rlm@3: | rlm@3: // | Allan Hansen | rlm@3: // +----------------------------------------------------------------------+ rlm@3: // | module.audio.ac3.php | rlm@3: // | Module for analyzing AC-3 (aka Dolby Digital) audio files | rlm@3: // | dependencies: NONE | rlm@3: // +----------------------------------------------------------------------+ rlm@3: // rlm@3: // $Id: module.audio.ac3.php,v 1.3 2006/11/02 10:48:01 ah Exp $ rlm@3: rlm@3: rlm@3: rlm@3: class getid3_ac3 extends getid3_handler rlm@3: { rlm@3: rlm@3: public function Analyze() { rlm@3: rlm@3: $getid3 = $this->getid3; rlm@3: rlm@3: // http://www.atsc.org/standards/a_52a.pdf rlm@3: rlm@3: $getid3->info['fileformat'] = 'ac3'; rlm@3: $getid3->info['audio']['dataformat'] = 'ac3'; rlm@3: $getid3->info['audio']['bitrate_mode'] = 'cbr'; rlm@3: $getid3->info['audio']['lossless'] = false; rlm@3: rlm@3: $getid3->info['ac3']['raw']['bsi'] = array (); rlm@3: $info_ac3 = &$getid3->info['ac3']; rlm@3: $info_ac3_raw = &$info_ac3['raw']; rlm@3: $info_ac3_raw_bsi = &$info_ac3_raw['bsi']; rlm@3: rlm@3: rlm@3: // An AC-3 serial coded audio bit stream is made up of a sequence of synchronization frames rlm@3: // Each synchronization frame contains 6 coded audio blocks (AB), each of which represent 256 rlm@3: // new audio samples per channel. A synchronization information (SI) header at the beginning rlm@3: // of each frame contains information needed to acquire and maintain synchronization. A rlm@3: // bit stream information (BSI) header follows SI, and contains parameters describing the coded rlm@3: // audio service. The coded audio blocks may be followed by an auxiliary data (Aux) field. At the rlm@3: // end of each frame is an error check field that includes a CRC word for error detection. An rlm@3: // additional CRC word is located in the SI header, the use of which, by a decoder, is optional. rlm@3: // rlm@3: // syncinfo() | bsi() | AB0 | AB1 | AB2 | AB3 | AB4 | AB5 | Aux | CRC rlm@3: rlm@3: $this->fseek($getid3->info['avdataoffset'], SEEK_SET); rlm@3: $ac3_header['syncinfo'] = $this->fread(5); rlm@3: $info_ac3_raw['synchinfo']['synchword'] = substr($ac3_header['syncinfo'], 0, 2); rlm@3: rlm@3: if ($info_ac3_raw['synchinfo']['synchword'] != "\x0B\x77") { rlm@3: throw new getid3_exception('Expecting "\x0B\x77" at offset '.$getid3->info['avdataoffset'].', found \x'.strtoupper(dechex($ac3_header['syncinfo']{0})).'