Файл: sys/inc/libs/getid3/module.audio.mpc.php
Строк: 614
<?php
/////////////////////////////////////////////////////////////////
/// getID3() by James Heinrich <info@getid3.org> //
// available at https://github.com/JamesHeinrich/getID3 //
// or https://www.getid3.org //
// or http://getid3.sourceforge.net //
// see readme.txt for more details //
/////////////////////////////////////////////////////////////////
// //
// module.audio.mpc.php //
// module for analyzing Musepack/MPEG+ Audio files //
// dependencies: NONE //
// ///
/////////////////////////////////////////////////////////////////
class getid3_mpc extends getid3_handler
{
/**
* @return bool
*/
public function Analyze() {
$info = &$this->getid3->info;
$info['mpc']['header'] = array();
$thisfile_mpc_header = &$info['mpc']['header'];
$info['fileformat'] = 'mpc';
$info['audio']['dataformat'] = 'mpc';
$info['audio']['bitrate_mode'] = 'vbr';
$info['audio']['channels'] = 2; // up to SV7 the format appears to have been hardcoded for stereo only
$info['audio']['lossless'] = false;
$this->fseek($info['avdataoffset']);
$MPCheaderData = $this->fread(4);
$info['mpc']['header']['preamble'] = substr($MPCheaderData, 0, 4); // should be 'MPCK' (SV8) or 'MP+' (SV7), otherwise possible stream data (SV4-SV6)
if (preg_match('#^MPCK#', $info['mpc']['header']['preamble'])) {
// this is SV8
return $this->ParseMPCsv8();
} elseif (preg_match('#^MP+#', $info['mpc']['header']['preamble'])) {
// this is SV7
return $this->ParseMPCsv7();
} elseif (preg_match('/^[x00x01x10x11x40x41x50x51x80x81x90x91xC0xC1xD0xD1][x20-37][x00x20x40x60x80xA0xC0xE0]/s', $MPCheaderData)) {
// this is SV4 - SV6, handle seperately
return $this->ParseMPCsv6();
} else {
$this->error('Expecting "MP+" or "MPCK" at offset '.$info['avdataoffset'].', found "'.getid3_lib::PrintHexBytes(substr($MPCheaderData, 0, 4)).'"');
unset($info['fileformat']);
unset($info['mpc']);
return false;
}
}
/**
* @return bool
*/
public function ParseMPCsv8() {
// this is SV8
// http://trac.musepack.net/trac/wiki/SV8Specification
$info = &$this->getid3->info;
$thisfile_mpc_header = &$info['mpc']['header'];
$keyNameSize = 2;
$maxHandledPacketLength = 9; // specs say: "n*8; 0 < n < 10"
$offset = $this->ftell();
while ($offset < $info['avdataend']) {
$thisPacket = array();
$thisPacket['offset'] = $offset;
$packet_offset = 0;
// Size is a variable-size field, could be 1-4 bytes (possibly more?)
// read enough data in and figure out the exact size later
$MPCheaderData = $this->fread($keyNameSize + $maxHandledPacketLength);
$packet_offset += $keyNameSize;
$thisPacket['key'] = substr($MPCheaderData, 0, $keyNameSize);
$thisPacket['key_name'] = $this->MPCsv8PacketName($thisPacket['key']);
if ($thisPacket['key'] == $thisPacket['key_name']) {
$this->error('Found unexpected key value "'.$thisPacket['key'].'" at offset '.$thisPacket['offset']);
return false;
}
$packetLength = 0;
$thisPacket['packet_size'] = $this->SV8variableLengthInteger(substr($MPCheaderData, $keyNameSize), $packetLength); // includes keyname and packet_size field
if ($thisPacket['packet_size'] === false) {
$this->error('Did not find expected packet length within '.$maxHandledPacketLength.' bytes at offset '.($thisPacket['offset'] + $keyNameSize));
return false;
}
$packet_offset += $packetLength;
$offset += $thisPacket['packet_size'];
switch ($thisPacket['key']) {
case 'SH': // Stream Header
$moreBytesToRead = $thisPacket['packet_size'] - $keyNameSize - $maxHandledPacketLength;
if ($moreBytesToRead > 0) {
