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WordPress/wp-includes/ID3/module.audio.ac3.php

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<?php
/////////////////////////////////////////////////////////////////
/// getID3() by James Heinrich <info@getid3.org> //
// available at http://getid3.sourceforge.net //
// or http://www.getid3.org //
// also https://github.com/JamesHeinrich/getID3 //
/////////////////////////////////////////////////////////////////
// See readme.txt for more details //
/////////////////////////////////////////////////////////////////
// //
// module.audio.ac3.php //
// module for analyzing AC-3 (aka Dolby Digital) audio files //
// dependencies: NONE //
// ///
/////////////////////////////////////////////////////////////////
class getid3_ac3 extends getid3_handler
{
private $AC3header = array();
private $BSIoffset = 0;
const syncword = 0x0B77;
public function Analyze() {
$info = &$this->getid3->info;
///AH
$info['ac3']['raw']['bsi'] = array();
$thisfile_ac3 = &$info['ac3'];
$thisfile_ac3_raw = &$thisfile_ac3['raw'];
$thisfile_ac3_raw_bsi = &$thisfile_ac3_raw['bsi'];
// http://www.atsc.org/standards/a_52a.pdf
$info['fileformat'] = 'ac3';
// An AC-3 serial coded audio bit stream is made up of a sequence of synchronization frames
// Each synchronization frame contains 6 coded audio blocks (AB), each of which represent 256
// new audio samples per channel. A synchronization information (SI) header at the beginning
// of each frame contains information needed to acquire and maintain synchronization. A
// bit stream information (BSI) header follows SI, and contains parameters describing the coded
// audio service. The coded audio blocks may be followed by an auxiliary data (Aux) field. At the
// end of each frame is an error check field that includes a CRC word for error detection. An
// additional CRC word is located in the SI header, the use of which, by a decoder, is optional.
//
// syncinfo() | bsi() | AB0 | AB1 | AB2 | AB3 | AB4 | AB5 | Aux | CRC
// syncinfo() {
// syncword 16
// crc1 16
// fscod 2
// frmsizecod 6
// } /* end of syncinfo */
$this->fseek($info['avdataoffset']);
$tempAC3header = $this->fread(100); // should be enough to cover all data, there are some variable-length fields...?
$this->AC3header['syncinfo'] = getid3_lib::BigEndian2Int(substr($tempAC3header, 0, 2));
$this->AC3header['bsi'] = getid3_lib::BigEndian2Bin(substr($tempAC3header, 2));
$thisfile_ac3_raw_bsi['bsid'] = (getid3_lib::LittleEndian2Int(substr($tempAC3header, 5, 1)) & 0xF8) >> 3; // AC3 and E-AC3 put the "bsid" version identifier in the same place, but unfortnately the 4 bytes between the syncword and the version identifier are interpreted differently, so grab it here so the following code structure can make sense
unset($tempAC3header);
if ($this->AC3header['syncinfo'] !== self::syncword) {
if (!$this->isDependencyFor('matroska')) {
unset($info['fileformat'], $info['ac3']);
return $this->error('Expecting "'.dechex(self::syncword).'" at offset '.$info['avdataoffset'].', found "'.dechex($this->AC3header['syncinfo']).'"');
}
}
$info['audio']['dataformat'] = 'ac3';
$info['audio']['bitrate_mode'] = 'cbr';
$info['audio']['lossless'] = false;
if ($thisfile_ac3_raw_bsi['bsid'] <= 8) {
$thisfile_ac3_raw_bsi['crc1'] = getid3_lib::Bin2Dec($this->readHeaderBSI(16));
$thisfile_ac3_raw_bsi['fscod'] = $this->readHeaderBSI(2); // 5.4.1.3
$thisfile_ac3_raw_bsi['frmsizecod'] = $this->readHeaderBSI(6); // 5.4.1.4
if ($thisfile_ac3_raw_bsi['frmsizecod'] > 37) { // binary: 100101 - see Table 5.18 Frame Size Code Table (1 word = 16 bits)
$this->warning('Unexpected ac3.bsi.frmsizecod value: '.$thisfile_ac3_raw_bsi['frmsizecod'].', bitrate not set correctly');
}
$thisfile_ac3_raw_bsi['bsid'] = $this->readHeaderBSI(5); // we already know this from pre-parsing the version identifier, but re-read it to let the bitstream flow as intended
$thisfile_ac3_raw_bsi['bsmod'] = $this->readHeaderBSI(3);
$thisfile_ac3_raw_bsi['acmod'] = $this->readHeaderBSI(3);
if ($thisfile_ac3_raw_bsi['acmod'] & 0x01) {
// If the lsb of acmod is a 1, center channel is in use and cmixlev follows in the bit stream.
$thisfile_ac3_raw_bsi['cmixlev'] = $this->readHeaderBSI(2);
$thisfile_ac3['center_mix_level'] = self::centerMixLevelLookup($thisfile_ac3_raw_bsi['cmixlev']);
}
if ($thisfile_ac3_raw_bsi['acmod'] & 0x04) {
// If the msb of acmod is a 1, surround channels are in use and surmixlev follows in the bit stream.
$thisfile_ac3_raw_bsi['surmixlev'] = $this->readHeaderBSI(2);
$thisfile_ac3['surround_mix_level'] = self::surroundMixLevelLookup($thisfile_ac3_raw_bsi['surmixlev']);
}
if ($thisfile_ac3_raw_bsi['acmod'] == 0x02) {
// When operating in the two channel mode, this 2-bit code indicates whether or not the program has been encoded in Dolby Surround.
