
case ’10′:
$audio = 2;
break;
case ’11′:
$audio = 1;
break;
}
//Get Layer
switch(substr($parts[1],5,2))
{
case ’01′:
$layer = 3;
break;
case ’00′:
$errors[]=’Reserved layer';
break;
case ’10′:
$layer = 2;
break;
case ’11′:
$layer = 1;
break;
}
//Get Bitrate
$bitFlag = substr($parts[2],0,4);
$bitArray = array(
‘0000’ => array(free, free, free, free, free),
‘0001’ => array(32, 32, 32, 32, 8),
‘0010’ => array(64, 48, 40, 48, 16),
‘0011’ => array(96, 56, 48, 56, 24),
‘0100’ => array(128, 64, 56, 64, 32),
‘0101’ => array(160, 80, 64, 80, 40),
‘0110’ => array(192, 96, 80, 96, 48),
‘0111’ => array(224, 112, 96, 112, 56),
‘1000’ => array(256, 128, 112, 128, 64),
‘1001’ => array(288, 160, 128, 144, 80),
‘1010’ => array(320, 192, 160, 160, 96),
‘1011’ => array(352, 224, 192, 176, 112),
‘1100’ => array(384, 256, 224, 192, 128),
‘1101’ => array(416, 320, 256, 224, 144),
‘1110’ => array(448, 384, 320, 256, 160),
‘1111’ => array(bad, bad, bad, bad, bad)
);
$bitPart = $bitArray[$bitFlag];
$bitArrayNumber;
if($audio==1)
{
switch($layer)
{
case 1:
$bitArrayNumber=0;
break;
case 2:
$bitArrayNumber=1;
break;
case 3:
$bitArrayNumber=2;
break;
}
}
else
{
switch($layer)
{
case 1:
$bitArrayNumber=3;
break;
case 2:
$bitArrayNumber=4;
break;
case 3:
$bitArrayNumber=4;
break;
}
}
$bitRate = $bitPart[$bitArrayNumber];
//Get Frequency
$frequencies = array(
1=>array(’00’=>44100,
’01’=>48000,
’10’=>32000,
’11’=>’reserved’),
2=>array(),
2.5=>array());
$freq = $frequencies[$audio][substr($parts[2],4,2)];
//IsPadded?
$padding = substr($parts[2],6,1);
if($layer==3||$layer==2)
{
//FrameLengthInBytes = 144 * BitRate / SampleRate + Padding
$frameLength = 144 * $bitRate * 1000 / $freq + $padding;
}
$frameLength = floor($frameLength);
$seconds += $frameLength*8/($bitRate*1000);
return array($frameLength,$seconds);
//Calculate next when next frame starts.
//Capture next frame.
}
function setIdv3_2($track,$title,$artist,$album,$year,$genre,$comments,$composer,$origArtist,
$copyright,$url,$encodedBy)
{
$urlLength = (int)(strlen($url)+2);
$copyrightLength = (int)(strlen($copyright)+1);
$origArtistLength = (int)(strlen($origArtist)+1);
$composerLength = (int)(strlen($composer)+1);
$commentsLength = (int)strlen($comments)+5;
$titleLength = (int) strlen($title)+1;
$artistLength = (int)strlen($artist)+1;
$albumLength = (int) strlen($album)+1;
$genreLength = (int) strlen($genre)+1;
$encodedByLength = (int)(strlen($encodedBy)+1);
$trackLength = (int) strlen($track) + 1;
$yearLength = (int) strlen($year)+1;
$str .= chr(73);//I
$str .= chr(68);//D
$str .= chr(51);//3
$str .= chr(3);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(8);//
$str .= chr(53);//5
$str .= chr(84);//T
$str .= chr(82);//R
$str .= chr(67);//C
$str .= chr(75);//K
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr($trackLength);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= $track;
$str .= chr(84);//T
$str .= chr(69);//E
$str .= chr(78);//N
$str .= chr(67);//C
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr($encodedByLength);//
$str .= chr(64);//@
$str .= chr(0);//
$str .= chr(0);//
$str .= $encodedBy;
$str .= chr(87);//W
$str .= chr(88);//X
$str .= chr(88);//X
$str .= chr(88);//X
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr($urlLength);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= $url;
$str .= chr(84);//T
$str .= chr(67);//C
$str .= chr(79);//O
$str .= chr(80);//P
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr($copyrightLength);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= $copyright;
$str .= chr(84);//T
$str .= chr(79);//O
$str .= chr(80);//P
$str .= chr(69);//E
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr($origArtistLength);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= $origArtist;
$str .= chr(84);//T
$str .= chr(67);//C
$str .= chr(79);//O
$str .= chr(77);//M
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr($composerLength);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= $composer;
$str .= chr(67);//C
$str .= chr(79);//O
$str .= chr(77);//M
$str .= chr(77);//M
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr($commentsLength);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(9);//
$str .= chr(0);//
$str .= chr(0);//
$str .= $comments;
$str .= chr(84);//T
$str .= chr(67);//C
$str .= chr(79);//O
$str .= chr(78);//N
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr($genreLength);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= $genre;
$str .= chr(84);//T
$str .= chr(89);//Y
$str .= chr(69);//E
$str .= chr(82);//R
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr($yearLength);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= $year;
$str .= chr(84);//T
$str .= chr(65);//A
$str .= chr(76);//L
$str .= chr(66);//B
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr($albumLength);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= $album;
$str .= chr(84);//T
$str .= chr(80);//P
$str .= chr(69);//E
$str .= chr(49);//1
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr($artistLength);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= $artist;
$str .= chr(84);//T
$str .= chr(73);//I
$str .= chr(84);//T
$str .= chr(50);//2
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr($titleLength);//
$str .= chr(0);//
$str .= chr(0);//
$str .= chr(0);//
$str .= $title;
$this->str = $str.$this->str;
}
function mergeBehind(mp3 $mp3)
{
$this->str .= $mp3->str;
}
function mergeInfront(mp3 $mp3)
{
$this->str = $mp3->str.$this->str;
