--- /dev/null
+<?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.aac.php //
+// module for analyzing AAC Audio files //
+// dependencies: NONE //
+// ///
+/////////////////////////////////////////////////////////////////
+
+
+class getid3_aac extends getid3_handler
+{
+ public function Analyze() {
+ $info = &$this->getid3->info;
+ $this->fseek($info['avdataoffset']);
+ if ($this->fread(4) == 'ADIF') {
+ $this->getAACADIFheaderFilepointer();
+ } else {
+ $this->getAACADTSheaderFilepointer();
+ }
+ return true;
+ }
+
+
+
+ public function getAACADIFheaderFilepointer() {
+ $info = &$this->getid3->info;
+ $info['fileformat'] = 'aac';
+ $info['audio']['dataformat'] = 'aac';
+ $info['audio']['lossless'] = false;
+
+ $this->fseek($info['avdataoffset']);
+ $AACheader = $this->fread(1024);
+ $offset = 0;
+
+ if (substr($AACheader, 0, 4) == 'ADIF') {
+
+ // http://faac.sourceforge.net/wiki/index.php?page=ADIF
+
+ // http://libmpeg.org/mpeg4/doc/w2203tfs.pdf
+ // adif_header() {
+ // adif_id 32
+ // copyright_id_present 1
+ // if( copyright_id_present )
+ // copyright_id 72
+ // original_copy 1
+ // home 1
+ // bitstream_type 1
+ // bitrate 23
+ // num_program_config_elements 4
+ // for (i = 0; i < num_program_config_elements + 1; i++ ) {
+ // if( bitstream_type == '0' )
+ // adif_buffer_fullness 20
+ // program_config_element()
+ // }
+ // }
+
+ $AACheaderBitstream = getid3_lib::BigEndian2Bin($AACheader);
+ $bitoffset = 0;
+
+ $info['aac']['header_type'] = 'ADIF';
+ $bitoffset += 32;
+ $info['aac']['header']['mpeg_version'] = 4;
+
+ $info['aac']['header']['copyright'] = (bool) (substr($AACheaderBitstream, $bitoffset, 1) == '1');
+ $bitoffset += 1;
+ if ($info['aac']['header']['copyright']) {
+ $info['aac']['header']['copyright_id'] = getid3_lib::Bin2String(substr($AACheaderBitstream, $bitoffset, 72));
+ $bitoffset += 72;
+ }
+ $info['aac']['header']['original_copy'] = (bool) (substr($AACheaderBitstream, $bitoffset, 1) == '1');
+ $bitoffset += 1;
+ $info['aac']['header']['home'] = (bool) (substr($AACheaderBitstream, $bitoffset, 1) == '1');
+ $bitoffset += 1;
+ $info['aac']['header']['is_vbr'] = (bool) (substr($AACheaderBitstream, $bitoffset, 1) == '1');
+ $bitoffset += 1;
+ if ($info['aac']['header']['is_vbr']) {
+ $info['audio']['bitrate_mode'] = 'vbr';
+ $info['aac']['header']['bitrate_max'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 23));
+ $bitoffset += 23;
+ } else {
+ $info['audio']['bitrate_mode'] = 'cbr';
+ $info['aac']['header']['bitrate'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 23));
+ $bitoffset += 23;
+ $info['audio']['bitrate'] = $info['aac']['header']['bitrate'];
+ }
+ if ($info['audio']['bitrate'] == 0) {
+ $this->error('Corrupt AAC file: bitrate_audio == zero');
+ return false;
+ }
+ $info['aac']['header']['num_program_configs'] = 1 + getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
+ $bitoffset += 4;
+
+ for ($i = 0; $i < $info['aac']['header']['num_program_configs']; $i++) {
+ // http://www.audiocoding.com/wiki/index.php?page=program_config_element
+
+ // buffer_fullness 20
+
+ // element_instance_tag 4
+ // object_type 2
+ // sampling_frequency_index 4
+ // num_front_channel_elements 4
+ // num_side_channel_elements 4
+ // num_back_channel_elements 4
+ // num_lfe_channel_elements 2
+ // num_assoc_data_elements 3
+ // num_valid_cc_elements 4
+ // mono_mixdown_present 1
+ // mono_mixdown_element_number 4 if mono_mixdown_present == 1
+ // stereo_mixdown_present 1
+ // stereo_mixdown_element_number 4 if stereo_mixdown_present == 1
+ // matrix_mixdown_idx_present 1
+ // matrix_mixdown_idx 2 if matrix_mixdown_idx_present == 1
+ // pseudo_surround_enable 1 if matrix_mixdown_idx_present == 1
+ // for (i = 0; i < num_front_channel_elements; i++) {
+ // front_element_is_cpe[i] 1
+ // front_element_tag_select[i] 4
+ // }