\x'.strtoupper(dechex($ac3_header['syncinfo']{1})).' instead'); rlm@3: } rlm@3: rlm@3: rlm@3: // syncinfo() { rlm@3: // syncword 16 rlm@3: // crc1 16 rlm@3: // fscod 2 rlm@3: // frmsizecod 6 rlm@3: // } /* end of syncinfo */ rlm@3: rlm@3: $info_ac3_raw['synchinfo']['crc1'] = getid3_lib::LittleEndian2Int(substr($ac3_header['syncinfo'], 2, 2)); rlm@3: $ac3_synchinfo_fscod_frmsizecod = getid3_lib::LittleEndian2Int(substr($ac3_header['syncinfo'], 4, 1)); rlm@3: $info_ac3_raw['synchinfo']['fscod'] = ($ac3_synchinfo_fscod_frmsizecod & 0xC0) >> 6; rlm@3: $info_ac3_raw['synchinfo']['frmsizecod'] = ($ac3_synchinfo_fscod_frmsizecod & 0x3F); rlm@3: rlm@3: $info_ac3['sample_rate'] = getid3_ac3::AC3sampleRateCodeLookup($info_ac3_raw['synchinfo']['fscod']); rlm@3: if ($info_ac3_raw['synchinfo']['fscod'] <= 3) { rlm@3: $getid3->info['audio']['sample_rate'] = $info_ac3['sample_rate']; rlm@3: } rlm@3: rlm@3: $info_ac3['frame_length'] = getid3_ac3::AC3frameSizeLookup($info_ac3_raw['synchinfo']['frmsizecod'], $info_ac3_raw['synchinfo']['fscod']); rlm@3: $info_ac3['bitrate'] = getid3_ac3::AC3bitrateLookup($info_ac3_raw['synchinfo']['frmsizecod']); rlm@3: $getid3->info['audio']['bitrate'] = $info_ac3['bitrate']; rlm@3: rlm@3: $ac3_header['bsi'] = getid3_lib::BigEndian2Bin($this->fread(15)); rlm@3: rlm@3: $info_ac3_raw_bsi['bsid'] = bindec(substr($ac3_header['bsi'], 0, 5)); rlm@3: if ($info_ac3_raw_bsi['bsid'] > 8) { rlm@3: // Decoders which can decode version 8 will thus be able to decode version numbers less than 8. rlm@3: // If this standard is extended by the addition of additional elements or features, a value of bsid greater than 8 will be used. rlm@3: // Decoders built to this version of the standard will not be able to decode versions with bsid greater than 8. rlm@3: throw new getid3_exception('Bit stream identification is version '.$info_ac3_raw_bsi['bsid'].', but getID3() only understands up to version 8'); rlm@3: } rlm@3: rlm@3: $info_ac3_raw_bsi['bsmod'] = bindec(substr($ac3_header['bsi'], 5, 3)); rlm@3: $info_ac3_raw_bsi['acmod'] = bindec(substr($ac3_header['bsi'], 8, 3)); rlm@3: rlm@3: $info_ac3['service_type'] = getid3_ac3::AC3serviceTypeLookup($info_ac3_raw_bsi['bsmod'], $info_ac3_raw_bsi['acmod']); rlm@3: $ac3_coding_mode = getid3_ac3::AC3audioCodingModeLookup($info_ac3_raw_bsi['acmod']); rlm@3: foreach($ac3_coding_mode as $key => $value) { rlm@3: $info_ac3[$key] = $value; rlm@3: } rlm@3: switch ($info_ac3_raw_bsi['acmod']) { rlm@3: case 0: rlm@3: case 1: rlm@3: $getid3->info['audio']['channelmode'] = 'mono'; rlm@3: break; rlm@3: case 3: rlm@3: case 4: rlm@3: $getid3->info['audio']['channelmode'] = 'stereo'; rlm@3: break; rlm@3: default: rlm@3: $getid3->info['audio']['channelmode'] = 'surround'; rlm@3: break; rlm@3: } rlm@3: $getid3->info['audio']['channels'] = $info_ac3['num_channels']; rlm@3: rlm@3: $offset = 11; rlm@3: rlm@3: if ($info_ac3_raw_bsi['acmod'] & 0x01) { rlm@3: // If the lsb of acmod is a 1, center channel is in use and cmixlev follows in the bit stream. rlm@3: $info_ac3_raw_bsi['cmixlev'] = bindec(substr($ac3_header['bsi'], $offset, 2)); rlm@3: $info_ac3['center_mix_level'] = getid3_ac3::AC3centerMixLevelLookup($info_ac3_raw_bsi['cmixlev']); rlm@3: $offset += 2; rlm@3: } rlm@3: rlm@3: if ($info_ac3_raw_bsi['acmod'] & 0x04) { rlm@3: // If the msb of acmod is a 1, surround channels are in use and surmixlev follows in the bit stream. rlm@3: $info_ac3_raw_bsi['surmixlev'] = bindec(substr($ac3_header['bsi'], $offset, 2)); rlm@3: $info_ac3['surround_mix_level'] = getid3_ac3::AC3surroundMixLevelLookup($info_ac3_raw_bsi['surmixlev']); rlm@3: $offset += 2; rlm@3: } rlm@3: rlm@3: if ($info_ac3_raw_bsi['acmod'] == 0x02) { rlm@3: // When operating in the two channel mode, this 2-bit code indicates whether or not the program has been encoded in Dolby Surround. rlm@3: $info_ac3_raw_bsi['dsurmod'] = bindec(substr($ac3_header['bsi'], $offset, 2)); rlm@3: $info_ac3['dolby_surround_mode'] = getid3_ac3::AC3dolbySurroundModeLookup($info_ac3_raw_bsi['dsurmod']); rlm@3: $offset += 2; rlm@3: } rlm@3: rlm@3: $info_ac3_raw_bsi['lfeon'] = $ac3_header['bsi']{$offset++} == '1'; rlm@3: $info_ac3['lfe_enabled'] = $info_ac3_raw_bsi['lfeon']; rlm@3: if ($info_ac3_raw_bsi['lfeon']) { rlm@3: $getid3->info['audio']['channels'] .= '.1'; rlm@3: } rlm@3: rlm@3: $info_ac3['channels_enabled'] = getid3_ac3::AC3channelsEnabledLookup($info_ac3_raw_bsi['acmod'], $info_ac3_raw_bsi['lfeon']); rlm@3: rlm@3: // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1–31. rlm@3: // 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. rlm@3: $info_ac3_raw_bsi['dialnorm'] = bindec(substr($ac3_header['bsi'], $offset, 5)); rlm@3: $offset += 5; rlm@3: $info_ac3['dialogue_normalization'] = '-'.$info_ac3_raw_bsi['dialnorm'].'dB'; rlm@3: rlm@3: $info_ac3_raw_bsi['compre_flag'] = $ac3_header['bsi']{$offset++} == '1'; rlm@3: if ($info_ac3_raw_bsi['compre_flag']) { rlm@3: $info_ac3_raw_bsi['compr'] = bindec(substr($ac3_header['bsi'], $offset, 8)); rlm@3: $offset += 8; rlm@3: rlm@3: $info_ac3['heavy_compression'] = getid3_ac3::AC3heavyCompression($info_ac3_raw_bsi['compr']); rlm@3: } rlm@3: rlm@3: $info_ac3_raw_bsi['langcode_flag'] = $ac3_header['bsi']{$offset++} == '1'; rlm@3: if ($info_ac3_raw_bsi['langcode_flag']) { rlm@3: $info_ac3_raw_bsi['langcod'] = bindec(substr($ac3_header['bsi'], $offset, 8)); rlm@3: $offset += 8; rlm@3: } rlm@3: rlm@3: $info_ac3_raw_bsi['audprodie'] = $ac3_header['bsi']{$offset++} == '1'; rlm@3: if ($info_ac3_raw_bsi['audprodie']) { rlm@3: $info_ac3_raw_bsi['mixlevel'] = bindec(substr($ac3_header['bsi'], $offset, 5)); rlm@3: $offset += 5; rlm@3: rlm@3: $info_ac3_raw_bsi['roomtyp'] = bindec(substr($ac3_header['bsi'], $offset, 2)); rlm@3: $offset += 2; rlm@3: rlm@3: $info_ac3['mixing_level'] = (80 + $info_ac3_raw_bsi['mixlevel']).'dB'; rlm@3: $info_ac3['room_type'] = getid3_ac3::AC3roomTypeLookup($info_ac3_raw_bsi['roomtyp']); rlm@3: } rlm@3: rlm@3: if ($info_ac3_raw_bsi['acmod'] == 0x00) { rlm@3: // If acmod is 0, then two completely independent program channels (dual mono) rlm@3: // are encoded into the bit stream, and are referenced as Ch1, Ch2. In this case, rlm@3: // a number of additional items are present in BSI or audblk to fully describe Ch2. rlm@3: rlm@3: rlm@3: // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1–31. rlm@3: // 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. rlm@3: $info_ac3_raw_bsi['dialnorm2'] = bindec(substr($ac3_header['bsi'], $offset, 5)); rlm@3: $offset += 5; rlm@3: rlm@3: $info_ac3['dialogue_normalization2'] = '-'.$info_ac3_raw_bsi['dialnorm2'].'dB'; rlm@3: rlm@3: $info_ac3_raw_bsi['compre_flag2'] = $ac3_header['bsi']{$offset++} == '1'; rlm@3: if ($info_ac3_raw_bsi['compre_flag2']) { rlm@3: $info_ac3_raw_bsi['compr2'] = bindec(substr($ac3_header['bsi'], $offset, 8)); rlm@3: $offset += 8; rlm@3: rlm@3: $info_ac3['heavy_compression2'] = getid3_ac3::AC3heavyCompression($info_ac3_raw_bsi['compr2']); rlm@3: } rlm@3: rlm@3: $info_ac3_raw_bsi['langcode_flag2'] = $ac3_header['bsi']{$offset++} == '1'; rlm@3: if ($info_ac3_raw_bsi['langcode_flag2']) { rlm@3: $info_ac3_raw_bsi['langcod2'] = bindec(substr($ac3_header['bsi'], $offset, 8)); rlm@3: $offset += 8; rlm@3: } rlm@3: rlm@3: $info_ac3_raw_bsi['audprodie2'] = $ac3_header['bsi']{$offset++} == '1'; rlm@3: if ($info_ac3_raw_bsi['audprodie2']) { rlm@3: $info_ac3_raw_bsi['mixlevel2'] = bindec(substr($ac3_header['bsi'], $offset, 5)); rlm@3: $offset += 5; rlm@3: rlm@3: $info_ac3_raw_bsi['roomtyp2'] = bindec(substr($ac3_header['bsi'], $offset, 2)); rlm@3: $offset += 2; rlm@3: rlm@3: $info_ac3['mixing_level2'] = (80 + $info_ac3_raw_bsi['mixlevel2']).'dB'; rlm@3: $info_ac3['room_type2'] = getid3_ac3::AC3roomTypeLookup($info_ac3_raw_bsi['roomtyp2']); rlm@3: } rlm@3: rlm@3: } rlm@3: rlm@3: $info_ac3_raw_bsi['copyright'] = $ac3_header['bsi']{$offset++} == '1'; rlm@3: rlm@3: $info_ac3_raw_bsi['original'] = $ac3_header['bsi']{$offset++} == '1'; rlm@3: rlm@3: $info_ac3_raw_bsi['timecode1_flag'] = $ac3_header['bsi']{$offset++} == '1'; rlm@3: if ($info_ac3_raw_bsi['timecode1_flag']) { rlm@3: $info_ac3_raw_bsi['timecode1'] = bindec(substr($ac3_header['bsi'], $offset, 14)); rlm@3: $offset += 14; rlm@3: } rlm@3: rlm@3: $info_ac3_raw_bsi['timecode2_flag'] = $ac3_header['bsi']{$offset++} == '1'; rlm@3: if ($info_ac3_raw_bsi['timecode2_flag']) { rlm@3: $info_ac3_raw_bsi['timecode2'] = bindec(substr($ac3_header['bsi'], $offset, 14)); rlm@3: $offset += 14; rlm@3: } rlm@3: rlm@3: $info_ac3_raw_bsi['addbsi_flag'] = $ac3_header['bsi']{$offset++} == '1'; rlm@3: if ($info_ac3_raw_bsi['addbsi_flag']) { rlm@3: $info_ac3_raw_bsi['addbsi_length'] = bindec(substr($ac3_header['bsi'], $offset, 6)); rlm@3: $offset += 6; rlm@3: rlm@3: $ac3_header['bsi'] .