$thisfile_ac3_raw_bsi['dsurmod'] = $this->readHeaderBSI(2);
$thisfile_ac3['dolby_surround_mode'] = self::dolbySurroundModeLookup($thisfile_ac3_raw_bsi['dsurmod']);
}
$thisfile_ac3_raw_bsi['flags']['lfeon'] = (bool) $this->readHeaderBSI(1);
// This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1-31.
// The value of 0 is reserved. The values of 1 to 31 are interpreted as -1 dB to -31 dB with respect to digital 100 percent.
$thisfile_ac3_raw_bsi['dialnorm'] = $this->readHeaderBSI(5); // 5.4.2.8 dialnorm: Dialogue Normalization, 5 Bits
$thisfile_ac3_raw_bsi['flags']['compr'] = (bool) $this->readHeaderBSI(1); // 5.4.2.9 compre: Compression Gain Word Exists, 1 Bit
if ($thisfile_ac3_raw_bsi['flags']['compr']) {
$thisfile_ac3_raw_bsi['compr'] = $this->readHeaderBSI(8); // 5.4.2.10 compr: Compression Gain Word, 8 Bits
$thisfile_ac3['heavy_compression'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr']);
}
$thisfile_ac3_raw_bsi['flags']['langcod'] = (bool) $this->readHeaderBSI(1); // 5.4.2.11 langcode: Language Code Exists, 1 Bit
if ($thisfile_ac3_raw_bsi['flags']['langcod']) {
$thisfile_ac3_raw_bsi['langcod'] = $this->readHeaderBSI(8); // 5.4.2.12 langcod: Language Code, 8 Bits
}
$thisfile_ac3_raw_bsi['flags']['audprodinfo'] = (bool) $this->readHeaderBSI(1); // 5.4.2.13 audprodie: Audio Production Information Exists, 1 Bit
if ($thisfile_ac3_raw_bsi['flags']['audprodinfo']) {
$thisfile_ac3_raw_bsi['mixlevel'] = $this->readHeaderBSI(5); // 5.4.2.14 mixlevel: Mixing Level, 5 Bits
$thisfile_ac3_raw_bsi['roomtyp'] = $this->readHeaderBSI(2); // 5.4.2.15 roomtyp: Room Type, 2 Bits
$thisfile_ac3['mixing_level'] = (80 + $thisfile_ac3_raw_bsi['mixlevel']).'dB';
$thisfile_ac3['room_type'] = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp']);
}
$thisfile_ac3_raw_bsi['dialnorm2'] = $this->readHeaderBSI(5); // 5.4.2.16 dialnorm2: Dialogue Normalization, ch2, 5 Bits
$thisfile_ac3['dialogue_normalization2'] = '-'.$thisfile_ac3_raw_bsi['dialnorm2'].'dB'; // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1-31. The value of 0 is reserved. The values of 1 to 31 are interpreted as -1 dB to -31 dB with respect to digital 100 percent.
$thisfile_ac3_raw_bsi['flags']['compr2'] = (bool) $this->readHeaderBSI(1); // 5.4.2.17 compr2e: Compression Gain Word Exists, ch2, 1 Bit
if ($thisfile_ac3_raw_bsi['flags']['compr2']) {
$thisfile_ac3_raw_bsi['compr2'] = $this->readHeaderBSI(8); // 5.4.2.18 compr2: Compression Gain Word, ch2, 8 Bits
$thisfile_ac3['heavy_compression2'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr2']);
}
$thisfile_ac3_raw_bsi['flags']['langcod2'] = (bool) $this->readHeaderBSI(1); // 5.4.2.19 langcod2e: Language Code Exists, ch2, 1 Bit
if ($thisfile_ac3_raw_bsi['flags']['langcod2']) {
$thisfile_ac3_raw_bsi['langcod2'] = $this->readHeaderBSI(8); // 5.4.2.20 langcod2: Language Code, ch2, 8 Bits
}
$thisfile_ac3_raw_bsi['flags']['audprodinfo2'] = (bool) $this->readHeaderBSI(1); // 5.4.2.21 audprodi2e: Audio Production Information Exists, ch2, 1 Bit
if ($thisfile_ac3_raw_bsi['flags']['audprodinfo2']) {
$thisfile_ac3_raw_bsi['mixlevel2'] = $this->readHeaderBSI(5); // 5.4.2.22 mixlevel2: Mixing Level, ch2, 5 Bits
$thisfile_ac3_raw_bsi['roomtyp2'] = $this->readHeaderBSI(2); // 5.4.2.23 roomtyp2: Room Type, ch2, 2 Bits
$thisfile_ac3['mixing_level2'] = (80 + $thisfile_ac3_raw_bsi['mixlevel2']).'dB';
$thisfile_ac3['room_type2'] = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp2']);
}
$thisfile_ac3_raw_bsi['copyright'] = (bool) $this->readHeaderBSI(1); // 5.4.2.24 copyrightb: Copyright Bit, 1 Bit
$thisfile_ac3_raw_bsi['original'] = (bool) $this->readHeaderBSI(1); // 5.4.2.25 origbs: Original Bit Stream, 1 Bit
$thisfile_ac3_raw_bsi['flags']['timecod1'] = $this->readHeaderBSI(2); // 5.4.2.26 timecod1e, timcode2e: Time Code (first and second) Halves Exist, 2 Bits
if ($thisfile_ac3_raw_bsi['flags']['timecod1'] & 0x01) {
$thisfile_ac3_raw_bsi['timecod1'] = $this->readHeaderBSI(14); // 5.4.2.27 timecod1: Time code first half, 14 bits
$thisfile_ac3['timecode1'] = 0;
$thisfile_ac3['timecode1'] += (($thisfile_ac3_raw_bsi['timecod1'] & 0x3E00) >> 9) * 3600; // The first 5 bits of this 14-bit field represent the time in hours, with valid values of 0<>23