+ // for (i = 0; i < num_side_channel_elements; i++) {
+ // side_element_is_cpe[i] 1
+ // side_element_tag_select[i] 4
+ // }
+ // for (i = 0; i < num_back_channel_elements; i++) {
+ // back_element_is_cpe[i] 1
+ // back_element_tag_select[i] 4
+ // }
+ // for (i = 0; i < num_lfe_channel_elements; i++) {
+ // lfe_element_tag_select[i] 4
+ // }
+ // for (i = 0; i < num_assoc_data_elements; i++) {
+ // assoc_data_element_tag_select[i] 4
+ // }
+ // for (i = 0; i < num_valid_cc_elements; i++) {
+ // cc_element_is_ind_sw[i] 1
+ // valid_cc_element_tag_select[i] 4
+ // }
+ // byte_alignment() VAR
+ // comment_field_bytes 8
+ // for (i = 0; i < comment_field_bytes; i++) {
+ // comment_field_data[i] 8
+ // }
+
+ if (!$info['aac']['header']['is_vbr']) {
+ $info['aac']['program_configs'][$i]['buffer_fullness'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 20));
+ $bitoffset += 20;
+ }
+ $info['aac']['program_configs'][$i]['element_instance_tag'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
+ $bitoffset += 4;
+ $info['aac']['program_configs'][$i]['object_type'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
+ $bitoffset += 2;
+ $info['aac']['program_configs'][$i]['sampling_frequency_index'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
+ $bitoffset += 4;
+ $info['aac']['program_configs'][$i]['num_front_channel_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
+ $bitoffset += 4;
+ $info['aac']['program_configs'][$i]['num_side_channel_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
+ $bitoffset += 4;
+ $info['aac']['program_configs'][$i]['num_back_channel_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
+ $bitoffset += 4;
+ $info['aac']['program_configs'][$i]['num_lfe_channel_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
+ $bitoffset += 2;
+ $info['aac']['program_configs'][$i]['num_assoc_data_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 3));
+ $bitoffset += 3;
+ $info['aac']['program_configs'][$i]['num_valid_cc_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
+ $bitoffset += 4;
+ $info['aac']['program_configs'][$i]['mono_mixdown_present'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
+ $bitoffset += 1;
+ if ($info['aac']['program_configs'][$i]['mono_mixdown_present']) {
+ $info['aac']['program_configs'][$i]['mono_mixdown_element_number'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
+ $bitoffset += 4;
+ }
+ $info['aac']['program_configs'][$i]['stereo_mixdown_present'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
+ $bitoffset += 1;
+ if ($info['aac']['program_configs'][$i]['stereo_mixdown_present']) {
+ $info['aac']['program_configs'][$i]['stereo_mixdown_element_number'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
+ $bitoffset += 4;
+ }
+ $info['aac']['program_configs'][$i]['matrix_mixdown_idx_present'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
+ $bitoffset += 1;
+ if ($info['aac']['program_configs'][$i]['matrix_mixdown_idx_present']) {
+ $info['aac']['program_configs'][$i]['matrix_mixdown_idx'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
+ $bitoffset += 2;
+ $info['aac']['program_configs'][$i]['pseudo_surround_enable'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
+ $bitoffset += 1;
+ }
+ for ($j = 0; $j < $info['aac']['program_configs'][$i]['num_front_channel_elements']; $j++) {
+ $info['aac']['program_configs'][$i]['front_element_is_cpe'][$j] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
+ $bitoffset += 1;
+ $info['aac']['program_configs'][$i]['front_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
+ $bitoffset += 4;
+ }
+ for ($j = 0; $j < $info['aac']['program_configs'][$i]['num_side_channel_elements']; $j++) {
+ $info['aac']['program_configs'][$i]['side_element_is_cpe'][$j] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
+ $bitoffset += 1;