= getid3_lib::BigEndian2Bin($this->fread($info_ac3_raw_bsi['addbsi_length'])); rlm@3: rlm@3: $info_ac3_raw_bsi['addbsi_data'] = substr($ac3_header['bsi'], 119, $info_ac3_raw_bsi['addbsi_length'] * 8); rlm@3: } rlm@3: rlm@3: return true; rlm@3: } rlm@3: rlm@3: rlm@3: rlm@3: public static function AC3sampleRateCodeLookup($fscod) { rlm@3: rlm@3: static $lookup = array ( rlm@3: 0 => 48000, rlm@3: 1 => 44100, rlm@3: 2 => 32000, rlm@3: 3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute. rlm@3: ); rlm@3: return (isset($lookup[$fscod]) ? $lookup[$fscod] : false); rlm@3: } rlm@3: rlm@3: rlm@3: rlm@3: public static function AC3serviceTypeLookup($bsmod, $acmod) { rlm@3: rlm@3: static $lookup = array ( rlm@3: 0 => 'main audio service: complete main (CM)', rlm@3: 1 => 'main audio service: music and effects (ME)', rlm@3: 2 => 'associated service: visually impaired (VI)', rlm@3: 3 => 'associated service: hearing impaired (HI)', rlm@3: 4 => 'associated service: dialogue (D)', rlm@3: 5 => 'associated service: commentary (C)', rlm@3: 6 => 'associated service: emergency (E)', rlm@3: 7 => 'main audio service: karaoke' rlm@3: ); rlm@3: rlm@3: if ($bsmod == 7 && $acmod == 1) { rlm@3: return 'associated service: voice over (VO)'; rlm@3: } rlm@3: rlm@3: return (isset($lookup[$bsmod]) ? $lookup[$bsmod] : false); rlm@3: } rlm@3: rlm@3: rlm@3: rlm@3: public static function AC3audioCodingModeLookup($acmod) { rlm@3: rlm@3: // array (channel configuration, # channels (not incl LFE), channel order) rlm@3: static $lookup = array ( rlm@3: 0 => array ('channel_config'=>'1+1', 'num_channels'=>2, 'channel_order'=>'Ch1,Ch2'), rlm@3: 1 => array ('channel_config'=>'1/0', 'num_channels'=>1, 'channel_order'=>'C'), rlm@3: 2 => array ('channel_config'=>'2/0', 'num_channels'=>2, 'channel_order'=>'L,R'), rlm@3: 3 => array ('channel_config'=>'3/0', 'num_channels'=>3, 'channel_order'=>'L,C,R'), rlm@3: 4 => array ('channel_config'=>'2/1', 'num_channels'=>3, 'channel_order'=>'L,R,S'), rlm@3: 5 => array ('channel_config'=>'3/1', 'num_channels'=>4, 'channel_order'=>'L,C,R,S'), rlm@3: 6 => array ('channel_config'=>'2/2', 'num_channels'=>4, 'channel_order'=>'L,R,SL,SR'), rlm@3: 7 => array ('channel_config'=>'3/2', 'num_channels'=>5, 'channel_order'=>'L,C,R,SL,SR') rlm@3: ); rlm@3: return (isset($lookup[$acmod]) ? $lookup[$acmod] : false); rlm@3: } rlm@3: rlm@3: rlm@3: rlm@3: public static function AC3centerMixLevelLookup($cmixlev) { rlm@3: rlm@3: static $lookup; rlm@3: if (!@$lookup) { rlm@3: $lookup = array ( rlm@3: 0 => pow(2, -3.0 / 6), // 0.707 (–3.0 dB) rlm@3: 1 => pow(2, -4.5 / 6), // 0.595 (–4.5 dB) rlm@3: 2 => pow(2, -6.0 / 6), // 0.500 (–6.0 dB) rlm@3: 3 => 'reserved' rlm@3: ); rlm@3: } rlm@3: return (isset($lookup[$cmixlev]) ? $lookup[$cmixlev] : false); rlm@3: } rlm@3: rlm@3: rlm@3: rlm@3: public static function AC3surroundMixLevelLookup($surmixlev) { rlm@3: rlm@3: static $lookup; rlm@3: if (!