$thisfile_ac3['timecode1'] += (($thisfile_ac3_raw_bsi['timecod1'] & 0x01F8) >> 3) * 60; // The next 6 bits represent the time in minutes, with valid values of 0<>59
$thisfile_ac3['timecode1'] += (($thisfile_ac3_raw_bsi['timecod1'] & 0x0003) >> 0) * 8; // The final 3 bits represents the time in 8 second increments, with valid values of 0<>7 (representing 0, 8, 16, ... 56 seconds)
}
if ($thisfile_ac3_raw_bsi['flags']['timecod1'] & 0x02) {
$thisfile_ac3_raw_bsi['timecod2'] = $this->readHeaderBSI(14); // 5.4.2.28 timecod2: Time code second half, 14 bits
$thisfile_ac3['timecode2'] = 0;
$thisfile_ac3['timecode2'] += (($thisfile_ac3_raw_bsi['timecod2'] & 0x3800) >> 11) * 1; // The first 3 bits of this 14-bit field represent the time in seconds, with valid values from 0<>7 (representing 0-7 seconds)
$thisfile_ac3['timecode2'] += (($thisfile_ac3_raw_bsi['timecod2'] & 0x07C0) >> 6) * (1 / 30); // The next 5 bits represents the time in frames, with valid values from 0<>29 (one frame = 1/30th of a second)
$thisfile_ac3['timecode2'] += (($thisfile_ac3_raw_bsi['timecod2'] & 0x003F) >> 0) * ((1 / 30) / 60); // The final 6 bits represents fractions of 1/64 of a frame, with valid values from 0<>63
}
$thisfile_ac3_raw_bsi['flags']['addbsi'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['addbsi']) {
$thisfile_ac3_raw_bsi['addbsi_length'] = $this->readHeaderBSI(6) + 1; // This 6-bit code, which exists only if addbside is a 1, indicates the length in bytes of additional bit stream information. The valid range of addbsil is 0<>63, indicating 1<>64 additional bytes, respectively.
$this->AC3header['bsi'] .= getid3_lib::BigEndian2Bin($this->fread($thisfile_ac3_raw_bsi['addbsi_length']));
$thisfile_ac3_raw_bsi['addbsi_data'] = substr($this->AC3header['bsi'], $this->BSIoffset, $thisfile_ac3_raw_bsi['addbsi_length'] * 8);
$this->BSIoffset += $thisfile_ac3_raw_bsi['addbsi_length'] * 8;
}
} elseif ($thisfile_ac3_raw_bsi['bsid'] <= 16) { // E-AC3
$this->error('E-AC3 parsing is incomplete and experimental in this version of getID3 ('.$this->getid3->version().'). Notably the bitrate calculations are wrong -- value might (or not) be correct, but it is not calculated correctly. Email info@getid3.org if you know how to calculate EAC3 bitrate correctly.');
$info['audio']['dataformat'] = 'eac3';
$thisfile_ac3_raw_bsi['strmtyp'] = $this->readHeaderBSI(2);
$thisfile_ac3_raw_bsi['substreamid'] = $this->readHeaderBSI(3);
$thisfile_ac3_raw_bsi['frmsiz'] = $this->readHeaderBSI(11);
$thisfile_ac3_raw_bsi['fscod'] = $this->readHeaderBSI(2);
if ($thisfile_ac3_raw_bsi['fscod'] == 3) {
$thisfile_ac3_raw_bsi['fscod2'] = $this->readHeaderBSI(2);
$thisfile_ac3_raw_bsi['numblkscod'] = 3; // six blocks per syncframe
} else {
$thisfile_ac3_raw_bsi['numblkscod'] = $this->readHeaderBSI(2);
}
$thisfile_ac3['bsi']['blocks_per_sync_frame'] = self::blocksPerSyncFrame($thisfile_ac3_raw_bsi['numblkscod']);
$thisfile_ac3_raw_bsi['acmod'] = $this->readHeaderBSI(3);
$thisfile_ac3_raw_bsi['flags']['lfeon'] = (bool) $this->readHeaderBSI(1);
$thisfile_ac3_raw_bsi['bsid'] = $this->readHeaderBSI(5); // we already know this from pre-parsing the version identifier, but re-read it to let the bitstream flow as intended
$thisfile_ac3_raw_bsi['dialnorm'] = $this->readHeaderBSI(5);
$thisfile_ac3_raw_bsi['flags']['compr'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['compr']) {
$thisfile_ac3_raw_bsi['compr'] = $this->readHeaderBSI(8);
}
if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value)
$thisfile_ac3_raw_bsi['dialnorm2'] = $this->readHeaderBSI(5);
$thisfile_ac3_raw_bsi['flags']['compr2'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['compr2']) {
$thisfile_ac3_raw_bsi['compr2'] = $this->readHeaderBSI(8);
}
}
if ($thisfile_ac3_raw_bsi['strmtyp'] == 1) { // if dependent stream
$thisfile_ac3_raw_bsi['flags']['chanmap'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['chanmap']) {
$thisfile_ac3_raw_bsi['chanmap'] = $this->readHeaderBSI(8);
}
}
$thisfile_ac3_raw_bsi['flags']['mixmdat'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['mixmdat']) { // Mixing metadata
if ($thisfile_ac3_raw_bsi['acmod'] > 2) { // if more than 2 channels
