解析用PHP读写音频文件信息的详解(支持WMA和MP3)
author：一佰互联 2019-04-30 click：158
复制代码 代码如下:
<?php
// AudioExif.class.php
// 用PHP进行音频文件头部信息的读取与写入
// 目前只支持 WMA 和 MP3 两种格式, 只支持常用的几个头部信息
//
// 写入信息支持: Title(名称), Artist(艺术家), Copyright(版权), Description (描述)
// Year(年代), Genre (流派), AlbumTitle (专辑标题)
// 其中 mp3 和 wma 略有不同, 具体返回的信息还可能更多, 但只有以上信息可以被写入
// mp3 还支持 Track (曲目编号写入)
// 对于 MP3 文件支持 ID3v1也支持ID3v2, 读取时优先 v2, 写入时总是会写入v1, 必要时写入v2
//
// 用法说明: (由于 wma 使用 Unicode 存取, 故还需要 mb_convert_encoding() 扩展
// 返回数据及写入数据均为 ANSI 编码, 即存什么就显示什么 (中文_GB2312)
//
// require ("AudioExif.class.php");
// $AE = new AudioExif;
// $file = "/path/to/test.mp3";
//
// 1. 检查文件是否完整 (only for wma, mp3始终返回 true)
//
// $AE->CheckSize($file);
//
// 2. 读取信息, 返回值由信息组成的数组, 键名解释参见上方
//
// print_r($AE->GetInfo($file));
//
// 3. 写入信息, 第二参数是一个哈希数组, 键->值, 支持的参见上方的, mp3也支持 Track
// 要求第一参数的文件路径可由本程序写入
// $pa = array("Title" => "新标题", "AlbumTitle" => "新的专辑名称");
// $AE->SetInfo($file, $pa);
//
//
// 其它: 该插件花了不少时间搜集查找 wma及mp3 的文件格式说明文档与网页, 希望对大家有用.
// 其实网上已经有不少类似的程序, 但对 wma 实在太少了, 只能在 win 平台下通过 M$ 的
// API 来操作, 而 MP3 也很少有可以在 unix/linux 命令行操作的, 所以特意写了这个模块
//
// 如果发现 bug 或提交 patch, 或加以改进使它更加健壮, 请告诉我.
// (关于 ID3和Wma的文件格式及结构 在网上应该都可以找到参考资料)
//
if (!extension_loaded("mbstring"))
{
trigger_error("PHP Extension module `mbstring` is required for AudioExif", E_USER_WARNING);
return true;
}
// the Main Class
class AudioExif
{
// public vars
var $_wma = false;
var $_mp3 = false;
// Construct
function AudioExif()
{
// nothing to do
}
// check the filesize
function CheckSize($file)
{
$handler = &$this->_get_handler($file);
if (!$handler) return false;
return $handler->check_size($file);
}
// get the infomations
function GetInfo($file)
{
$handler = &$this->_get_handler($file);
if (!$handler) return false;
return $handler->get_info($file);
}
// write the infomations
function SetInfo($file, $pa)
{
if (!is_writable($file))
{
trigger_error("AudioExif: file `" . $file . "` can not been overwritten", E_USER_WARNING);
return false;
}
$handler = &$this->_get_handler($file);
if (!$handler) return false;
return $handler->set_info($file, $pa);
}
// private methods
function &_get_handler($file)
{
$ext = strtolower(strrchr($file, "."));
$ret = false;
if ($ext == ".mp3")
{ // MP3
$ret = &$this->_mp3;
if (!$ret) $ret = new _Mp3Exif();
}
else if ($ext == ".wma")
{ // wma
$ret = &$this->_wma;
if (!$ret) $ret = new _WmaExif();
}
else
{ // unknown
trigger_error("AudioExif not supported `" . $ext . "` file.", E_USER_WARNING);
}
return $ret;
}
}
// DBCS => gb2312
function dbcs_gbk($str)
{
// strip the last ""
$str = substr($str, 0, -2);
return mb_convert_encoding($str, "GBK", "UCS-2LE");
}
// gb2312 => DBCS
function gbk_dbcs($str)
{
$str = mb_convert_encoding($str, "UCS-2LE", "GBK");
$str .= "";
return $str;
}
// file exif
