if (isset($_POST['Analyze']) && $_POST['HeaderHexBytes']) {
$headerbytearray = explode(' ', $_POST['HeaderHexBytes']);
if (count($headerbytearray) != 4) {
die('Invalid byte pattern');
}
$headerstring = '';
foreach ($headerbytearray as $textbyte) {
$headerstring .= chr(hexdec($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'], $MP3fileInfo['frequency']);
function decodeMPEGaudioHeader($fd, $offset, &$MP3fileInfo, $recursivesearch = TRUE)
{
if ($offset >= $MP3fileInfo['filesize']) {
$MP3fileInfo['error'] .= "\n" . 'end of file encounter looking for MPEG synch';
return FALSE;
}
fseek($fd, $offset, SEEK_SET);
$headerstring = fread($fd, FREAD_BUFFER_SIZE);
// MP3 audio frame structure:
// $aa $aa $aa $aa [$bb $bb] $cc...
// where $aa..$aa is the four-byte mpeg-audio header (below)
// $bb $bb is the optional 2-byte CRC
// and $cc... is the audio data
// AAAAAAAA AAABBCCD EEEEFFGH IIJJKLMM
// 01234567 01234567 01234567 01234567
// A - Frame sync (all bits set)
// B - MPEG Audio version ID
// C - Layer description
// D - Protection bit
// E - Bitrate index
// F - Sampling rate frequency index
// G - Padding bit
// H - Private bit
// I - Channel Mode
// J - Mode extension (Only if Joint stereo)
// K - Copyright
// L - Original
// M - Emphasis
$byte1 = BigEndian2Bin(substr($headerstring, 0, 1));
$byte2 = BigEndian2Bin(substr($headerstring, 1, 1));
$byte3 = BigEndian2Bin(substr($headerstring, 2, 1));
$byte4 = BigEndian2Bin(substr($headerstring, 3, 1));
if (substr(BigEndian2Bin(substr($headerstring, 0, 2)), 0, 11) == '11111111111') {
// synch detected (11 set bits in a row)
} else {
$MP3fileInfo['error'] .= "\n" . 'MPEG-audio synch not found where expected (at offset ' . $offset . ')';
return FALSE;
}
$MP3fileInfo['mpeg']['audio']['raw']['version'] = bindec(substr($byte2, 3, 2));
$MP3fileInfo['mpeg']['audio']['raw']['layer'] = bindec(substr($byte2, 5, 2));
$MP3fileInfo['mpeg']['audio']['raw']['protection'] = bindec(substr($byte2, 7, 1));
$MP3fileInfo['mpeg']['audio']['raw']['bitrate'] = bindec(substr($byte3, 0, 4));
$MP3fileInfo['mpeg']['audio']['raw']['frequency'] = bindec(substr($byte3, 4, 2));
$MP3fileInfo['mpeg']['audio']['raw']['padding'] = bindec(substr($byte3, 6, 1));
$MP3fileInfo['mpeg']['audio']['raw']['private'] = bindec(substr($byte3, 7, 1));
$MP3fileInfo['mpeg']['audio']['raw']['channelmode'] = bindec(substr($byte4, 0, 2));
$MP3fileInfo['mpeg']['audio']['raw']['modeextension'] = bindec(substr($byte4, 2, 2));
$MP3fileInfo['mpeg']['audio']['raw']['copyright'] = bindec(substr($byte4, 4, 1));
$MP3fileInfo['mpeg']['audio']['raw']['original'] = bindec(substr($byte4, 5, 1));
$MP3fileInfo['mpeg']['audio']['raw']['emphasis'] = bindec(substr($byte4, 6, 2));
if (!MPEGaudioHeaderValid($MP3fileInfo['mpeg']['audio']['raw'])) {
$MP3fileInfo['error'] .= "\n" . 'invalid MPEG audio header at offset ' . $offset;