$MPCheaderData .= $this->fread($moreBytesToRead);
}
$thisPacket['crc'] = getid3_lib::BigEndian2Int(substr($MPCheaderData, $packet_offset, 4));
$packet_offset += 4;
$thisPacket['stream_version'] = getid3_lib::BigEndian2Int(substr($MPCheaderData, $packet_offset, 1));
$packet_offset += 1;
$packetLength = 0;
$thisPacket['sample_count'] = $this->SV8variableLengthInteger(substr($MPCheaderData, $packet_offset, $maxHandledPacketLength), $packetLength);
$packet_offset += $packetLength;
$packetLength = 0;
$thisPacket['beginning_silence'] = $this->SV8variableLengthInteger(substr($MPCheaderData, $packet_offset, $maxHandledPacketLength), $packetLength);
$packet_offset += $packetLength;
$otherUsefulData = getid3_lib::BigEndian2Int(substr($MPCheaderData, $packet_offset, 2));
$packet_offset += 2;
$thisPacket['sample_frequency_raw'] = (($otherUsefulData & 0xE000) >> 13);
$thisPacket['max_bands_used'] = (($otherUsefulData & 0x1F00) >> 8);
$thisPacket['channels'] = (($otherUsefulData & 0x00F0) >> 4) + 1;
$thisPacket['ms_used'] = (bool) (($otherUsefulData & 0x0008) >> 3);
$thisPacket['audio_block_frames'] = (($otherUsefulData & 0x0007) >> 0);
$thisPacket['sample_frequency'] = $this->MPCfrequencyLookup($thisPacket['sample_frequency_raw']);
$thisfile_mpc_header['mid_side_stereo'] = $thisPacket['ms_used'];
$thisfile_mpc_header['sample_rate'] = $thisPacket['sample_frequency'];
$thisfile_mpc_header['samples'] = $thisPacket['sample_count'];
$thisfile_mpc_header['stream_version_major'] = $thisPacket['stream_version'];
$info['audio']['channels'] = $thisPacket['channels'];
$info['audio']['sample_rate'] = $thisPacket['sample_frequency'];
$info['playtime_seconds'] = $thisPacket['sample_count'] / $thisPacket['sample_frequency'];
$info['audio']['bitrate'] = (($info['avdataend'] - $info['avdataoffset']) * 8) / $info['playtime_seconds'];
break;
case 'RG': // Replay Gain
$moreBytesToRead = $thisPacket['packet_size'] - $keyNameSize - $maxHandledPacketLength;
if ($moreBytesToRead > 0) {
$MPCheaderData .= $this->fread($moreBytesToRead);
}
$thisPacket['replaygain_version'] = getid3_lib::BigEndian2Int(substr($MPCheaderData, $packet_offset, 1));
$packet_offset += 1;
$thisPacket['replaygain_title_gain'] = getid3_lib::BigEndian2Int(substr($MPCheaderData, $packet_offset, 2));
$packet_offset += 2;
$thisPacket['replaygain_title_peak'] = getid3_lib::BigEndian2Int(substr($MPCheaderData, $packet_offset, 2));
$packet_offset += 2;
$thisPacket['replaygain_album_gain'] = getid3_lib::BigEndian2Int(substr($MPCheaderData, $packet_offset, 2));
$packet_offset += 2;
$thisPacket['replaygain_album_peak'] = getid3_lib::BigEndian2Int(substr($MPCheaderData, $packet_offset, 2));
$packet_offset += 2;
if ($thisPacket['replaygain_title_gain']) { $info['replay_gain']['title']['gain'] = $thisPacket['replaygain_title_gain']; }
if ($thisPacket['replaygain_title_peak']) { $info['replay_gain']['title']['peak'] = $thisPacket['replaygain_title_peak']; }
if ($thisPacket['replaygain_album_gain']) { $info['replay_gain']['album']['gain'] = $thisPacket['replaygain_album_gain']; }
if ($thisPacket['replaygain_album_peak']) { $info['replay_gain']['album']['peak'] = $thisPacket['replaygain_album_peak']; }
break;
case 'EI': // Encoder Info
$moreBytesToRead = $thisPacket['packet_size'] - $keyNameSize - $maxHandledPacketLength;
if ($moreBytesToRead > 0) {
$MPCheaderData .= $this->fread($moreBytesToRead);
}
$profile_pns = getid3_lib::BigEndian2Int(substr($MPCheaderData, $packet_offset, 1));
$packet_offset += 1;
$quality_int = (($profile_pns & 0xF0) >> 4);