$thisfile_ac3_raw_bsi['dmixmod'] = $this->readHeaderBSI(2);
}
if (($thisfile_ac3_raw_bsi['acmod'] & 0x01) && ($thisfile_ac3_raw_bsi['acmod'] > 2)) { // if three front channels exist
$thisfile_ac3_raw_bsi['ltrtcmixlev'] = $this->readHeaderBSI(3);
$thisfile_ac3_raw_bsi['lorocmixlev'] = $this->readHeaderBSI(3);
}
if ($thisfile_ac3_raw_bsi['acmod'] & 0x04) { // if a surround channel exists
$thisfile_ac3_raw_bsi['ltrtsurmixlev'] = $this->readHeaderBSI(3);
$thisfile_ac3_raw_bsi['lorosurmixlev'] = $this->readHeaderBSI(3);
}
if ($thisfile_ac3_raw_bsi['flags']['lfeon']) { // if the LFE channel exists
$thisfile_ac3_raw_bsi['flags']['lfemixlevcod'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['lfemixlevcod']) {
$thisfile_ac3_raw_bsi['lfemixlevcod'] = $this->readHeaderBSI(5);
}
}
if ($thisfile_ac3_raw_bsi['strmtyp'] == 0) { // if independent stream
$thisfile_ac3_raw_bsi['flags']['pgmscl'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['pgmscl']) {
$thisfile_ac3_raw_bsi['pgmscl'] = $this->readHeaderBSI(6);
}
if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value)
$thisfile_ac3_raw_bsi['flags']['pgmscl2'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['pgmscl2']) {
$thisfile_ac3_raw_bsi['pgmscl2'] = $this->readHeaderBSI(6);
}
}
$thisfile_ac3_raw_bsi['flags']['extpgmscl'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['extpgmscl']) {
$thisfile_ac3_raw_bsi['extpgmscl'] = $this->readHeaderBSI(6);
}
$thisfile_ac3_raw_bsi['mixdef'] = $this->readHeaderBSI(2);
if ($thisfile_ac3_raw_bsi['mixdef'] == 1) { // mixing option 2
$thisfile_ac3_raw_bsi['premixcmpsel'] = (bool) $this->readHeaderBSI(1);
$thisfile_ac3_raw_bsi['drcsrc'] = (bool) $this->readHeaderBSI(1);
$thisfile_ac3_raw_bsi['premixcmpscl'] = $this->readHeaderBSI(3);
} elseif ($thisfile_ac3_raw_bsi['mixdef'] == 2) { // mixing option 3
$thisfile_ac3_raw_bsi['mixdata'] = $this->readHeaderBSI(12);
} elseif ($thisfile_ac3_raw_bsi['mixdef'] == 3) { // mixing option 4
$mixdefbitsread = 0;
$thisfile_ac3_raw_bsi['mixdeflen'] = $this->readHeaderBSI(5); $mixdefbitsread += 5;
$thisfile_ac3_raw_bsi['flags']['mixdata2'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
if ($thisfile_ac3_raw_bsi['flags']['mixdata2']) {
$thisfile_ac3_raw_bsi['premixcmpsel'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
$thisfile_ac3_raw_bsi['drcsrc'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
$thisfile_ac3_raw_bsi['premixcmpscl'] = $this->readHeaderBSI(3); $mixdefbitsread += 3;
$thisfile_ac3_raw_bsi['flags']['extpgmlscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
if ($thisfile_ac3_raw_bsi['flags']['extpgmlscl']) {
$thisfile_ac3_raw_bsi['extpgmlscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
}
$thisfile_ac3_raw_bsi['flags']['extpgmcscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
if ($thisfile_ac3_raw_bsi['flags']['extpgmcscl']) {
$thisfile_ac3_raw_bsi['extpgmcscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
}
$thisfile_ac3_raw_bsi['flags']['extpgmrscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
if ($thisfile_ac3_raw_bsi['flags']['extpgmrscl']) {
$thisfile_ac3_raw_bsi['extpgmrscl'] = $this->readHeaderBSI(4);
}
$thisfile_ac3_raw_bsi['flags']['extpgmlsscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
if ($thisfile_ac3_raw_bsi['flags']['extpgmlsscl']) {
$thisfile_ac3_raw_bsi['extpgmlsscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
}
$thisfile_ac3_raw_bsi['flags']['extpgmrsscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
if ($thisfile_ac3_raw_bsi['flags']['extpgmrsscl']) {
$thisfile_ac3_raw_bsi['extpgmrsscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
}
$thisfile_ac3_raw_bsi['flags']['extpgmlfescl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
if ($thisfile_ac3_raw_bsi['flags']['extpgmlfescl']) {
$thisfile_ac3_raw_bsi['extpgmlfescl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
}
$thisfile_ac3_raw_bsi['flags']['dmixscl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
if ($thisfile_ac3_raw_bsi['flags']['dmixscl']) {
$thisfile_ac3_raw_bsi['dmixscl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
}
$thisfile_ac3_raw_bsi['flags']['addch'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
if ($thisfile_ac3_raw_bsi['flags']['addch']) {