+ $info['aac']['program_configs'][$i]['side_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
+ $bitoffset += 4;
+ }
+ for ($j = 0; $j < $info['aac']['program_configs'][$i]['num_back_channel_elements']; $j++) {
+ $info['aac']['program_configs'][$i]['back_element_is_cpe'][$j] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
+ $bitoffset += 1;
+ $info['aac']['program_configs'][$i]['back_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
+ $bitoffset += 4;
+ }
+ for ($j = 0; $j < $info['aac']['program_configs'][$i]['num_lfe_channel_elements']; $j++) {
+ $info['aac']['program_configs'][$i]['lfe_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
+ $bitoffset += 4;
+ }
+ for ($j = 0; $j < $info['aac']['program_configs'][$i]['num_assoc_data_elements']; $j++) {
+ $info['aac']['program_configs'][$i]['assoc_data_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
+ $bitoffset += 4;
+ }
+ for ($j = 0; $j < $info['aac']['program_configs'][$i]['num_valid_cc_elements']; $j++) {
+ $info['aac']['program_configs'][$i]['cc_element_is_ind_sw'][$j] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
+ $bitoffset += 1;
+ $info['aac']['program_configs'][$i]['valid_cc_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
+ $bitoffset += 4;
+ }
+
+ $bitoffset = ceil($bitoffset / 8) * 8;
+
+ $info['aac']['program_configs'][$i]['comment_field_bytes'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 8));
+ $bitoffset += 8;
+ $info['aac']['program_configs'][$i]['comment_field'] = getid3_lib::Bin2String(substr($AACheaderBitstream, $bitoffset, 8 * $info['aac']['program_configs'][$i]['comment_field_bytes']));
+ $bitoffset += 8 * $info['aac']['program_configs'][$i]['comment_field_bytes'];
+
+
+ $info['aac']['header']['profile'] = self::AACprofileLookup($info['aac']['program_configs'][$i]['object_type'], $info['aac']['header']['mpeg_version']);
+ $info['aac']['program_configs'][$i]['sampling_frequency'] = self::AACsampleRateLookup($info['aac']['program_configs'][$i]['sampling_frequency_index']);
+ $info['audio']['sample_rate'] = $info['aac']['program_configs'][$i]['sampling_frequency'];
+ $info['audio']['channels'] = self::AACchannelCountCalculate($info['aac']['program_configs'][$i]);
+ if ($info['aac']['program_configs'][$i]['comment_field']) {
+ $info['aac']['comments'][] = $info['aac']['program_configs'][$i]['comment_field'];
+ }
+ }
+ $info['playtime_seconds'] = (($info['avdataend'] - $info['avdataoffset']) * 8) / $info['audio']['bitrate'];
+
+ $info['audio']['encoder_options'] = $info['aac']['header_type'].' '.$info['aac']['header']['profile'];
+
+
+
+ return true;
+
+ } else {
+
+ unset($info['fileformat']);
+ unset($info['aac']);
+ $this->error('AAC-ADIF synch not found at offset '.$info['avdataoffset'].' (expected "ADIF", found "'.substr($AACheader, 0, 4).'" instead)');
+ return false;
+
+ }
+
+ }
+
+
+ public function getAACADTSheaderFilepointer($MaxFramesToScan=1000000, $ReturnExtendedInfo=false) {
+ $info = &$this->getid3->info;
+
+ // based loosely on code from AACfile by Jurgen Faul <jfaulØgmx.de>
+ // http://jfaul.de/atl or http://j-faul.virtualave.net/atl/atl.html
+
+
+ // http://faac.sourceforge.net/wiki/index.php?page=ADTS // dead link
+ // http://wiki.multimedia.cx/index.php?title=ADTS
+
+ // * ADTS Fixed Header: these don't change from frame to frame
+ // syncword 12 always: '111111111111'
+ // ID 1 0: MPEG-4, 1: MPEG-2
+ // MPEG layer 2 If you send AAC in MPEG-TS, set to 0
+ // protection_absent 1 0: CRC present; 1: no CRC
+ // profile 2 0: AAC Main; 1: AAC LC (Low Complexity); 2: AAC SSR (Scalable Sample Rate); 3: AAC LTP (Long Term Prediction)
+ // sampling_frequency_index 4 15 not allowed
+ // private_bit 1 usually 0
+ // channel_configuration 3
+ // original/copy 1 0: original; 1: copy
+ // home 1 usually 0
+ // emphasis 2 only if ID == 0 (ie MPEG-4) // not present in some documentation?