class _AudioExif
{
var $fd;
var $head;
var $head_off;
var $head_buf; // init the file handler
function _file_init($fpath, $write = false)
{
$mode = ($write ? "rb+" : "rb");
$this->fd = @fopen($fpath, $mode);
if (!$this->fd)
{
trigger_error("AudioExif: `" . $fpath . "` can not be opened with mode `" . $mode . "`", E_USER_WARNING);
return false;
}
$this->head = false;
$this->head_off = 0;
$this->head_buf = "";
return true;
}
// read buffer from the head_buf & move the off pointer
function _read_head_buf($len)
{
if ($len <= 0) return NULL;
$buf = substr($this->head_buf, $this->head_off, $len);
$this->head_off += strlen($buf);
return $buf;
}
// read one short value
function _read_head_short()
{
$ord1 = ord(substr($this->head_buf, $this->head_off, 1));
$ord2 = ord(substr($this->head_buf, $this->head_off+1, 1));
$this->head_off += 2;
return ($ord1 + ($ord2<<8));
}
// save the file head
function _file_save($head, $olen, $nlen = 0)
{
if ($nlen == 0) $nlen = strlen($head);
if ($nlen == $olen)
{
// shorter
flock($this->fd, LOCK_EX);
fseek($this->fd, 0, SEEK_SET);
fwrite($this->fd, $head, $nlen);
flock($this->fd, LOCK_UN);
}
else
{
// longer, buffer required
$stat = fstat($this->fd);
$fsize = $stat["size"];
// buf required (4096?) 应该不会 nlen - olen > 4096 吧
$woff = 0;
$roff = $olen;
// read first buffer
flock($this->fd, LOCK_EX);
fseek($this->fd, $roff, SEEK_SET);
$buf = fread($this->fd, 4096);
// seek to start
fseek($this->fd, $woff, SEEK_SET);
fwrite($this->fd, $head, $nlen);
$woff += $nlen;
// seek to woff & write the data
do
{
$buf2 = $buf;
$roff += 4096;
if ($roff < $fsize)
{
fseek($this->fd, $roff, SEEK_SET);
$buf = fread($this->fd, 4096);
}
// save last buffer
$len2 = strlen($buf2);
fseek($this->fd, $woff, SEEK_SET);
fwrite($this->fd, $buf2, $len2);
$woff += $len2;
}
while ($roff < $fsize);
ftruncate($this->fd, $woff);
flock($this->fd, LOCK_UN);
}
}
// close the file
function _file_deinit()
{
if ($this->fd)
{
fclose($this->fd);
$this->fd = false;
}
}
}
// wma class
class _WmaExif extends _AudioExif
{
var $items1 = array("Title", "Artist", "Copyright", "Description", "Reserved");
var $items2 = array("Year", "Genre", "AlbumTitle");
// check file size (length) maybe invalid file
function check_size($file)
{
$ret = false;
if (!$this->_file_init($file)) return true;
if ($this->_init_header())
{
$buf = fread($this->fd, 24);
$tmp = unpack("H32id/Vlen/H8unused", $buf);
if ($tmp["id"] == "3626b2758e66cf11a6d900aa0062ce6c")
{
$stat = fstat($this->fd);
$ret = ($stat["size"] == ($this->head["len"] + $tmp["len"]));
}
}
$this->_file_deinit();
return $ret;
}
// set info (save the infos)
function set_info($file, $pa)
{
// check the pa
settype($pa, "array");
if (!$this->_file_init($file, true)) return false;
if (!$this->_init_header())
{
$this->_file_deinit();
