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';
}
}
}