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/home/tahkoom/public_html/wp-includes/ID3/module.audio.ac3.php
<?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.ac3.php                                        //
// module for analyzing AC-3 (aka Dolby Digital) audio files   //
// dependencies: NONE                                          //
//                                                            ///
/////////////////////////////////////////////////////////////////

if (!defined('GETID3_INCLUDEPATH')) { // prevent path-exposing attacks that access modules directly on public webservers
	exit;
}

class getid3_ac3 extends getid3_handler
{
	/**
	 * @var array
	 */
	private $AC3header = array();

	/**
	 * @var int
	 */
	private $BSIoffset = 0;

	const syncword = 0x0B77;

	/**
	 * @return bool
	 */
	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'];

		if (isset($thisfile_ac3_raw_bsi['bsmod']) && isset($thisfile_ac3_raw_bsi['acmod'])) {
			$thisfile_ac3['service_type'] = self::serviceTypeLookup($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;
	}

	/**
	 * @param int $length
	 *
	 * @return int
	 */
	private function readHeaderBSI($length) {
		$data = substr($this->AC3header['bsi'], $this->BSIoffset, $length);
		$this->BSIoffset += $length;

		return bindec($data);
	}

	/**
	 * @param int $fscod
	 *
	 * @return int|string|false
	 */
	public static function sampleRateCodeLookup($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);
	}

	/**
	 * @param int $fscod2
	 *
	 * @return int|string|false
	 */
	public static function sampleRateCodeLookup2($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);
	}

	/**
	 * @param int $bsmod
	 * @param int $acmod
	 *
	 * @return string|false
	 */
	public static function serviceTypeLookup($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);
	}

	/**
	 * @param int $acmod
	 *
	 * @return array|false
	 */
	public static function audioCodingModeLookup($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);
	}

	/**
	 * @param int $cmixlev
	 *
	 * @return int|float|string|false
	 */
	public static function centerMixLevelLookup($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);
	}

	/**
	 * @param int $surmixlev
	 *
	 * @return int|float|string|false
	 */
	public static function surroundMixLevelLookup($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);
	}

	/**
	 * @param int $dsurmod
	 *
	 * @return string|false
	 */
	public static function dolbySurroundModeLookup($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);
	}

	/**
	 * @param int  $acmod
	 * @param bool $lfeon
	 *
	 * @return array
	 */
	public static function channelsEnabledLookup($acmod, $lfeon) {
		$lookup = array(
			'ch1'=>($acmod == 0),
			'ch2'=>($acmod == 0),
			'left'=>($acmod > 1),
			'right'=>($acmod > 1),
			'center'=>(bool) ($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;
	}

	/**
	 * @param int $compre
	 *
	 * @return float|int
	 */
	public static function heavyCompression($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;
	}

	/**
	 * @param int $roomtyp
	 *
	 * @return string|false
	 */
	public static function roomTypeLookup($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);
	}

	/**
	 * @param int $frmsizecod
	 * @param int $fscod
	 *
	 * @return int|false
	 */
	public static function frameSizeLookup($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
			);
		}
		$paddingBytes = 0;
		if (($fscod == 1) && $padding) {
			// frame lengths are padded by 1 word (16 bits) at 44100
			// (fscode==1) means 44100Hz (see sampleRateCodeLookup)
			$paddingBytes = 2;
		}
		return (isset($frameSizeLookup[$framesizeid][$fscod]) ? $frameSizeLookup[$framesizeid][$fscod] + $paddingBytes : false);
	}

	/**
	 * @param int $frmsizecod
	 *
	 * @return int|false
	 */
	public static function bitrateLookup($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);
	}

	/**
	 * @param int $numblkscod
	 *
	 * @return int|false
	 */
	public static function blocksPerSyncFrame($numblkscod) {
		static $blocksPerSyncFrameLookup = array(
			0 => 1,
			1 => 2,
			2 => 3,
			3 => 6,
		);
		return (isset($blocksPerSyncFrameLookup[$numblkscod]) ? $blocksPerSyncFrameLookup[$numblkscod] : false);
	}


}
تكنولوجيا السيارات الذكية تفرض قواعد جديدة علي الطرق – tahkoom.com
خطوة

تكنولوجيا السيارات الذكية تفرض قواعد جديدة علي الطرق

 كتبت ميرنا أشرف

 أحدثت التكنولوجيا تطورا كبيرا في عالم السيارات، أبرزها تطوير الس يارات الكهربائية كحل مستدام للمستقبل. تتميز هذه السيارات بكفاءة عالية، وانبعاثات منخفضة، وتكاليف تشغيل أقل. رغم ذلك، لا تزال تواجه تحديات، ومع الابتكار المستمر تساهم التكنولوجيا في تجاوز هذه العقبات وتوسيع الاعتماد على النقل الكهربائي.