@$lookup) { rlm@3: $lookup = array ( rlm@3: 0 => pow(2, -3.0 / 6), rlm@3: 1 => pow(2, -6.0 / 6), rlm@3: 2 => 0, rlm@3: 3 => 'reserved' rlm@3: ); rlm@3: } rlm@3: return (isset($lookup[$surmixlev]) ? $lookup[$surmixlev] : false); rlm@3: } rlm@3: rlm@3: rlm@3: rlm@3: public static function AC3dolbySurroundModeLookup($dsurmod) { rlm@3: rlm@3: static $lookup = array ( rlm@3: 0 => 'not indicated', rlm@3: 1 => 'Not Dolby Surround encoded', rlm@3: 2 => 'Dolby Surround encoded', rlm@3: 3 => 'reserved' rlm@3: ); rlm@3: return (isset($lookup[$dsurmod]) ? $lookup[$dsurmod] : false); rlm@3: } rlm@3: rlm@3: rlm@3: rlm@3: public static function AC3channelsEnabledLookup($acmod, $lfeon) { rlm@3: rlm@3: return array ( rlm@3: 'ch1' => $acmod == 0, rlm@3: 'ch2' => $acmod == 0, rlm@3: 'left' => $acmod > 1, rlm@3: 'right' => $acmod > 1, rlm@3: 'center' => (bool)($acmod & 0x01), rlm@3: 'surround_mono' => $acmod == 4 || $acmod == 5, rlm@3: 'surround_left' => $acmod == 6 || $acmod == 7, rlm@3: 'surround_right' => $acmod == 6 || $acmod == 7, rlm@3: 'lfe' => $lfeon rlm@3: ); rlm@3: } rlm@3: rlm@3: rlm@3: rlm@3: public static function AC3heavyCompression($compre) { rlm@3: rlm@3: // The first four bits indicate gain changes in 6.02dB increments which can be rlm@3: // implemented with an arithmetic shift operation. The following four bits rlm@3: // indicate linear gain changes, and require a 5-bit multiply. rlm@3: // We will represent the two 4-bit fields of compr as follows: rlm@3: // X0 X1 X2 X3 . Y4 Y5 Y6 Y7 rlm@3: // The meaning of the X values is most simply described by considering X to represent a 4-bit rlm@3: // signed integer with values from –8 to +7. The gain indicated by X is then (X + 1) * 6.02 dB. The rlm@3: // following table shows this in detail. rlm@3: rlm@3: // Meaning of 4 msb of compr rlm@3: // 7 +48.16 dB rlm@3: // 6 +42.14 dB rlm@3: // 5 +36.12 dB rlm@3: // 4 +30.10 dB rlm@3: // 3 +24.08 dB rlm@3: // 2 +18.06 dB rlm@3: // 1 +12.04 dB rlm@3: // 0 +6.02 dB rlm@3: // -1 0 dB rlm@3: // -2 –6.02 dB rlm@3: // -3 –12.04 dB rlm@3: // -4 –18.06 dB rlm@3: // -5 –24.08 dB rlm@3: // -6 –30.10 dB rlm@3: // -7 –36.12 dB rlm@3: // -8 –42.14 dB rlm@3: rlm@3: $fourbit = str_pad(decbin(($compre & 0xF0) >> 4), 4, '0', STR_PAD_LEFT); rlm@3: if ($fourbit{0} == '1') { rlm@3: $log_gain = -8 + bindec(substr($fourbit, 1)); rlm@3: } else { rlm@3: $log_gain = bindec(substr($fourbit, 1)); rlm@3: } rlm@3: $log_gain = ($log_gain + 1) * (20 * log10(2)); rlm@3: rlm@3: // The value of Y is a linear representation of a gain change of up to –6 dB. Y is considered to rlm@3: // be an unsigned fractional integer, with a leading