$quality_dec = (($profile_pns & 0x0E) >> 3);
$thisPacket['quality'] = (float) $quality_int + ($quality_dec / 8);
$thisPacket['pns_tool'] = (bool) (($profile_pns & 0x01) >> 0);
$thisPacket['version_major'] = getid3_lib::BigEndian2Int(substr($MPCheaderData, $packet_offset, 1));
$packet_offset += 1;
$thisPacket['version_minor'] = getid3_lib::BigEndian2Int(substr($MPCheaderData, $packet_offset, 1));
$packet_offset += 1;
$thisPacket['version_build'] = getid3_lib::BigEndian2Int(substr($MPCheaderData, $packet_offset, 1));
$packet_offset += 1;
$thisPacket['version'] = $thisPacket['version_major'].'.'.$thisPacket['version_minor'].'.'.$thisPacket['version_build'];
$info['audio']['encoder'] = 'MPC v'.$thisPacket['version'].' ('.(($thisPacket['version_minor'] % 2) ? 'unstable' : 'stable').')';
$thisfile_mpc_header['encoder_version'] = $info['audio']['encoder'];
//$thisfile_mpc_header['quality'] = (float) ($thisPacket['quality'] / 1.5875); // values can range from 0.000 to 15.875, mapped to qualities of 0.0 to 10.0
$thisfile_mpc_header['quality'] = (float) ($thisPacket['quality'] - 5); // values can range from 0.000 to 15.875, of which 0..4 are "reserved/experimental", and 5..15 are mapped to qualities of 0.0 to 10.0
break;
case 'SO': // Seek Table Offset
$packetLength = 0;
$thisPacket['seek_table_offset'] = $thisPacket['offset'] + $this->SV8variableLengthInteger(substr($MPCheaderData, $packet_offset, $maxHandledPacketLength), $packetLength);
$packet_offset += $packetLength;
break;
case 'ST': // Seek Table
case 'SE': // Stream End
case 'AP': // Audio Data
// nothing useful here, just skip this packet
$thisPacket = array();
break;
default:
$this->error('Found unhandled key type "'.$thisPacket['key'].'" at offset '.$thisPacket['offset']);
return false;
break;
}
if (!empty($thisPacket)) {
$info['mpc']['packets'][] = $thisPacket;
}
$this->fseek($offset);
}
$thisfile_mpc_header['size'] = $offset;
return true;
}
/**
* @return bool
*/
public function ParseMPCsv7() {
// this is SV7
// http://www.uni-jena.de/~pfk/mpp/sv8/header.html
$info = &$this->getid3->info;
$thisfile_mpc_header = &$info['mpc']['header'];
$offset = 0;
$thisfile_mpc_header['size'] = 28;
$MPCheaderData = $info['mpc']['header']['preamble'];
$MPCheaderData .= $this->fread($thisfile_mpc_header['size'] - strlen($info['mpc']['header']['preamble']));
$offset = strlen('MP+');
$StreamVersionByte = getid3_lib::LittleEndian2Int(substr($MPCheaderData, $offset, 1));
$offset += 1;
$thisfile_mpc_header['stream_version_major'] = ($StreamVersionByte & 0x0F) >> 0;
$thisfile_mpc_header['stream_version_minor'] = ($StreamVersionByte & 0xF0) >> 4; // should always be 0, subversions no longer exist in SV8
$thisfile_mpc_header['frame_count'] = getid3_lib::LittleEndian2Int(substr($MPCheaderData, $offset, 4));
$offset += 4;
if ($thisfile_mpc_header['stream_version_major'] != 7) {
$this->error('Only Musepack SV7 supported (this file claims to be v'.$thisfile_mpc_header['stream_version_major'].')');
return false;
}
$FlagsDWORD1 = getid3_lib::LittleEndian2Int(substr($MPCheaderData, $offset, 4));
$offset += 4;
$thisfile_mpc_header['intensity_stereo'] = (bool) (($FlagsDWORD1 & 0x80000000) >> 31);
$thisfile_mpc_header['mid_side_stereo'] = (bool) (($FlagsDWORD1 & 0x40000000) >> 30);
$thisfile_mpc_header['max_subband'] = ($FlagsDWORD1 & 0x3F000000) >> 24;
$thisfile_mpc_header['raw']['profile'] = ($FlagsDWORD1 & 0x00F00000) >> 20;
$thisfile_mpc_header['begin_loud'] = (bool) (($FlagsDWORD1 & 0x00080000) >> 19);
