diff options
Diffstat (limited to 'extensions/TimedMediaHandler/libs/getid3/module.audio.ac3.php')
-rw-r--r-- | extensions/TimedMediaHandler/libs/getid3/module.audio.ac3.php | 473 |
1 files changed, 473 insertions, 0 deletions
diff --git a/extensions/TimedMediaHandler/libs/getid3/module.audio.ac3.php b/extensions/TimedMediaHandler/libs/getid3/module.audio.ac3.php new file mode 100644 index 00000000..9834feb5 --- /dev/null +++ b/extensions/TimedMediaHandler/libs/getid3/module.audio.ac3.php @@ -0,0 +1,473 @@ +<?php +///////////////////////////////////////////////////////////////// +/// getID3() by James Heinrich <info@getid3.org> // +// available at http://getid3.sourceforge.net // +// or http://www.getid3.org // +///////////////////////////////////////////////////////////////// +// 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 = "\x0B\x77"; + + 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']); + $this->AC3header['syncinfo'] = $this->fread(5); + + if (strpos($this->AC3header['syncinfo'], self::syncword) === 0) { + $thisfile_ac3_raw['synchinfo']['synchword'] = self::syncword; + $offset = 2; + } else { + if (!$this->isDependencyFor('matroska')) { + unset($info['fileformat'], $info['ac3']); + return $this->error('Expecting "'.getid3_lib::PrintHexBytes(self::syncword).'" at offset '.$info['avdataoffset'].', found "'.getid3_lib::PrintHexBytes(substr($this->AC3header['syncinfo'], 0, 2)).'"'); + } + $offset = 0; + $this->fseek(-2, SEEK_CUR); + } + + $info['audio']['dataformat'] = 'ac3'; + $info['audio']['bitrate_mode'] = 'cbr'; + $info['audio']['lossless'] = false; + + $thisfile_ac3_raw['synchinfo']['crc1'] = getid3_lib::LittleEndian2Int(substr($this->AC3header['syncinfo'], $offset, 2)); + $ac3_synchinfo_fscod_frmsizecod = getid3_lib::LittleEndian2Int(substr($this->AC3header['syncinfo'], ($offset + 2), 1)); + $thisfile_ac3_raw['synchinfo']['fscod'] = ($ac3_synchinfo_fscod_frmsizecod & 0xC0) >> 6; + $thisfile_ac3_raw['synchinfo']['frmsizecod'] = ($ac3_synchinfo_fscod_frmsizecod & 0x3F); + + $thisfile_ac3['sample_rate'] = self::sampleRateCodeLookup($thisfile_ac3_raw['synchinfo']['fscod']); + if ($thisfile_ac3_raw['synchinfo']['fscod'] <= 3) { + $info['audio']['sample_rate'] = $thisfile_ac3['sample_rate']; + } + + $thisfile_ac3['frame_length'] = self::frameSizeLookup($thisfile_ac3_raw['synchinfo']['frmsizecod'], $thisfile_ac3_raw['synchinfo']['fscod']); + $thisfile_ac3['bitrate'] = self::bitrateLookup($thisfile_ac3_raw['synchinfo']['frmsizecod']); + $info['audio']['bitrate'] = $thisfile_ac3['bitrate']; + + $this->AC3header['bsi'] = getid3_lib::BigEndian2Bin($this->fread(15)); + $ac3_bsi_offset = 0; + + $thisfile_ac3_raw_bsi['bsid'] = $this->readHeaderBSI(5); + if ($thisfile_ac3_raw_bsi['bsid'] > 8) { + // Decoders which can decode version 8 will thus be able to decode version numbers less than 8. + // If this standard is extended by the addition of additional elements or features, a value of bsid greater than 8 will be used. + // Decoders built to this version of the standard will not be able to decode versions with bsid greater than 8. + $this->error('Bit stream identification is version '.$thisfile_ac3_raw_bsi['bsid'].', but getID3() only understands up to version 8'); + unset($info['ac3']); + return false; + } + + $thisfile_ac3_raw_bsi['bsmod'] = $this->readHeaderBSI(3); + $thisfile_ac3_raw_bsi['acmod'] = $this->readHeaderBSI(3); + + $thisfile_ac3['service_type'] = self::serviceTypeLookup($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'] = $thisfile_ac3['num_channels']; + + if ($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['lfeon'] = (bool) $this->readHeaderBSI(1); + $thisfile_ac3['lfe_enabled'] = $thisfile_ac3_raw_bsi['lfeon']; + if ($thisfile_ac3_raw_bsi['lfeon']) { + //$info['audio']['channels']++; + $info['audio']['channels'] .= '.1'; + } + + $thisfile_ac3['channels_enabled'] = self::channelsEnabledLookup($thisfile_ac3_raw_bsi['acmod'], $thisfile_ac3_raw_bsi['lfeon']); + + // 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); + $thisfile_ac3['dialogue_normalization'] = '-'.