$thisfile_ac3_raw_bsi['flags']['extpgmaux1scl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
if ($thisfile_ac3_raw_bsi['flags']['extpgmaux1scl']) {
$thisfile_ac3_raw_bsi['extpgmaux1scl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
}
$thisfile_ac3_raw_bsi['flags']['extpgmaux2scl'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
if ($thisfile_ac3_raw_bsi['flags']['extpgmaux2scl']) {
$thisfile_ac3_raw_bsi['extpgmaux2scl'] = $this->readHeaderBSI(4); $mixdefbitsread += 4;
}
}
}
$thisfile_ac3_raw_bsi['flags']['mixdata3'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
if ($thisfile_ac3_raw_bsi['flags']['mixdata3']) {
$thisfile_ac3_raw_bsi['spchdat'] = $this->readHeaderBSI(5); $mixdefbitsread += 5;
$thisfile_ac3_raw_bsi['flags']['addspchdat'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
if ($thisfile_ac3_raw_bsi['flags']['addspchdat']) {
$thisfile_ac3_raw_bsi['spchdat1'] = $this->readHeaderBSI(5); $mixdefbitsread += 5;
$thisfile_ac3_raw_bsi['spchan1att'] = $this->readHeaderBSI(2); $mixdefbitsread += 2;
$thisfile_ac3_raw_bsi['flags']['addspchdat1'] = (bool) $this->readHeaderBSI(1); $mixdefbitsread += 1;
if ($thisfile_ac3_raw_bsi['flags']['addspchdat1']) {
$thisfile_ac3_raw_bsi['spchdat2'] = $this->readHeaderBSI(5); $mixdefbitsread += 5;
$thisfile_ac3_raw_bsi['spchan2att'] = $this->readHeaderBSI(3); $mixdefbitsread += 3;
}
}
}
$mixdata_bits = (8 * ($thisfile_ac3_raw_bsi['mixdeflen'] + 2)) - $mixdefbitsread;
$mixdata_fill = (($mixdata_bits % 8) ? 8 - ($mixdata_bits % 8) : 0);
$thisfile_ac3_raw_bsi['mixdata'] = $this->readHeaderBSI($mixdata_bits);
$thisfile_ac3_raw_bsi['mixdatafill'] = $this->readHeaderBSI($mixdata_fill);
unset($mixdefbitsread, $mixdata_bits, $mixdata_fill);
}
if ($thisfile_ac3_raw_bsi['acmod'] < 2) { // if mono or dual mono source
$thisfile_ac3_raw_bsi['flags']['paninfo'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['paninfo']) {
$thisfile_ac3_raw_bsi['panmean'] = $this->readHeaderBSI(8);
$thisfile_ac3_raw_bsi['paninfo'] = $this->readHeaderBSI(6);
}
if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value)
$thisfile_ac3_raw_bsi['flags']['paninfo2'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['paninfo2']) {
$thisfile_ac3_raw_bsi['panmean2'] = $this->readHeaderBSI(8);
$thisfile_ac3_raw_bsi['paninfo2'] = $this->readHeaderBSI(6);
}
}
}
$thisfile_ac3_raw_bsi['flags']['frmmixcfginfo'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['frmmixcfginfo']) { // mixing configuration information
if ($thisfile_ac3_raw_bsi['numblkscod'] == 0) {
$thisfile_ac3_raw_bsi['blkmixcfginfo'][0] = $this->readHeaderBSI(5);
} else {
for ($blk = 0; $blk < $thisfile_ac3_raw_bsi['numblkscod']; $blk++) {
$thisfile_ac3_raw_bsi['flags']['blkmixcfginfo'.$blk] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['blkmixcfginfo'.$blk]) { // mixing configuration information
$thisfile_ac3_raw_bsi['blkmixcfginfo'][$blk] = $this->readHeaderBSI(5);
}
}
}
}
}
}
$thisfile_ac3_raw_bsi['flags']['infomdat'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['infomdat']) { // Informational metadata
$thisfile_ac3_raw_bsi['bsmod'] = $this->readHeaderBSI(3);
$thisfile_ac3_raw_bsi['flags']['copyrightb'] = (bool) $this->readHeaderBSI(1);
$thisfile_ac3_raw_bsi['flags']['origbs'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['acmod'] == 2) { // if in 2/0 mode
$thisfile_ac3_raw_bsi['dsurmod'] = $this->readHeaderBSI(2);
$thisfile_ac3_raw_bsi['dheadphonmod'] = $this->readHeaderBSI(2);
}
if ($thisfile_ac3_raw_bsi['acmod'] >= 6) { // if both surround channels exist
$thisfile_ac3_raw_bsi['dsurexmod'] = $this->readHeaderBSI(2);
}
$thisfile_ac3_raw_bsi['flags']['audprodi'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['audprodi']) {
$thisfile_ac3_raw_bsi['mixlevel'] = $this->readHeaderBSI(5);
$thisfile_ac3_raw_bsi['roomtyp'] = $this->readHeaderBSI(2);
$thisfile_ac3_raw_bsi['flags']['adconvtyp'] = (bool) $this->readHeaderBSI(1);
}
if ($thisfile_ac3_raw_bsi['acmod'] == 0) { // if 1+1 mode (dual mono, so some items need a second value)
$thisfile_ac3_raw_bsi['flags']['audprodi2'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['audprodi2']) {
$thisfile_ac3_raw_bsi['mixlevel2'] = $this->readHeaderBSI(5);