$thisfile_mpc_header['end_loud'] = (bool) (($FlagsDWORD1 & 0x00040000) >> 18);
$thisfile_mpc_header['raw']['sample_rate'] = ($FlagsDWORD1 & 0x00030000) >> 16;
$thisfile_mpc_header['max_level'] = ($FlagsDWORD1 & 0x0000FFFF);
$thisfile_mpc_header['raw']['title_peak'] = getid3_lib::LittleEndian2Int(substr($MPCheaderData, $offset, 2));
$offset += 2;
$thisfile_mpc_header['raw']['title_gain'] = getid3_lib::LittleEndian2Int(substr($MPCheaderData, $offset, 2), true);
$offset += 2;
$thisfile_mpc_header['raw']['album_peak'] = getid3_lib::LittleEndian2Int(substr($MPCheaderData, $offset, 2));
$offset += 2;
$thisfile_mpc_header['raw']['album_gain'] = getid3_lib::LittleEndian2Int(substr($MPCheaderData, $offset, 2), true);
$offset += 2;
$FlagsDWORD2 = getid3_lib::LittleEndian2Int(substr($MPCheaderData, $offset, 4));
$offset += 4;
$thisfile_mpc_header['true_gapless'] = (bool) (($FlagsDWORD2 & 0x80000000) >> 31);
$thisfile_mpc_header['last_frame_length'] = ($FlagsDWORD2 & 0x7FF00000) >> 20;
$thisfile_mpc_header['raw']['not_sure_what'] = getid3_lib::LittleEndian2Int(substr($MPCheaderData, $offset, 3));
$offset += 3;
$thisfile_mpc_header['raw']['encoder_version'] = getid3_lib::LittleEndian2Int(substr($MPCheaderData, $offset, 1));
$offset += 1;
$thisfile_mpc_header['profile'] = $this->MPCprofileNameLookup($thisfile_mpc_header['raw']['profile']);
$thisfile_mpc_header['sample_rate'] = $this->MPCfrequencyLookup($thisfile_mpc_header['raw']['sample_rate']);
if ($thisfile_mpc_header['sample_rate'] == 0) {
$this->error('Corrupt MPC file: frequency == zero');
return false;
}
$info['audio']['sample_rate'] = $thisfile_mpc_header['sample_rate'];
$thisfile_mpc_header['samples'] = ((($thisfile_mpc_header['frame_count'] - 1) * 1152) + $thisfile_mpc_header['last_frame_length']) * $info['audio']['channels'];
$info['playtime_seconds'] = ($thisfile_mpc_header['samples'] / $info['audio']['channels']) / $info['audio']['sample_rate'];
if ($info['playtime_seconds'] == 0) {
$this->error('Corrupt MPC file: playtime_seconds == zero');
return false;
}
// add size of file header to avdataoffset - calc bitrate correctly + MD5 data
$info['avdataoffset'] += $thisfile_mpc_header['size'];
$info['audio']['bitrate'] = (($info['avdataend'] - $info['avdataoffset']) * 8) / $info['playtime_seconds'];
$thisfile_mpc_header['title_peak'] = $thisfile_mpc_header['raw']['title_peak'];
$thisfile_mpc_header['title_peak_db'] = $this->MPCpeakDBLookup($thisfile_mpc_header['title_peak']);
if ($thisfile_mpc_header['raw']['title_gain'] < 0) {
$thisfile_mpc_header['title_gain_db'] = (float) (32768 + $thisfile_mpc_header['raw']['title_gain']) / -100;
} else {
$thisfile_mpc_header['title_gain_db'] = (float) $thisfile_mpc_header['raw']['title_gain'] / 100;
}
$thisfile_mpc_header['album_peak'] = $thisfile_mpc_header['raw']['album_peak'];
$thisfile_mpc_header['album_peak_db'] = $this->MPCpeakDBLookup($thisfile_mpc_header['album_peak']);
if ($thisfile_mpc_header['raw']['album_gain'] < 0) {
$thisfile_mpc_header['album_gain_db'] = (float) (32768 + $thisfile_mpc_header['raw']['album_gain']) / -100;
} else {
$thisfile_mpc_header['album_gain_db'] = (float) $thisfile_mpc_header['raw']['album_gain'] / 100;;
}
$thisfile_mpc_header['encoder_version'] = $this->MPCencoderVersionLookup($thisfile_mpc_header['raw']['encoder_version']);
$info['replay_gain']['track']['adjustment'] = $thisfile_mpc_header['title_gain_db'];
$info['replay_gain']['album']['adjustment'] = $thisfile_mpc_header['album_gain_db'];
if ($thisfile_mpc_header['title_peak'] > 0) {