+
+ // * ADTS Variable Header: these can change from frame to frame
+ // copyright_identification_bit 1
+ // copyright_identification_start 1
+ // aac_frame_length 13 length of the frame including header (in bytes)
+ // adts_buffer_fullness 11 0x7FF indicates VBR
+ // no_raw_data_blocks_in_frame 2
+
+ // * ADTS Error check
+ // crc_check 16 only if protection_absent == 0
+
+ $byteoffset = $info['avdataoffset'];
+ $framenumber = 0;
+
+ // Init bit pattern array
+ static $decbin = array();
+
+ // Populate $bindec
+ for ($i = 0; $i < 256; $i++) {
+ $decbin[chr($i)] = str_pad(decbin($i), 8, '0', STR_PAD_LEFT);
+ }
+
+ // used to calculate bitrate below
+ $BitrateCache = array();
+
+
+ while (true) {
+ // breaks out when end-of-file encountered, or invalid data found,
+ // or MaxFramesToScan frames have been scanned
+
+ if (!getid3_lib::intValueSupported($byteoffset)) {
+ $this->warning('Unable to parse AAC file beyond '.$this->ftell().' (PHP does not support file operations beyond '.round(PHP_INT_MAX / 1073741824).'GB)');
+ return false;
+ }
+ $this->fseek($byteoffset);
+
+ // First get substring
+ $substring = $this->fread(9); // header is 7 bytes (or 9 if CRC is present)
+ $substringlength = strlen($substring);
+ if ($substringlength != 9) {
+ $this->error('Failed to read 7 bytes at offset '.($this->ftell() - $substringlength).' (only read '.$substringlength.' bytes)');
+ return false;
+ }
+ // this would be easier with 64-bit math, but split it up to allow for 32-bit:
+ $header1 = getid3_lib::BigEndian2Int(substr($substring, 0, 2));
+ $header2 = getid3_lib::BigEndian2Int(substr($substring, 2, 4));
+ $header3 = getid3_lib::BigEndian2Int(substr($substring, 6, 1));
+
+ $info['aac']['header']['raw']['syncword'] = ($header1 & 0xFFF0) >> 4;
+ if ($info['aac']['header']['raw']['syncword'] != 0x0FFF) {
+ $this->error('Synch pattern (0x0FFF) not found at offset '.($this->ftell() - $substringlength).' (found 0x0'.strtoupper(dechex($info['aac']['header']['raw']['syncword'])).' instead)');
+ //if ($info['fileformat'] == 'aac') {
+ // return true;
+ //}
+ unset($info['aac']);
+ return false;
+ }
+
+ // Gather info for first frame only - this takes time to do 1000 times!