return false;
} // parse the old header & generate the new header
$head_body = "";
$st_found = $ex_found = false;
$head_num = $this->head["num"];
while (($tmp = $this->_get_head_frame()) && ($head_num > 0))
{
$head_num--;
if ($tmp["id"] == "3326b2758e66cf11a6d900aa0062ce6c")
{ // Standard Info
// 1-4
$st_found = true;
$st_body1 = $st_body2 = "";
$lenx = unpack("v5", $this->_read_head_buf(10));
$tmp["len"] -= 34; // 10 + 24
for ($i = 0; $i < count($this->items1); $i++)
{
$l = $lenx[$i+1];
$k = $this->items1[$i];
$tmp["len"] -= $l;
$data = $this->_read_head_buf($l);
if (isset($pa[$k])) $data = gbk_dbcs($pa[$k]);
$st_body2 .= $data;
$st_body1 .= pack("v", strlen($data));
}
// left length
if ($tmp["len"] > 0) $st_body2 .= $this->_read_head_buf($tmp["len"]);
// save to head_body
$head_body .= pack("H32VH8", $tmp["id"], strlen($st_body1 . $st_body2)+24, $tmp["unused"]);
$head_body .= $st_body1 . $st_body2;
}
else if ($tmp["id"] == "40a4d0d207e3d21197f000a0c95ea850")
{ // extended info
$ex_found = true; $inum = $this->_read_head_short();
$inum2 = $inum;
$tmp["len"] -= 26; // 24 + 2
$et_body = "";
while ($tmp["len"] > 0 && $inum > 0)
{
// attribute name
$nlen = $this->_read_head_short();
$nbuf = $this->_read_head_buf($nlen);
// the flag & value length
$flag = $this->_read_head_short();
$vlen = $this->_read_head_short();
$vbuf = $this->_read_head_buf($vlen);
// set the length
$tmp["len"] -= (6 + $nlen + $vlen);
$inum--;
// save the data?
$name = dbcs_gbk($nbuf);
$k = substr($name, 3);
if (in_array($k, $this->items2) && isset($pa[$k]))
{
$vbuf = gbk_dbcs($pa[$k]);
$vlen = strlen($vbuf);
unset($pa[$k]);
}
$et_body .= pack("v", $nlen) . $nbuf . pack("vv", $flag, $vlen) . $vbuf;
}
// new tag insert??
foreach ($this->items2 as $k)
{
if (isset($pa[$k]))
{
$inum2++;
$nbuf = gbk_dbcs("WM/" . $k);
$nlen = strlen($nbuf);
$vbuf = gbk_dbcs($pa[$k]);
$vlen = strlen($vbuf);
$et_body .= pack("v", $nlen) . $nbuf . pack("vv", 0, $vlen) . $vbuf;
}
}
// left buf?
if ($tmp["len"] > 0) $et_body .= $this->_read_head_buf($tmp["len"]);
// save to head_body
$head_body .= pack("H32VH8v", $tmp["id"], strlen($et_body)+26, $tmp["unused"], $inum2);
$head_body .= $et_body;
}
else
{
// just keep other head frame
$head_body .= pack("H32VH8", $tmp["id"], $tmp["len"], $tmp["unused"]);
if ($tmp["len"] > 24) $head_body .= $this->_read_head_buf($tmp["len"]-24);
}
}
// st not found?
if (!$st_found)
{
$st_body1 = $st_body2 = "";
foreach ($this->items1 as $k)
{
$data = (isset($pa[$k]) ? gbk_dbcs($pa[$k]) : "");
$st_body1 .= pack("v", strlen($data));
$st_body2 .= $data;
} // save to head_body
$head_body .= pack("H32Va4", "3326b2758e66cf11a6d900aa0062ce6c", strlen($st_body1 . $st_body2)+24, "");
$head_body .= $st_body1 . $st_body2;
$this->head["num"]++;
}
// ex not found?