$info['replay_gain']['track']['peak'] = $thisfile_mpc_header['title_peak'];
} elseif (round($thisfile_mpc_header['max_level'] * 1.18) > 0) {
$info['replay_gain']['track']['peak'] = getid3_lib::CastAsInt(round($thisfile_mpc_header['max_level'] * 1.18)); // why? I don't know - see mppdec.c
}
if ($thisfile_mpc_header['album_peak'] > 0) {
$info['replay_gain']['album']['peak'] = $thisfile_mpc_header['album_peak'];
}
//$info['audio']['encoder'] = 'SV'.$thisfile_mpc_header['stream_version_major'].'.'.$thisfile_mpc_header['stream_version_minor'].', '.$thisfile_mpc_header['encoder_version'];
$info['audio']['encoder'] = $thisfile_mpc_header['encoder_version'];
$info['audio']['encoder_options'] = $thisfile_mpc_header['profile'];
$thisfile_mpc_header['quality'] = (float) ($thisfile_mpc_header['raw']['profile'] - 5); // values can range from 0 to 15, of which 0..4 are "reserved/experimental", and 5..15 are mapped to qualities of 0.0 to 10.0
return true;
}
/**
* @return bool
*/
public function ParseMPCsv6() {
// this is SV4 - SV6
$info = &$this->getid3->info;
$thisfile_mpc_header = &$info['mpc']['header'];
$offset = 0;
$thisfile_mpc_header['size'] = 8;
$this->fseek($info['avdataoffset']);
$MPCheaderData = $this->fread($thisfile_mpc_header['size']);
// add size of file header to avdataoffset - calc bitrate correctly + MD5 data
$info['avdataoffset'] += $thisfile_mpc_header['size'];
// Most of this code adapted from Jurgen Faul's MPEGplus source code - thanks Jurgen! :)
$HeaderDWORD[0] = getid3_lib::LittleEndian2Int(substr($MPCheaderData, 0, 4));
$HeaderDWORD[1] = getid3_lib::LittleEndian2Int(substr($MPCheaderData, 4, 4));
// DDDD DDDD CCCC CCCC BBBB BBBB AAAA AAAA
// aaaa aaaa abcd dddd dddd deee eeff ffff
//
// a = bitrate = anything
// b = IS = anything
// c = MS = anything
// d = streamversion = 0000000004 or 0000000005 or 0000000006
// e = maxband = anything
// f = blocksize = 000001 for SV5+, anything(?) for SV4
$thisfile_mpc_header['target_bitrate'] = (($HeaderDWORD[0] & 0xFF800000) >> 23);
$thisfile_mpc_header['intensity_stereo'] = (bool) (($HeaderDWORD[0] & 0x00400000) >> 22);
$thisfile_mpc_header['mid_side_stereo'] = (bool) (($HeaderDWORD[0] & 0x00200000) >> 21);
$thisfile_mpc_header['stream_version_major'] = ($HeaderDWORD[0] & 0x001FF800) >> 11;
$thisfile_mpc_header['stream_version_minor'] = 0; // no sub-version numbers before SV7
$thisfile_mpc_header['max_band'] = ($HeaderDWORD[0] & 0x000007C0) >> 6; // related to lowpass frequency, not sure how it translates exactly
$thisfile_mpc_header['block_size'] = ($HeaderDWORD[0] & 0x0000003F);
switch ($thisfile_mpc_header['stream_version_major']) {
case 4:
$thisfile_mpc_header['frame_count'] = ($HeaderDWORD[1] >> 16);
break;
case 5:
case 6:
$thisfile_mpc_header['frame_count'] = $HeaderDWORD[1];
break;
default:
$info['error'] = 'Expecting 4, 5 or 6 in version field, found '.$thisfile_mpc_header['stream_version_major'].' instead';
unset($info['mpc']);
return false;
break;
}
if (($thisfile_mpc_header['stream_version_major'] > 4) && ($thisfile_mpc_header['block_size'] != 1)) {
$this->warning('Block size expected to be 1, actual value found: '.$thisfile_mpc_header['block_size']);
}
$thisfile_mpc_header['sample_rate'] = 44100; // AB: used by all files up to SV7
$info['audio']['sample_rate'] = $thisfile_mpc_header['sample_rate'];
$thisfile_mpc_header['samples'] = $thisfile_mpc_header['frame_count'] * 1152 * $info['audio']['channels'];
if ($thisfile_mpc_header['target_bitrate'] == 0) {
$info['audio']['bitrate_mode'] = 'vbr';
} else {