return FALSE;
}
$MP3fileInfo['mpeg']['audio']['version'] = MPEGaudioVersionLookup($MP3fileInfo['mpeg']['audio']['raw']['version']);
$MP3fileInfo['mpeg']['audio']['layer'] = MPEGaudioLayerLookup($MP3fileInfo['mpeg']['audio']['raw']['layer']);
$MP3fileInfo['mpeg']['audio']['protection'] = MPEGaudioCRCLookup($MP3fileInfo['mpeg']['audio']['raw']['protection']);
$MP3fileInfo['mpeg']['audio']['bitrate'] = MPEGaudioBitrateLookup($MP3fileInfo['mpeg']['audio']['version'], $MP3fileInfo['mpeg']['audio']['layer'], $MP3fileInfo['mpeg']['audio']['raw']['bitrate']);
$MP3fileInfo['mpeg']['audio']['frequency'] = MPEGaudioFrequencyLookup($MP3fileInfo['mpeg']['audio']['version'], $MP3fileInfo['mpeg']['audio']['raw']['frequency']);
$MP3fileInfo['mpeg']['audio']['padding'] = (bool) $MP3fileInfo['mpeg']['audio']['raw']['padding'];
$MP3fileInfo['mpeg']['audio']['private'] = (bool) $MP3fileInfo['mpeg']['audio']['raw']['private'];
$MP3fileInfo['mpeg']['audio']['channelmode'] = MPEGaudioChannelModeLookup($MP3fileInfo['mpeg']['audio']['raw']['channelmode']);
$MP3fileInfo['mpeg']['audio']['channels'] = $MP3fileInfo['mpeg']['audio']['channelmode'] == 'mono' ? 1 : 2;
$MP3fileInfo['mpeg']['audio']['modeextension'] = MPEGaudioModeExtensionLookup($MP3fileInfo['mpeg']['audio']['layer'], $MP3fileInfo['mpeg']['audio']['raw']['modeextension']);
$MP3fileInfo['mpeg']['audio']['copyright'] = (bool) $MP3fileInfo['mpeg']['audio']['raw']['copyright'];
$MP3fileInfo['mpeg']['audio']['original'] = (bool) $MP3fileInfo['mpeg']['audio']['raw']['original'];
$MP3fileInfo['mpeg']['audio']['emphasis'] = MPEGaudioEmphasisLookup($MP3fileInfo['mpeg']['audio']['raw']['emphasis']);
if ($MP3fileInfo['mpeg']['audio']['protection']) {
$MP3fileInfo['mpeg']['audio']['crc'] = BigEndian2Int(substr($headerstring, 4, 2));
}
if ($MP3fileInfo['mpeg']['audio']['bitrate'] != 'free') {
if ($MP3fileInfo['mpeg']['audio']['version'] == '1') {
if ($MP3fileInfo['mpeg']['audio']['layer'] == 'I') {
$FrameLengthCoefficient = 48;
$FrameLengthPadding = $MP3fileInfo['mpeg']['audio']['padding'] ? 4 : 0;
// "For Layer I slot is 32 bits long, for Layer II and Layer III slot is 8 bits long."
} else {
// Layer II / III
$FrameLengthCoefficient = 144;
$FrameLengthPadding = $MP3fileInfo['mpeg']['audio']['padding'] ? 1 : 0;
// "For Layer I slot is 32 bits long, for Layer II and Layer III slot is 8 bits long."
}
} else {
// MPEG-2 / MPEG-2.5
if ($MP3fileInfo['mpeg']['audio']['layer'] == 'I') {
$FrameLengthCoefficient = 24;
$FrameLengthPadding = $MP3fileInfo['mpeg']['audio']['padding'] ? 4 : 0;
// "For Layer I slot is 32 bits long, for Layer II and Layer III slot is 8 bits long."
} else {
// Layer II / III
$FrameLengthCoefficient = 72;
$FrameLengthPadding = $MP3fileInfo['mpeg']['audio']['padding'] ? 1 : 0;
// "For Layer I slot is 32 bits long, for Layer II and Layer III slot is 8 bits long."