$thisfile_ac3_raw_bsi['dialnorm'].'dB'; + + $thisfile_ac3_raw_bsi['compre_flag'] = (bool) $this->readHeaderBSI(1); + if ($thisfile_ac3_raw_bsi['compre_flag']) { + $thisfile_ac3_raw_bsi['compr'] = $this->readHeaderBSI(8); + $thisfile_ac3['heavy_compression'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr']); + } + + $thisfile_ac3_raw_bsi['langcode_flag'] = (bool) $this->readHeaderBSI(1); + if ($thisfile_ac3_raw_bsi['langcode_flag']) { + $thisfile_ac3_raw_bsi['langcod'] = $this->readHeaderBSI(8); + } + + $thisfile_ac3_raw_bsi['audprodie'] = (bool) $this->readHeaderBSI(1); + if ($thisfile_ac3_raw_bsi['audprodie']) { + $thisfile_ac3_raw_bsi['mixlevel'] = $this->readHeaderBSI(5); + $thisfile_ac3_raw_bsi['roomtyp'] = $this->readHeaderBSI(2); + + $thisfile_ac3['mixing_level'] = (80 + $thisfile_ac3_raw_bsi['mixlevel']).'dB'; + $thisfile_ac3['room_type'] = self::roomTypeLookup($thisfile_ac3_raw_bsi['roomtyp']); + } + + if ($thisfile_ac3_raw_bsi['acmod'] == 0x00) { + // If acmod is 0, then two completely independent program channels (dual mono) + // are encoded into the bit stream, and are referenced as Ch1, Ch2. In this case, + // a number of additional items are present in BSI or audblk to fully describe Ch2. + + // 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['dialnorm2'] = $this->readHeaderBSI(5); + $thisfile_ac3['dialogue_normalization2'] = '-'.$thisfile_ac3_raw_bsi['dialnorm2'].'dB'; + + $thisfile_ac3_raw_bsi['compre_flag2'] = (bool) $this->readHeaderBSI(1); + if ($thisfile_ac3_raw_bsi['compre_flag2']) { + $thisfile_ac3_raw_bsi['compr2'] = $this->readHeaderBSI(8); + $thisfile_ac3['heavy_compression2'] = self::heavyCompression($thisfile_ac3_raw_bsi['compr2']); + } + + $thisfile_ac3_raw_bsi['langcode_flag2'] = (bool) $this->readHeaderBSI(1); + if ($thisfile_ac3_raw_bsi['langcode_flag2']) { + $thisfile_ac3_raw_bsi['langcod2'] = $this->readHeaderBSI(8); + } + + $thisfile_ac3_raw_bsi['audprodie2'] = (bool) $this->readHeaderBSI(1); + if ($thisfile_ac3_raw_bsi['audprodie2']) { + $thisfile_ac3_raw_bsi['mixlevel2'] = $this->readHeaderBSI(5); + $thisfile_ac3_raw_bsi['roomtyp2'] = $this->readHeaderBSI(2); + + $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); + + $thisfile_ac3_raw_bsi['original'] = (bool) $this->readHeaderBSI(1); + + $thisfile_ac3_raw_bsi['timecode1_flag'] = (bool) $this->readHeaderBSI(1); + if ($thisfile_ac3_raw_bsi['timecode1_flag']) { + $thisfile_ac3_raw_bsi['timecode1'] = $this->readHeaderBSI(14); + } + + $thisfile_ac3_raw_bsi['timecode2_flag'] = (bool) $this->readHeaderBSI(1); + if ($thisfile_ac3_raw_bsi['timecode2_flag']) { + $thisfile_ac3_raw_bsi['timecode2'] = $this->readHeaderBSI(14); + } + + $thisfile_ac3_raw_bsi['addbsi_flag'] = (bool) $this->readHeaderBSI(1); + if ($thisfile_ac3_raw_bsi['addbsi_flag']) { + $thisfile_ac3_raw_bsi['addbsi_length'] = $this->readHeaderBSI(6); + + $this->AC3header['bsi'] .= getid3_lib::BigEndian2Bin($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 += $thisfile_ac3_raw_bsi['addbsi_length'] * 8; + } + + return true; + } + + private function readHeaderBSI($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 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) { + $padding = (bool) ($frmsizecod % 2); + $framesizeid = floor($frmsizecod / 2); + + static $frameSizeLookup = array(); + if (empty($frameSizeLookup)) { + $frameSizeLookup = array ( + 0 => array(128, 138, 192), + 1 => array(40, 160, 174, 240), + 2 => array(48, 192, 208, 288), + 3 => array(56, 224, 242, 336), + 4 => array(64, 256, 278, 384), + 5 => array(80, 320, 348, 480), + 6 => array(96, 384, 416, 576), + 7 => array(112, 448, 486, 672), + 8 => array(128, 512, 556, 768), + 9 => array(160, 640, 696, 960), + 10 => array(192, 768, 834, 1152), + 11 => array(224, 896, 974, 1344), + 12 => array(256, 1024, 1114, 1536), + 13 => array(320, 1280, 1392, 1920), + 14 => array(384, 1536, 1670, 2304), + 15 => array(448, 1792, 1950, 2688), + 16 => array(512, 2048, 2228, 3072), + 17 => array(576, 2304, 2506, 3456), + 18 => array(640, 2560, 2786, 3840) + ); + } + if (($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) { + $framesizeid = floor($frmsizecod / 2); + + 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); + } + + +} |