if (!$ex_found)
{
$inum = 0;
$et_body = "";
foreach ($this->items2 as $k)
{
$nbuf = gbk_dbcs("WM/" . $k);
$vbuf = (isset($pa[$k]) ? gbk_dbcs($pa[$k]) : "");
$et_body .= pack("v", strlen($nbuf)) . $nbuf . pack("vv", 0, strlen($vbuf)) . $vbuf;
$inum++;
}
$head_body .= pack("H32Va4v", "40a4d0d207e3d21197f000a0c95ea850", strlen($et_body)+26, "", $inum);
$head_body .= $et_body;
$this->head["num"]++;
}
// after save
$new_len = strlen($head_body) + 30;
$old_len = $this->head["len"];
if ($new_len < $old_len)
{
$head_body .= str_repeat("", $old_len - $new_len);
$new_len = $old_len;
}
$tmp = $this->head;
$head_buf = pack("H32VVVH4", $tmp["id"], $new_len, $tmp["len2"], $tmp["num"], $tmp["unused"]);
$head_buf .= $head_body;
$this->_file_save($head_buf, $old_len, $new_len);
// close the file & return
$this->_file_deinit();
return true;
}
// get info
function get_info($file)
{
$ret = array();
if (!$this->_file_init($file)) return false;
if (!$this->_init_header())
{
$this->_file_deinit();
return false;
}
// get the data from head_buf
$head_num = $this->head["num"]; // num of head_frame
while (($tmp = $this->_get_head_frame()) && $head_num > 0)
{
$head_num--;
if ($tmp["id"] == "3326b2758e66cf11a6d900aa0062ce6c")
{ // Standard Info
$lenx = unpack("v*", $this->_read_head_buf(10));
for ($i = 1; $i <= count($this->items1); $i++)
{
$k = $this->items1[$i-1];
$ret[$k] = dbcs_gbk($this->_read_head_buf($lenx[$i]));
}
}
else if ($tmp["id"] == "40a4d0d207e3d21197f000a0c95ea850")
{ // Extended Info
$inum = $this->_read_head_short();
$tmp["len"] -= 26;
while ($inum > 0 && $tmp["len"] > 0)
{
// attribute name
$nlen = $this->_read_head_short();
$nbuf = $this->_read_head_buf($nlen);
// the flag & value length
$flag = $this->_read_head_short();
$vlen = $this->_read_head_short();
$vbuf = $this->_read_head_buf($vlen);
// update the XX
$tmp["len"] -= (6 + $nlen + $vlen);
$inum--;
$name = dbcs_gbk($nbuf);
$k = substr($name, 3);
if (in_array($k, $this->items2))
{ // all is string value (refer to falg for other tags)
$ret[$k] = dbcs_gbk($vbuf);
}
}
}
else
{ // skip only
if ($tmp["len"] > 24) $this->head_off += ($tmp["len"] - 24);
}
}
$this->_file_deinit();
return $ret;
}
// get the header?