}
}
// FrameLengthInBytes = ((Coefficient * BitRate) / SampleRate) + Padding
// http://66.96.216.160/cgi-bin/YaBB.pl?board=c&action=display&num=1018474068
// -> "Finding the next frame synch" on www.r3mix.net forums if the above link goes dead
$MP3fileInfo['mpeg']['audio']['framelength'] = (int) floor($FrameLengthCoefficient * 1000 * $MP3fileInfo['mpeg']['audio']['bitrate'] / $MP3fileInfo['mpeg']['audio']['frequency']) + $FrameLengthPadding;
}
$MP3fileInfo['bitrate'] = 1000 * $MP3fileInfo['mpeg']['audio']['bitrate'];
$nextframetestarray = array('error' => '', 'filesize' => $MP3fileInfo['filesize']);
if (isset($MP3fileInfo['mpeg']['audio']['framelength'])) {
$nextframetestoffset = $offset + $MP3fileInfo['mpeg']['audio']['framelength'];
} else {
$nextframetestoffset = $MP3fileInfo['filesize'];
}
if ($recursivesearch && isset($MP3fileInfo['mpeg']['audio']['framelength']) && $MP3fileInfo['mpeg']['audio']['framelength']) {
for ($i = 0; $i < 5; $i++) {
// check next 5 frames for validity, to make sure we haven't run across a false synch
if ($nextframetestoffset >= $MP3fileInfo['filesize']) {
// end of file
break;
}
if (decodeMPEGaudioHeader($fd, $nextframetestoffset, $nextframetestarray, FALSE)) {
// next frame is OK, get ready to check the one after that
$nextframetestoffset += $nextframetestarray['mpeg']['audio']['framelength'];
} else {
// next frame is not valid, note the error and fail, so scanning can contiue for a valid frame sequence
$MP3fileInfo['error'] .= "\n" . 'Frame at offset(' . $offset . ') is valid, but the next one at (' . $nextframetestoffset . ') is not.';
return FALSE;
}
}
}
// For Layer II there are some combinations of bitrate and mode which are not allowed.
if ($MP3fileInfo['mpeg']['audio']['layer'] == 'II') {
switch ($MP3fileInfo['mpeg']['audio']['channelmode']) {
case 'mono':
if ($MP3fileInfo['mpeg']['audio']['bitrate'] == 'free' || $MP3fileInfo['mpeg']['audio']['bitrate'] <= 192) {
// these are ok
} else {
$MP3fileInfo['error'] .= "\n" . $MP3fileInfo['mpeg']['audio']['bitrate'] . 'kbps not allowed in Layer II, ' . $MP3fileInfo['mpeg']['audio']['channelmode'] . '.';
}
break;
case 'stereo':
case 'joint stereo':
case 'dual channel':
if ($MP3fileInfo['mpeg']['audio']['bitrate'] == 'free' || $MP3fileInfo['mpeg']['audio']['bitrate'] == 64 || $MP3fileInfo['mpeg']['audio']['bitrate'] >= 96) {
// these are ok
} else {
$MP3fileInfo['error'] .= "\n" . $MP3fileInfo['mpeg']['audio']['bitrate'] . 'kbps not allowed in Layer II, ' . $MP3fileInfo['mpeg']['audio']['channelmode'] . '.';
}
break;
}
}
////////////////////////////////////////////////////////////////////////////////////
// Variable-bitrate headers
if ($MP3fileInfo['mpeg']['audio']['version'] == '1') {
if ($MP3fileInfo['mpeg']['audio']['channelmode'] == 'mono') {
$VBRidOffset = 17 + 4;
// 21 bytes
} else {
$VBRidOffset = 32 + 4;
// 36 bytes
}
} else {
// 2 or 2.5
if ($MP3fileInfo['mpeg']['audio']['channelmode'] == 'mono') {
$VBRidOffset = 9 + 4;
// 13 bytes
} else {
$VBRidOffset = 17 + 4;
// 21 bytes
}
}
$VBRid = substr($headerstring, $VBRidOffset, 4);
if ($VBRid == 'Xing') {
$MP3fileInfo['mpeg']['audio']['bitratemode'] = 'VBR';
$MP3fileInfo['mpeg']['audio']['VBR_method'] = 'Xing';
} else {
