$headerstring .= chr(hexdec($textbyte));
}
$MP3fileInfo['error'] = '';
$MPEGheaderRawArray = MPEGaudioHeaderDecode(substr($headerstring, 0, 4));
if (MPEGaudioHeaderValid($MPEGheaderRawArray, true)) {
$MP3fileInfo['raw'] = $MPEGheaderRawArray;
$MP3fileInfo['version'] = MPEGaudioVersionLookup($MP3fileInfo['raw']['version']);
$MP3fileInfo['layer'] = MPEGaudioLayerLookup($MP3fileInfo['raw']['layer']);
$MP3fileInfo['protection'] = MPEGaudioCRCLookup($MP3fileInfo['raw']['protection']);
$MP3fileInfo['bitrate'] = MPEGaudioBitrateLookup($MP3fileInfo['version'], $MP3fileInfo['layer'], $MP3fileInfo['raw']['bitrate']);
$MP3fileInfo['frequency'] = MPEGaudioFrequencyLookup($MP3fileInfo['version'], $MP3fileInfo['raw']['sample_rate']);
$MP3fileInfo['padding'] = (bool) $MP3fileInfo['raw']['padding'];
$MP3fileInfo['private'] = (bool) $MP3fileInfo['raw']['private'];
$MP3fileInfo['channelmode'] = MPEGaudioChannelModeLookup($MP3fileInfo['raw']['channelmode']);
$MP3fileInfo['channels'] = $MP3fileInfo['channelmode'] == 'mono' ? 1 : 2;
$MP3fileInfo['modeextension'] = MPEGaudioModeExtensionLookup($MP3fileInfo['layer'], $MP3fileInfo['raw']['modeextension']);
$MP3fileInfo['copyright'] = (bool) $MP3fileInfo['raw']['copyright'];
$MP3fileInfo['original'] = (bool) $MP3fileInfo['raw']['original'];
$MP3fileInfo['emphasis'] = MPEGaudioEmphasisLookup($MP3fileInfo['raw']['emphasis']);
if ($MP3fileInfo['protection']) {
$MP3fileInfo['crc'] = BigEndian2Int(substr($headerstring, 4, 2));
}
if ($MP3fileInfo['frequency'] > 0) {
$MP3fileInfo['framelength'] = MPEGaudioFrameLength($MP3fileInfo['bitrate'], $MP3fileInfo['version'], $MP3fileInfo['layer'], (int) $MP3fileInfo['padding'], $MP3fileInfo['frequency']);
}
if ($MP3fileInfo['bitrate'] != 'free') {
$MP3fileInfo['bitrate'] *= 1000;
}
} else {
$MP3fileInfo['error'] .= "\n" . 'Invalid MPEG audio header';
}
function MPEGaudioHeaderValid($rawarray)
{
$decodedVersion = MPEGaudioVersionLookup($rawarray['version']);
$decodedLayer = MPEGaudioLayerLookup($rawarray['layer']);
if ($decodedVersion === FALSE) {
return FALSE;
}
if ($decodedLayer === FALSE) {
return FALSE;
}
if (MPEGaudioBitrateLookup($decodedVersion, $decodedLayer, $rawarray['bitrate']) === FALSE) {
return FALSE;
}
if (MPEGaudioFrequencyLookup($decodedVersion, $rawarray['frequency']) === FALSE) {
return FALSE;
}
if (MPEGaudioChannelModeLookup($rawarray['channelmode']) === FALSE) {
return FALSE;
}
if (MPEGaudioModeExtensionLookup($decodedLayer, $rawarray['modeextension']) === FALSE) {
return FALSE;
}
if (MPEGaudioEmphasisLookup($rawarray['emphasis']) === FALSE) {
return FALSE;
}
// These are just either set or not set, you can't mess that up :)
// $rawarray['protection'];
// $rawarray['padding'];
// $rawarray['private'];
// $rawarray['copyright'];
// $rawarray['original'];
return TRUE;
}