function _init_header()
{
fseek($this->fd, 0, SEEK_SET);
$buf = fread($this->fd, 30);
if (strlen($buf) != 30) return false;
$tmp = unpack("H32id/Vlen/Vlen2/Vnum/H4unused", $buf);
if ($tmp["id"] != "3026b2758e66cf11a6d900aa0062ce6c")
return false;
$this->head_buf = fread($this->fd, $tmp["len"] - 30);
$this->head = $tmp;
return true;
}
// _get_head_frame()
function _get_head_frame()
{
$buf = $this->_read_head_buf(24);
if (strlen($buf) != 24) return false;
$tmp = unpack("H32id/Vlen/H8unused", $buf);
return $tmp;
}
}
// mp3 class (if not IDv2 then select IDv1)
class _Mp3Exif extends _AudioExif
{
var $head1;
var $genres = array("Blues","Classic Rock","Country","Dance","Disco","Funk","Grunge","Hip-Hop","Jazz","Metal","New Age","Oldies","Other","Pop","R&B","Rap","Reggae","Rock","Techno","Industrial","Alternative","Ska","Death Metal","Pranks","Soundtrack","Euro-Techno","Ambient","Trip-Hop","Vocal","Jazz+Funk","Fusion","Trance","Classical","Instrumental","Acid","House","Game","Sound Clip","Gospel","Noise","AlternRock","Bass","Soul","Punk","Space","Meditative","Instrumental Pop","Instrumental Rock","Ethnic","Gothic","Darkwave","Techno-Industrial","Electronic","Pop-Folk","Eurodance","Dream","Southern Rock","Comedy","Cult","Gangsta","Top 40","Christian Rap","Pop/Funk","Jungle","Native American","Cabaret","New Wave","Psychadelic","Rave","Showtunes","Trailer","Lo-Fi","Tribal","Acid Punk","Acid Jazz","Polka","Retro","Musical","Rock & Roll","Hard Rock","Unknown");
// MP3 always return true
function check_size($file)
{
return true;
}
// get info
function get_info($file)
{
if (!$this->_file_init($file)) return false;
$ret = false;
if ($this->_init_header())
{
$ret = ($this->head ? $this->_get_v2_info() : $this->_get_v1_info());
$ret["meta"] = $this->_get_meta_info();
}
$this->_file_deinit();
return $ret;
}
// set info
function set_info($file, $pa)
{
if (!$this->_file_init($file, true)) return false;
if ($this->_init_header())
{
// always save v1 info
$this->_set_v1_info($pa);
// set v2 first if need
$this->_set_v2_info($pa);
}
$this->_file_deinit();
return true;
}
// get the header information[v1+v2], call after file_init
function _init_header()
{
$this->head1 = false;
$this->head = false;
// try to get ID3v1 first
fseek($this->fd, -128, SEEK_END);
$buf = fread($this->fd, 128);
if (strlen($buf) == 128 && substr($buf, 0, 3) == "TAG")
{
$tmp = unpack("a3id/a30Title/a30Artist/a30AlbumTitle/a4Year/a28Description/CReserved/CTrack/CGenre", $buf);
$this->head1 = $tmp;
}
// try to get ID3v2
fseek($this->fd, 0, SEEK_SET);
$buf = fread($this->fd, 10);
if (strlen($buf) == 10 && substr($buf, 0, 3) == "ID3")
{
$tmp = unpack("a3id/Cver/Crev/Cflag/C4size", $buf);
$tmp["size"] = ($tmp["size1"]<<21)|($tmp["size2"]<<14)|($tmp["size3"]<<7)|$tmp["size4"];
unset($tmp["size1"], $tmp["size2"], $tmp["size3"], $tmp["size4"]);
$this->head = $tmp;
$this->head_buf = fread($this->fd, $tmp["size"]);
}
return ($this->head1 || $this->head);
}
// get v1 info
function _get_v1_info()
{
$ret = array();
$tmpa = array("Title", "Artist", "Copyright", "Description", "Year", "AlbumTitle");