if ($VBRid == 'VBRI') {
$MP3fileInfo['mpeg']['audio']['bitratemode'] = 'VBR';
$MP3fileInfo['mpeg']['audio']['VBR_method'] = 'Fraunhofer';
} else {
$MP3fileInfo['mpeg']['audio']['bitratemode'] = 'CBR';
}
}
if ($MP3fileInfo['mpeg']['audio']['bitratemode'] == 'VBR') {
if ($MP3fileInfo['mpeg']['audio']['VBR_method'] == 'Xing') {
$XingVBROffset = $VBRidOffset + 4;
$XingHeader_Flags = substr($headerstring, $XingVBROffset, 4);
$XingVBROffset += 4;
$XingHeader_byte4 = BigEndian2Bin(substr($XingHeader_Flags, 3, 1));
$XingHeader_flags['frames'] = substr($XingHeader_byte4, 4, 1);
$XingHeader_flags['bytes'] = substr($XingHeader_byte4, 5, 1);
$XingHeader_flags['toc'] = substr($XingHeader_byte4, 6, 1);
$XingHeader_flags['vbr_scale'] = substr($XingHeader_byte4, 7, 1);
if ($XingHeader_flags['frames'] == '1') {
$XingHeader_Frames = substr($headerstring, $XingVBROffset, 4);
$XingVBROffset += 4;
$MP3fileInfo['mpeg']['audio']['VBR_frames'] = BigEndian2Int($XingHeader_Frames);
}
if ($XingHeader_flags['bytes'] == '1') {
$XingHeader_Bytes = substr($headerstring, $XingVBROffset, 4);
$XingVBROffset += 4;
$MP3fileInfo['mpeg']['audio']['VBR_bytes'] = BigEndian2Int($XingHeader_Bytes);
}
} else {
if ($MP3fileInfo['mpeg']['audio']['VBR_method'] == 'Fraunhofer') {
// specs taken from http://minnie.tuhs.org/pipermail/mp3encoder/2001-January/001800.html
$FraunhoferVBROffset = $VBRidOffset + 4;
$Fraunhofer_version = substr($headerstring, $FraunhoferVBROffset, 4);
$FraunhoferVBROffset += 4;
$Fraunhofer_quality = substr($headerstring, $FraunhoferVBROffset, 2);
$FraunhoferVBROffset += 2;
$MP3fileInfo['mpeg']['audio']['VBR_quality'] = BigEndian2Int($Fraunhofer_quality);
$Fraunhofer_Bytes = substr($headerstring, $FraunhoferVBROffset, 4);
$FraunhoferVBROffset += 4;
$MP3fileInfo['mpeg']['audio']['VBR_bytes'] = BigEndian2Int($Fraunhofer_Bytes);
$Fraunhofer_Frames = substr($headerstring, $FraunhoferVBROffset, 4);
$FraunhoferVBROffset += 4;
$MP3fileInfo['mpeg']['audio']['VBR_frames'] = BigEndian2Int($Fraunhofer_Frames);
}
}
$MP3fileInfo['mpeg']['audio']['VBR_frames']--;
// don't count the Xing / VBRI frame
if ($MP3fileInfo['mpeg']['audio']['version'] == '1' && $MP3fileInfo['mpeg']['audio']['layer'] == 'I') {
$MP3fileInfo['mpeg']['audio']['VBR_bitrate'] = $MP3fileInfo['mpeg']['audio']['VBR_bytes'] / $MP3fileInfo['mpeg']['audio']['VBR_frames'] * 8 * ($MP3fileInfo['mpeg']['audio']['frequency'] / 384) / 1000;
} else {
if (($MP3fileInfo['mpeg']['audio']['version'] == '2' || $MP3fileInfo['mpeg']['audio']['version'] == '2.5') && $MP3fileInfo['mpeg']['audio']['layer'] == 'III') {
$MP3fileInfo['mpeg']['audio']['VBR_bitrate'] = $MP3fileInfo['mpeg']['audio']['VBR_bytes'] / $MP3fileInfo['mpeg']['audio']['VBR_frames'] * 8 * ($MP3fileInfo['mpeg']['audio']['frequency'] / 576) / 1000;
} else {
$MP3fileInfo['mpeg']['audio']['VBR_bitrate'] = $MP3fileInfo['mpeg']['audio']['VBR_bytes'] / $MP3fileInfo['mpeg']['audio']['VBR_frames'] * 8 * ($MP3fileInfo['mpeg']['audio']['frequency'] / 1152) / 1000;
}
}
if ($MP3fileInfo['mpeg']['audio']['VBR_bitrate'] > 0) {
$MP3fileInfo['bitrate'] = 1000 * $MP3fileInfo['mpeg']['audio']['VBR_bitrate'];
unset($MP3fileInfo['mpeg']['audio']['bitrate']);
// to avoid confusion
}
}
return TRUE;
}