$thisfile_ac3_raw_bsi['roomtyp2'] = $this->readHeaderBSI(2);
$thisfile_ac3_raw_bsi['flags']['adconvtyp2'] = (bool) $this->readHeaderBSI(1);
}
}
if ($thisfile_ac3_raw_bsi['fscod'] < 3) { // if not half sample rate
$thisfile_ac3_raw_bsi['flags']['sourcefscod'] = (bool) $this->readHeaderBSI(1);
}
}
if (($thisfile_ac3_raw_bsi['strmtyp'] == 0) && ($thisfile_ac3_raw_bsi['numblkscod'] != 3)) { // if both surround channels exist
$thisfile_ac3_raw_bsi['flags']['convsync'] = (bool) $this->readHeaderBSI(1);
}
if ($thisfile_ac3_raw_bsi['strmtyp'] == 2) { // if bit stream converted from AC-3
if ($thisfile_ac3_raw_bsi['numblkscod'] != 3) { // 6 blocks per syncframe
$thisfile_ac3_raw_bsi['flags']['blkid'] = 1;
} else {
$thisfile_ac3_raw_bsi['flags']['blkid'] = (bool) $this->readHeaderBSI(1);
}
if ($thisfile_ac3_raw_bsi['flags']['blkid']) {
$thisfile_ac3_raw_bsi['frmsizecod'] = $this->readHeaderBSI(6);
}
}
$thisfile_ac3_raw_bsi['flags']['addbsi'] = (bool) $this->readHeaderBSI(1);
if ($thisfile_ac3_raw_bsi['flags']['addbsi']) {
$thisfile_ac3_raw_bsi['addbsil'] = $this->readHeaderBSI(6);
$thisfile_ac3_raw_bsi['addbsi'] = $this->readHeaderBSI(($thisfile_ac3_raw_bsi['addbsil'] + 1) * 8);
}
} else {
$this->error('Bit stream identification is version '.$thisfile_ac3_raw_bsi['bsid'].', but getID3() only understands up to version 16. Please submit a support ticket with a sample file.');
unset($info['ac3']);
return false;
}
if (isset($thisfile_ac3_raw_bsi['fscod2'])) {
$thisfile_ac3['sample_rate'] = self::sampleRateCodeLookup2($thisfile_ac3_raw_bsi['fscod2']);
} else {
$thisfile_ac3['sample_rate'] = self::sampleRateCodeLookup($thisfile_ac3_raw_bsi['fscod']);
}
if ($thisfile_ac3_raw_bsi['fscod'] <= 3) {
$info['audio']['sample_rate'] = $thisfile_ac3['sample_rate'];
} else {
$this->warning('Unexpected ac3.bsi.fscod value: '.$thisfile_ac3_raw_bsi['fscod']);
}
if (isset($thisfile_ac3_raw_bsi['frmsizecod'])) {
$thisfile_ac3['frame_length'] = self::frameSizeLookup($thisfile_ac3_raw_bsi['frmsizecod'], $thisfile_ac3_raw_bsi['fscod']);
$thisfile_ac3['bitrate'] = self::bitrateLookup($thisfile_ac3_raw_bsi['frmsizecod']);
} elseif (!empty($thisfile_ac3_raw_bsi['frmsiz'])) {
// this isn't right, but it's (usually) close, roughly 5% less than it should be.
// but WHERE is the actual bitrate value stored in EAC3?? email info@getid3.org if you know!
$thisfile_ac3['bitrate'] = ($thisfile_ac3_raw_bsi['frmsiz'] + 1) * 16 * 30; // The frmsiz field shall contain a value one less than the overall size of the coded syncframe in 16-bit words. That is, this field may assume a value ranging from 0 to 2047, and these values correspond to syncframe sizes ranging from 1 to 2048.
// kludge-fix to make it approximately the expected value, still not "right":
$thisfile_ac3['bitrate'] = round(($thisfile_ac3['bitrate'] * 1.05) / 16000) * 16000;
}
$info['audio']['bitrate'] = $thisfile_ac3['bitrate'];
$thisfile_ac3['service_type'] = self::serviceTypeLookup($thisfile_ac3_raw_bsi['bsmod'], $thisfile_ac3_raw_bsi['acmod']);
$ac3_coding_mode = self::audioCodingModeLookup($thisfile_ac3_raw_bsi['acmod']);
foreach($ac3_coding_mode as $key => $value) {
$thisfile_ac3[$key] = $value;
}
switch ($thisfile_ac3_raw_bsi['acmod']) {
case 0:
case 1:
$info['audio']['channelmode'] = 'mono';
break;
case 3:
case 4:
$info['audio']['channelmode'] = 'stereo';
break;
default:
$info['audio']['channelmode'] = 'surround';
break;
}
$info['audio']['channels'] = $thisfile_ac3['num_channels'];
$thisfile_ac3['lfe_enabled'] = $thisfile_ac3_raw_bsi['flags']['lfeon'];
if ($thisfile_ac3_raw_bsi['flags']['lfeon']) {
$info['audio']['channels'] .= '.1';
}
$thisfile_ac3['channels_enabled'] = self::channelsEnabledLookup($thisfile_ac3_raw_bsi['acmod'], $thisfile_ac3_raw_bsi['flags']['lfeon']);
$thisfile_ac3['dialogue_normalization'] = '-'.$thisfile_ac3_raw_bsi['dialnorm'].'dB';
return true;
}
private function readHeaderBSI($length) {
$data = substr($this->AC3header['bsi'], $this->BSIoffset, $length);
$this->BSIoffset += $length;
return bindec($data);
}
public static function sampleRateCodeLookup($fscod) {
static $sampleRateCodeLookup = array(
0 => 48000,
1 => 44100,
2 => 32000,
3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute.