foreach ($tmpa as $tmp)
{
$ret[$tmp] = $this->head1[$tmp];
if ($pos = strpos($ret[$tmp], ""))
$ret[$tmp] = substr($ret[$tmp], 0, $pos);
}
// count the Genre, [Track]
if ($this->head1["Reserved"] == 0) $ret["Track"] = $this->head1["Track"];
else $ret["Description"] .= chr($ret["Reserved"]) . chr($ret["Track"]);
// Genre_idx
$g = $this->head1["Genre"];
if (!isset($this->genres[$g])) $ret["Genre"] = "Unknown";
else $ret["Genre"] = $this->genres[$g];
// return the value
$ret["ID3v1"] = "yes";
return $ret;
}
// get v2 info
function _get_v2_info()
{
$ret = array();
$items = array( "TCOP"=>"Copyright", "TPE1"=>"Artist", "TIT2"=>"Title", "TRCK"=> "Track",
"TCON"=>"Genre", "COMM"=>"Description", "TYER"=>"Year", "TALB"=>"AlbumTitle");
while (true)
{
$buf = $this->_read_head_buf(10);
if (strlen($buf) != 10) break;
$tmp = unpack("a4fid/Nsize/nflag", $buf);
if ($tmp["size"] == 0) break;
$tmp["dat"] = $this->_read_head_buf($tmp["size"]);
// 0x6000 (11000000 00000000)
if ($tmp["flag"] & 0x6000) continue;
// mapping the data
if ($k = $items[$tmp["fid"]])
{ // If first char is "", just skip
if (substr($tmp["dat"], 0, 1) == "") $tmp["dat"] = substr($tmp["dat"], 1);
$ret[$k] = $tmp["dat"];
}
}
// reset the genre
if ($g = $ret["Genre"])
{
if (substr($g,0,1) == "(" && substr($g,-1,1) == ")") $g = substr($g, 1, -1);
if (is_numeric($g))
{
$g = intval($g);
$ret["Genre"] = (isset($this->genres[$g]) ? $this->genres[$g] : "Unknown");
}
}
$ret["ID3v1"] = "no";
return $ret;
}
// get meta info of MP3
function _get_meta_info()
{
// seek to the lead buf: 0xff
$off = 0;
if ($this->head) $off = $this->head["size"] + 10;
fseek($this->fd, $off, SEEK_SET);
while (!feof($this->fd))
{
$skip = ord(fread($this->fd, 1));
if ($skip == 0xff) break;
}
if ($skip != 0xff) return false;
$buf = fread($this->fd, 3);
if (strlen($buf) != 3) return false;
$tmp = unpack("C3", $buf);
if (($tmp[1] & 0xf0) != 0xf0) return false;
// get the meta info
$meta = array();
// get mpeg version
$meta["mpeg"] = ($tmp[1] & 0x08 ? 1 : 2);
$meta["layer"] = ($tmp[1] & 0x04) ? (($tmp[1] & 0x02) ? 1 : 2) : (($tmp[1] & 0x02) ? 3 : 0);
$meta["epro"] = ($tmp[1] & 0x01) ? "no" : "yes";
// bit rates
$bit_rates = array(
1 => array(
1 => array(0,32,64,96,128,160,192,224,256,288,320,352,384,416,448,0),
2 => array(0,32,48,56,64,80,96,112,128,160,192,224,256,320,384,0),
3 => array(0,32,40,48,56,64,80,96,112,128,160,192,224,256,320,0)
),
2 => array(
1 => array(0,32,48,56,64,80,96,112,128,144,160,176,192,224,256,0),
2 => array(0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,0),
3 => array(0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,0)
)
);
$i = $meta["mpeg"];
$j = $meta["layer"];
$k = ($tmp[2]>>4);
$meta["bitrate"] = $bit_rates[$i][$j][$k];
// sample rates <采样率>
$sam_rates = array(1=>array(44100,48000,32000,0), 2=>array(22050,24000,16000,0));
$meta["samrate"] = $sam_rates[$i][$k];
$meta["padding"] = ($tmp[2] & 0x02) ? "on" : "off";
$meta["private"] = ($tmp[2] & 0x01) ? "on" : "off";
// mode & mode_ext
$k = ($tmp[3]>>6);
$channel_modes = array("stereo", "joint stereo", "dual channel", "single channel");
$meta["mode"] = $channel_modes[$k];