value of 1, or: 0.1 Y4 Y5 Y6 Y7 (base 2). Y can rlm@3: // represent values between 0.111112 (or 31/32) and 0.100002 (or 1/2). Thus, Y can represent gain rlm@3: // changes from –0.28 dB to –6.02 dB. rlm@3: rlm@3: $lin_gain = (16 + ($compre & 0x0F)) / 32; rlm@3: rlm@3: // The combination of X and Y values allows compr to indicate gain changes from rlm@3: // 48.16 – 0.28 = +47.89 dB, to rlm@3: // –42.14 – 6.02 = –48.16 dB. rlm@3: rlm@3: return $log_gain - $lin_gain; rlm@3: } rlm@3: rlm@3: rlm@3: rlm@3: public static function AC3roomTypeLookup($roomtyp) { rlm@3: rlm@3: static $lookup = array ( rlm@3: 0 => 'not indicated', rlm@3: 1 => 'large room, X curve monitor', rlm@3: 2 => 'small room, flat monitor', rlm@3: 3 => 'reserved' rlm@3: ); rlm@3: return (isset($lookup[$roomtyp]) ? $lookup[$roomtyp] : false); rlm@3: } rlm@3: rlm@3: rlm@3: rlm@3: public static function AC3frameSizeLookup($frmsizecod, $fscod) { rlm@3: rlm@3: $padding = (bool)($frmsizecod % 2); rlm@3: $frame_size_id = floor($frmsizecod / 2); rlm@3: rlm@3: static $lookup = array ( rlm@3: 0 => array (128, 138, 192), rlm@3: 1 => array (40, 160, 174, 240), rlm@3: 2 => array (48, 192, 208, 288), rlm@3: 3 => array (56, 224, 242, 336), rlm@3: 4 => array (64, 256, 278, 384), rlm@3: 5 => array (80, 320, 348, 480), rlm@3: 6 => array (96, 384, 416, 576), rlm@3: 7 => array (112, 448, 486, 672), rlm@3: 8 => array (128, 512, 556, 768), rlm@3: 9 => array (160, 640, 696, 960), rlm@3: 10 => array (192, 768, 834, 1152), rlm@3: 11 => array (224, 896, 974, 1344), rlm@3: 12 => array (256, 1024, 1114, 1536), rlm@3: 13 => array (320, 1280, 1392, 1920), rlm@3: 14 => array (384, 1536, 1670, 2304), rlm@3: 15 => array (448, 1792, 1950, 2688), rlm@3: 16 => array (512, 2048, 2228, 3072), rlm@3: 17 => array (576, 2304, 2506, 3456), rlm@3: 18 => array (640, 2560, 2786, 3840) rlm@3: ); rlm@3: if (($fscod == 1) && $padding) { rlm@3: // frame lengths are padded by 1 word (16 bits) at 44100 rlm@3: $lookup[$frmsizecod] += 2; rlm@3: } rlm@3: return (isset($lookup[$frame_size_id][$fscod]) ? $lookup[$frame_size_id][$fscod] : false); rlm@3: } rlm@3: rlm@3: rlm@3: rlm@3: public static function AC3bitrateLookup($frmsizecod) { rlm@3: rlm@3: static $lookup = array ( rlm@3: 0 => 32000, rlm@3: 1 => 40000, rlm@3: 2 => 48000, rlm@3: 3 => 56000, rlm@3: 4 => 64000, rlm@3: 5 => 80000, rlm@3: 6 => 96000, rlm@3: 7 => 112000, rlm@3: 8 => 128000, rlm@3: 9 => 160000, rlm@3: 10 => 192000, rlm@3: 11 => 224000, rlm@3: 12 => 256000, rlm@3: 13 => 320000, rlm@3: 14 => 384000, rlm@3: 15 => 448000, rlm@3: 16 => 512000, rlm@3: 17 => 576000, rlm@3: 18 => 640000 rlm@3: ); rlm@3: $frame_size_id = floor($frmsizecod / 2); rlm@3: return (isset($lookup[$frame_size_id]) ? $lookup[$frame_size_id] : false); rlm@3: } rlm@3: rlm@3: } rlm@3: rlm@3: ?>