);
return (isset($sampleRateCodeLookup[$fscod]) ? $sampleRateCodeLookup[$fscod] : false);
}
public static function sampleRateCodeLookup2($fscod2) {
static $sampleRateCodeLookup2 = array(
0 => 24000,
1 => 22050,
2 => 16000,
3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute.
);
return (isset($sampleRateCodeLookup2[$fscod2]) ? $sampleRateCodeLookup2[$fscod2] : false);
}
public static function serviceTypeLookup($bsmod, $acmod) {
static $serviceTypeLookup = array();
if (empty($serviceTypeLookup)) {
for ($i = 0; $i <= 7; $i++) {
$serviceTypeLookup[0][$i] = 'main audio service: complete main (CM)';
$serviceTypeLookup[1][$i] = 'main audio service: music and effects (ME)';
$serviceTypeLookup[2][$i] = 'associated service: visually impaired (VI)';
$serviceTypeLookup[3][$i] = 'associated service: hearing impaired (HI)';
$serviceTypeLookup[4][$i] = 'associated service: dialogue (D)';
$serviceTypeLookup[5][$i] = 'associated service: commentary (C)';
$serviceTypeLookup[6][$i] = 'associated service: emergency (E)';
}
$serviceTypeLookup[7][1] = 'associated service: voice over (VO)';
for ($i = 2; $i <= 7; $i++) {
$serviceTypeLookup[7][$i] = 'main audio service: karaoke';
}
}
return (isset($serviceTypeLookup[$bsmod][$acmod]) ? $serviceTypeLookup[$bsmod][$acmod] : false);
}
public static function audioCodingModeLookup($acmod) {
// array(channel configuration, # channels (not incl LFE), channel order)
static $audioCodingModeLookup = array (
0 => array('channel_config'=>'1+1', 'num_channels'=>2, 'channel_order'=>'Ch1,Ch2'),
1 => array('channel_config'=>'1/0', 'num_channels'=>1, 'channel_order'=>'C'),
2 => array('channel_config'=>'2/0', 'num_channels'=>2, 'channel_order'=>'L,R'),
3 => array('channel_config'=>'3/0', 'num_channels'=>3, 'channel_order'=>'L,C,R'),
4 => array('channel_config'=>'2/1', 'num_channels'=>3, 'channel_order'=>'L,R,S'),
5 => array('channel_config'=>'3/1', 'num_channels'=>4, 'channel_order'=>'L,C,R,S'),
6 => array('channel_config'=>'2/2', 'num_channels'=>4, 'channel_order'=>'L,R,SL,SR'),
7 => array('channel_config'=>'3/2', 'num_channels'=>5, 'channel_order'=>'L,C,R,SL,SR'),
);
return (isset($audioCodingModeLookup[$acmod]) ? $audioCodingModeLookup[$acmod] : false);
}
public static function centerMixLevelLookup($cmixlev) {
static $centerMixLevelLookup;
if (empty($centerMixLevelLookup)) {
$centerMixLevelLookup = array(
0 => pow(2, -3.0 / 6), // 0.707 (-3.0 dB)
1 => pow(2, -4.5 / 6), // 0.595 (-4.5 dB)
2 => pow(2, -6.0 / 6), // 0.500 (-6.0 dB)
3 => 'reserved'
);
}
return (isset($centerMixLevelLookup[$cmixlev]) ? $centerMixLevelLookup[$cmixlev] : false);
}
public static function surroundMixLevelLookup($surmixlev) {
static $surroundMixLevelLookup;
if (empty($surroundMixLevelLookup)) {
$surroundMixLevelLookup = array(
0 => pow(2, -3.0 / 6),
1 => pow(2, -6.0 / 6),
2 => 0,
3 => 'reserved'
);
}
return (isset($surroundMixLevelLookup[$surmixlev]) ? $surroundMixLevelLookup[$surmixlev] : false);
}
public static function dolbySurroundModeLookup($dsurmod) {
static $dolbySurroundModeLookup = array(
0 => 'not indicated',
1 => 'Not Dolby Surround encoded',
2 => 'Dolby Surround encoded',
3 => 'reserved'
);
return (isset($dolbySurroundModeLookup[$dsurmod]) ? $dolbySurroundModeLookup[$dsurmod] : false);
}
public static function channelsEnabledLookup($acmod, $lfeon) {
$lookup = array(
'ch1'=>(bool) ($acmod == 0),
'ch2'=>(bool) ($acmod == 0),
'left'=>(bool) ($acmod > 1),
'right'=>(bool) ($acmod > 1),
'center'=>(bool) ($acmod & 0x01),
'surround_mono'=>false,
'surround_left'=>false,
'surround_right'=>false,
'lfe'=>$lfeon);
switch ($acmod) {
case 4:
case 5:
$lookup['surround_mono'] = true;
break;
case 6:
case 7:
$lookup['surround_left'] = true;
$lookup['surround_right'] = true;
break;
}
return $lookup;
}
public static function heavyCompression($compre) {
// The first four bits indicate gain changes in 6.02dB increments which can be
// implemented with an arithmetic shift operation. The following four bits
// indicate linear gain changes, and require a 5-bit multiply.