$k = (($tmp[3]>>4) & 0x03);
$extend_modes = array("MPG_MD_LR_LR", "MPG_MD_LR_I", "MPG_MD_MS_LR", "MPG_MD_MS_I");
$meta["ext_mode"] = $extend_modes[$k];
$meta["copyright"] = ($tmp[3] & 0x08) ? "yes" : "no";
$meta["original"] = ($tmp[3] & 0x04) ? "yes" : "no";
$emphasis = array("none", "50/15 microsecs", "rreserved", "CCITT J 17");
$k = ($tmp[3] & 0x03);
$meta["emphasis"] = $emphasis[$k];
return $meta;
}
// set v1 info
function _set_v1_info($pa)
{
// ID3v1 (simpled)
$off = -128;
if (!($tmp = $this->head1))
{
$off = 0;
$tmp["id"] = "TAG";
$tmp["Title"] = $tmp["Artist"] = $tmp["AlbumTitle"] = $tmp["Year"] = $tmp["Description"] = "";
$tmp["Reserved"] = $tmp["Track"] = $tmp["Genre"] = 0;
} // basic items
$items = array("Title", "Artist", "Copyright", "Description", "Year", "AlbumTitle");
foreach ($items as $k)
{
if (isset($pa[$k])) $tmp[$k] = $pa[$k];
}
// genre index
if (isset($pa["Genre"]))
{
$g = 0;
foreach ($this->genres as $gtmp)
{
if (!strcasecmp($gtmp, $pa["Genre"]))
break;
$g++;
}
$tmp["Genre"] = $g;
}
if (isset($pa["Track"])) $tmp["Track"] = intval($pa["Track"]);
// pack the data
$buf = pack("a3a30a30a30a4a28CCC", $tmp["id"], $tmp["Title"], $tmp["Artist"], $tmp["AlbumTitle"],
$tmp["Year"], $tmp["Description"], 0, $tmp["Track"], $tmp["Genre"]);
flock($this->fd, LOCK_EX);
fseek($this->fd, $off, SEEK_END);
fwrite($this->fd, $buf, 128);
flock($this->fd, LOCK_UN);
}
// set v2 info
function _set_v2_info($pa)
{
if (!$this->head)
{ // insert ID3
return; // 没有就算了
/**
$tmp = array("id"=>"ID3","ver"=>3,"rev"=>0,"flag"=>0);
$tmp["size"] = -10; // +10 => 0
$this->head = $tmp;
$this->head_buf = "";
$this->head_off = 0;
**/
}
$items = array( "TCOP"=>"Copyright", "TPE1"=>"Artist", "TIT2"=>"Title", "TRAC"=>"Track",
"TCON"=>"Genre", "COMM"=>"Description", "TYER"=>"Year", "TALB"=>"AlbumTitle");
$head_body = "";
while (true)
{
$buf = $this->_read_head_buf(10);
if (strlen($buf) != 10) break;
$tmp = unpack("a4fid/Nsize/nflag", $buf);
if ($tmp["size"] == 0) break;
$data = $this->_read_head_buf($tmp["size"]);
if (($k = $items[$tmp["fid"]]) && isset($pa[$k]))
{
// the data should prefix by "" [replace]
$data = "" . $pa[$k];
unset($pa[$k]);
}
$head_body .= pack("a4Nn", $tmp["fid"], strlen($data), $tmp["flag"]) . $data;
}
// reverse the items & set the new tags
$items = array_flip($items);
foreach ($pa as $k => $v)
{
if ($fid = $items[$k])
{
$head_body .= pack("a4Nn", $fid, strlen($v) + 1, 0) . "" . $v;
}
}
// new length
$new_len = strlen($head_body) + 10;
$old_len = $this->head["size"] + 10;
if ($new_len < $old_len)
{
$head_body .= str_repeat("", $old_len - $new_len);
$new_len = $old_len;
}
// count the size1,2,3,4, no include the header
// 较为变态的算法... :p (28bytes integer)
$size = array();
$nlen = $new_len - 10;
for ($i = 4; $i > 0; $i--)
{
$size[$i] = ($nlen & 0x7f);
$nlen >>= 7;
}
$tmp = $this->head;
//echo "old_len : $old_len new_len: $new_len ";
$head_buf = pack("a3CCCCCCC", $tmp["id"], $tmp["ver"], $tmp["rev"], $tmp["flag"],
$size[1], $size[2], $size[3], $size[4]);
$head_buf .= $head_body;
$this->_file_save($head_buf, $old_len, $new_len);
}
}
?>