 أكد الأستاذ هاني هشام، مدير إحدي معارض السيارات الكهربائية بالقاهرة، أن معرضة يُعد من المعارض الرائدة في مجال السيارات الكهربائية في مصر، حيث اتخذ خطوة جريئة بافتتاح معرض متخصص بالكامل في السيارات الكهربائية. وأضاف: “خطوتنا جاءت من إيماننا بأن المستقبل في سيارتك، لأن البنزين في طريقه للنهاية”. وأضاف، أن السبب الثاني لاتخاذ هذه الخطوة هو الارتفاع الكبير في تكلفة البنزين، مما يجعل السيارات الكهربائية هي البديل القوي للسيارات التقليدية خلال الفترة القادمة.

 ومن جانبه، أكد الأستاذ مجدي كيلاني، أحد مسؤولي المبيعات لإحدي معارض السيارات بالقاهرة، أن التوجه للسيارات الكهربائية لم يعد رفاهية، بل ضرورة تفرضها المعايير البيئية والاقتصادية الحديثة. وأضاف أن المعرض يسعى لتوفير موديلات متنوعة تناسب احتياجات السوق المصري، مع تقديم خدمات ما بعد البيع وتوفير الدعم الفني اللازم، في خطوة تهدف إلى بناء ثقة المستهلك وتشجيعه على التحول لهذا النوع من السيارات

 مميزات سيارات الكهرباء:

 أوضح هشام، أنه من أبرز مميزات السيارات الكهربائية أنها تعتمد على بطاريات ليثيوم مما يجعل عمرها الافتراضي طويلاً ، ويجعلها أيضاً خيارًا عمليًا واقتصاديًا على المدى البعيد. كما أن قطع غيارها متوفرة، وصيانتها محدودة مقارنة بالسيارات التقليدية، كما أنها تحافظ على البيئة المحيطة بها وتُعد صديقة للبيئة، بفضل خلوّها من الانبعاثات الضارة.

وهناك نظام تمتاز به سيارات الكهرباء ليست في السيارات العادية وهي قدرتها على قراءة إرشادات الطريق الموجودة عليه، والتعرف على اللوحات والإشارات المنتشرة في الشوارع، مما يعزز من أمان القيادة ويسهل على السائقين التنقل بذكاء وسهولة.

 اتفق معه كيلاني، وأضاف أن السيارات الكهربائية تتميز بعدة مزايا تجعلها خيارًا أفضل للمستقبل، أولها نها لا تستهلك البنزين، مما يجعلها وسيلة موفرة بالمقارنة بالسيارات التقليدية المستهلكة للبنزين المستمر.

وتزوّد بعض من انواع سيارات الكهرباء المتقدمة في الطراز بأنظمة أمان ذكية، خاصة في السيارات ذاتية القيادة، فعلى سبيل المثال، إذا وجدت طفلا يقطع الطريق فجأة، تقوم السيارة تلقائيًا بتفعيل وضع منع التصادم والتوقف الفوري، مما يعزز من مستوى الامان على الطرق و علي المستخدم.

  التحديات التي تواجه سيارات الكهرباء :

 قال هشام، إن أولى التحديات التي تواجه انتشار السيارات الكهربائية تتعلق بالعقلية و التفكير، حيث لايزال كثير من الناس غير مقتنعين تمامًا بفكرة الاعتماد على هذا النوع من السيارات، ويشعرون بالتخوف من السير بسيارة تعمل فقط بالبطارية. هذا التخوف يُشكل عامل قلق لدى العديد من الأفراد، نتيجة لعدم الاطمئنان الكامل تجاه مدى أمان البطارية وكفاءتها، وهو ما يتطلب جهود أكبر لنشر الوعي وتوضيح مزايا هذه التكنولوجيا الجديدة.

 بينما يري الكيلاني، ان هناك تحدي واضح يتمثل في غياب المراكز المعتمدة لصيانتها حتى الآن فبالرغم من انها لا تحتاج صيانه في اغلب الاوقات الا انه لا يمكن شراء سيارة بدون معرفه مراكز صيانتها وذلك ايضا هو نوع من تخوف الافراد لشرائها، وذلك يحدث بسبب ضعف البنية التحتية اللازمة لدعم هذا النوع من السيارات بالشكل الكافي.

 وحول مدى تطور التكنولوجيا في مجال السيارات الكهربائية، يرى الأستاذ هشام، أن ما وصلت إليه هذه الصناعة يؤكد انها تمثل المستقبل الحقيقي لعالم السيارات، وان هذا التطور التكنولوجي يسهم في تعزيز ثقة المستهلك ويدعم توجه السوق نحو البدائل النظيفة والمستدامة.

ومن جانبه، أشار الكيلاني، إلي أن هذا التطور يمهد لتحول في قطاع النقل، خاصة على المدى البعيد. وأكد أن انتشار السيارات الكهربائية سيسهم بشكل كبير في تقليل نسبة التلوث الذي يتعرض له الهواء نتيجة الانبعاثات الناتجة عن وقود السيارات التقليدية.

 تمثل السيارات الكهربائية مستقبل النقل الذكي والمستدام، وسط التطور التكنولوجي المتسارع والجهود المستمرة لتجاوز هذه التحديات وبناء ثقة المستهلك نحو بيئة أنظف وقيادة أكثر كفاءة.

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