// We will represent the two 4-bit fields of compr as follows:
// X0 X1 X2 X3 . Y4 Y5 Y6 Y7
// The meaning of the X values is most simply described by considering X to represent a 4-bit
// signed integer with values from -8 to +7. The gain indicated by X is then (X + 1) * 6.02 dB. The
// following table shows this in detail.
// Meaning of 4 msb of compr
// 7 +48.16 dB
// 6 +42.14 dB
// 5 +36.12 dB
// 4 +30.10 dB
// 3 +24.08 dB
// 2 +18.06 dB
// 1 +12.04 dB
// 0 +6.02 dB
// -1 0 dB
// -2 -6.02 dB
// -3 -12.04 dB
// -4 -18.06 dB
// -5 -24.08 dB
// -6 -30.10 dB
// -7 -36.12 dB
// -8 -42.14 dB
$fourbit = str_pad(decbin(($compre & 0xF0) >> 4), 4, '0', STR_PAD_LEFT);
if ($fourbit{0} == '1') {
$log_gain = -8 + bindec(substr($fourbit, 1));
} else {
$log_gain = bindec(substr($fourbit, 1));
}
$log_gain = ($log_gain + 1) * getid3_lib::RGADamplitude2dB(2);
// The value of Y is a linear representation of a gain change of up to -6 dB. Y is considered to
// be an unsigned fractional integer, with a leading value of 1, or: 0.1 Y4 Y5 Y6 Y7 (base 2). Y can
// represent values between 0.111112 (or 31/32) and 0.100002 (or 1/2). Thus, Y can represent gain
// changes from -0.28 dB to -6.02 dB.
$lin_gain = (16 + ($compre & 0x0F)) / 32;
// The combination of X and Y values allows compr to indicate gain changes from
// 48.16 - 0.28 = +47.89 dB, to
// -42.14 - 6.02 = -48.16 dB.
return $log_gain - $lin_gain;
}
public static function roomTypeLookup($roomtyp) {
static $roomTypeLookup = array(
0 => 'not indicated',
1 => 'large room, X curve monitor',
2 => 'small room, flat monitor',
3 => 'reserved'
);
return (isset($roomTypeLookup[$roomtyp]) ? $roomTypeLookup[$roomtyp] : false);
}
public static function frameSizeLookup($frmsizecod, $fscod) {
// LSB is whether padding is used or not
$padding = (bool) ($frmsizecod & 0x01);
$framesizeid = ($frmsizecod & 0x3E) >> 1;
static $frameSizeLookup = array();
if (empty($frameSizeLookup)) {
$frameSizeLookup = array (
0 => array( 128, 138, 192), // 32 kbps
1 => array( 160, 174, 240), // 40 kbps
2 => array( 192, 208, 288), // 48 kbps
3 => array( 224, 242, 336), // 56 kbps
4 => array( 256, 278, 384), // 64 kbps
5 => array( 320, 348, 480), // 80 kbps
6 => array( 384, 416, 576), // 96 kbps
7 => array( 448, 486, 672), // 112 kbps
8 => array( 512, 556, 768), // 128 kbps
9 => array( 640, 696, 960), // 160 kbps
10 => array( 768, 834, 1152), // 192 kbps
11 => array( 896, 974, 1344), // 224 kbps
12 => array(1024, 1114, 1536), // 256 kbps
13 => array(1280, 1392, 1920), // 320 kbps
14 => array(1536, 1670, 2304), // 384 kbps
15 => array(1792, 1950, 2688), // 448 kbps
16 => array(2048, 2228, 3072), // 512 kbps
17 => array(2304, 2506, 3456), // 576 kbps
18 => array(2560, 2786, 3840) // 640 kbps
);
}
if (($fscod == 1) && $padding) {
// frame lengths are padded by 1 word (16 bits) at 44100
$frameSizeLookup[$frmsizecod] += 2;
}
return (isset($frameSizeLookup[$framesizeid][$fscod]) ? $frameSizeLookup[$framesizeid][$fscod] : false);
}
public static function bitrateLookup($frmsizecod) {
// LSB is whether padding is used or not
$padding = (bool) ($frmsizecod & 0x01);
$framesizeid = ($frmsizecod & 0x3E) >> 1;
static $bitrateLookup = array(
0 => 32000,
1 => 40000,
2 => 48000,
3 => 56000,
4 => 64000,
5 => 80000,
6 => 96000,
7 => 112000,
8 => 128000,
9 => 160000,
10 => 192000,
11 => 224000,
12 => 256000,
13 => 320000,
14 => 384000,
15 => 448000,
16 => 512000,
17 => 576000,
18 => 640000,
);
return (isset($bitrateLookup[$framesizeid]) ? $bitrateLookup[$framesizeid] : false);
}
public static function blocksPerSyncFrame($numblkscod) {
static $blocksPerSyncFrameLookup = array(
0 => 1,
1 => 2,
2 => 3,
3 => 6,
);
return (isset($blocksPerSyncFrameLookup[$numblkscod]) ? $blocksPerSyncFrameLookup[$numblkscod] : false);
}
}
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