$info['audio']['bitrate_mode'] = 'cbr';
}
$info['mpc']['bitrate'] = ($info['avdataend'] - $info['avdataoffset']) * 8 * 44100 / $thisfile_mpc_header['frame_count'] / 1152;
$info['audio']['bitrate'] = $info['mpc']['bitrate'];
$info['audio']['encoder'] = 'SV'.$thisfile_mpc_header['stream_version_major'];
return true;
}
/**
* @param int $profileid
*
* @return string
*/
public function MPCprofileNameLookup($profileid) {
static $MPCprofileNameLookup = array(
0 => 'no profile',
1 => 'Experimental',
2 => 'unused',
3 => 'unused',
4 => 'unused',
5 => 'below Telephone (q = 0.0)',
6 => 'below Telephone (q = 1.0)',
7 => 'Telephone (q = 2.0)',
8 => 'Thumb (q = 3.0)',
9 => 'Radio (q = 4.0)',
10 => 'Standard (q = 5.0)',
11 => 'Extreme (q = 6.0)',
12 => 'Insane (q = 7.0)',
13 => 'BrainDead (q = 8.0)',
14 => 'above BrainDead (q = 9.0)',
15 => 'above BrainDead (q = 10.0)'
);
return (isset($MPCprofileNameLookup[$profileid]) ? $MPCprofileNameLookup[$profileid] : 'invalid');
}
/**
* @param int $frequencyid
*
* @return int|string
*/
public function MPCfrequencyLookup($frequencyid) {
static $MPCfrequencyLookup = array(
0 => 44100,
1 => 48000,
2 => 37800,
3 => 32000
);
return (isset($MPCfrequencyLookup[$frequencyid]) ? $MPCfrequencyLookup[$frequencyid] : 'invalid');
}
/**
* @param int $intvalue
*
* @return float|false
*/
public function MPCpeakDBLookup($intvalue) {
if ($intvalue > 0) {
return ((log10($intvalue) / log10(2)) - 15) * 6;
}
return false;
}
/**
* @param int $encoderversion
*
* @return string
*/
public function MPCencoderVersionLookup($encoderversion) {
//Encoder version * 100 (106 = 1.06)
//EncoderVersion % 10 == 0 Release (1.0)
//EncoderVersion % 2 == 0 Beta (1.06)
//EncoderVersion % 2 == 1 Alpha (1.05a...z)
if ($encoderversion == 0) {
// very old version, not known exactly which
return 'Buschmann v1.7.0-v1.7.9 or Klemm v0.90-v1.05';
}
if (($encoderversion % 10) == 0) {
// release version
return number_format($encoderversion / 100, 2);
} elseif (($encoderversion % 2) == 0) {
// beta version
return number_format($encoderversion / 100, 2).' beta';
}
// alpha version
return number_format($encoderversion / 100, 2).' alpha';
}
/**
* @param string $data
* @param int $packetLength
* @param int $maxHandledPacketLength
*
* @return int|false
*/
public function SV8variableLengthInteger($data, &$packetLength, $maxHandledPacketLength=9) {
$packet_size = 0;
for ($packetLength = 1; $packetLength <= $maxHandledPacketLength; $packetLength++) {
// variable-length size field:
// bits, big-endian
// 0xxx xxxx - value 0 to 2^7-1
// 1xxx xxxx 0xxx xxxx - value 0 to 2^14-1
// 1xxx xxxx 1xxx xxxx 0xxx xxxx - value 0 to 2^21-1
// 1xxx xxxx 1xxx xxxx 1xxx xxxx 0xxx xxxx - value 0 to 2^28-1
// ...
$thisbyte = ord(substr($data, ($packetLength - 1), 1));
// look through bytes until find a byte with MSB==0
$packet_size = ($packet_size << 7);
$packet_size = ($packet_size | ($thisbyte & 0x7F));
if (($thisbyte & 0x80) === 0) {
break;
}
if ($packetLength >= $maxHandledPacketLength) {
return false;
}
}
return $packet_size;
}
/**
* @param string $packetKey
*
* @return string
*/
public function MPCsv8PacketName($packetKey) {
static $MPCsv8PacketName = array();
if (empty($MPCsv8PacketName)) {
$MPCsv8PacketName = array(
'AP' => 'Audio Packet',
'CT' => 'Chapter Tag',
'EI' => 'Encoder Info',
'RG' => 'Replay Gain',
'SE' => 'Stream End',
'SH' => 'Stream Header',
'SO' => 'Seek Table Offset',
'ST' => 'Seek Table',
);
}
return (isset($MPCsv8PacketName[$packetKey]) ? $MPCsv8PacketName[$packetKey] : $packetKey);
}
}