+ if ($framenumber == 0) {
+ $info['aac']['header_type'] = 'ADTS';
+ $info['fileformat'] = 'aac';
+ $info['audio']['dataformat'] = 'aac';
+
+ $info['aac']['header']['raw']['mpeg_version'] = ($header1 & 0x0008) >> 3;
+ $info['aac']['header']['raw']['mpeg_layer'] = ($header1 & 0x0006) >> 1;
+ $info['aac']['header']['raw']['protection_absent'] = ($header1 & 0x0001) >> 0;
+
+ $info['aac']['header']['raw']['profile_code'] = ($header2 & 0xC0000000) >> 30;
+ $info['aac']['header']['raw']['sample_rate_code'] = ($header2 & 0x3C000000) >> 26;
+ $info['aac']['header']['raw']['private_stream'] = ($header2 & 0x02000000) >> 25;
+ $info['aac']['header']['raw']['channels_code'] = ($header2 & 0x01C00000) >> 22;
+ $info['aac']['header']['raw']['original'] = ($header2 & 0x00200000) >> 21;
+ $info['aac']['header']['raw']['home'] = ($header2 & 0x00100000) >> 20;
+ $info['aac']['header']['raw']['copyright_stream'] = ($header2 & 0x00080000) >> 19;
+ $info['aac']['header']['raw']['copyright_start'] = ($header2 & 0x00040000) >> 18;
+ $info['aac']['header']['raw']['frame_length'] = ($header2 & 0x0003FFE0) >> 5;
+
+ $info['aac']['header']['mpeg_version'] = ($info['aac']['header']['raw']['mpeg_version'] ? 2 : 4);
+ $info['aac']['header']['crc_present'] = ($info['aac']['header']['raw']['protection_absent'] ? false: true);
+ $info['aac']['header']['profile'] = self::AACprofileLookup($info['aac']['header']['raw']['profile_code'], $info['aac']['header']['mpeg_version']);
+ $info['aac']['header']['sample_frequency'] = self::AACsampleRateLookup($info['aac']['header']['raw']['sample_rate_code']);
+ $info['aac']['header']['private'] = (bool) $info['aac']['header']['raw']['private_stream'];
+ $info['aac']['header']['original'] = (bool) $info['aac']['header']['raw']['original'];
+ $info['aac']['header']['home'] = (bool) $info['aac']['header']['raw']['home'];
+ $info['aac']['header']['channels'] = (($info['aac']['header']['raw']['channels_code'] == 7) ? 8 : $info['aac']['header']['raw']['channels_code']);
+ if ($ReturnExtendedInfo) {
+ $info['aac'][$framenumber]['copyright_id_bit'] = (bool) $info['aac']['header']['raw']['copyright_stream'];
+ $info['aac'][$framenumber]['copyright_id_start'] = (bool) $info['aac']['header']['raw']['copyright_start'];
+ }
+
+ if ($info['aac']['header']['raw']['mpeg_layer'] != 0) {
+ $this->warning('Layer error - expected "0", found "'.$info['aac']['header']['raw']['mpeg_layer'].'" instead');
+ }
+ if ($info['aac']['header']['sample_frequency'] == 0) {
+ $this->error('Corrupt AAC file: sample_frequency == zero');
+ return false;
+ }
+
+ $info['audio']['sample_rate'] = $info['aac']['header']['sample_frequency'];
+ $info['audio']['channels'] = $info['aac']['header']['channels'];
+ }
+
+ $FrameLength = ($header2 & 0x0003FFE0) >> 5;
+
+ if (!isset($BitrateCache[$FrameLength])) {
+ $BitrateCache[$FrameLength] = ($info['aac']['header']['sample_frequency'] / 1024) * $FrameLength * 8;
+ }
+ getid3_lib::safe_inc($info['aac']['bitrate_distribution'][$BitrateCache[$FrameLength]], 1);
+
+ $info['aac'][$framenumber]['aac_frame_length'] = $FrameLength;
+
+ $info['aac'][$framenumber]['adts_buffer_fullness'] = (($header2 & 0x0000001F) << 6) & (($header3 & 0xFC) >> 2);
+ if ($info['aac'][$framenumber]['adts_buffer_fullness'] == 0x07FF) {
+ $info['audio']['bitrate_mode'] = 'vbr';
+ } else {
+ $info['audio']['bitrate_mode'] = 'cbr';
+ }
+ $info['aac'][$framenumber]['num_raw_data_blocks'] = (($header3 & 0x03) >> 0);
+
+ if ($info['aac']['header']['crc_present']) {
+ //$info['aac'][$framenumber]['crc'] = getid3_lib::BigEndian2Int(substr($substring, 7, 2);
+ }
+
+ if (!$ReturnExtendedInfo) {
+ unset($info['aac'][$framenumber]);
+ }
+
+ /*
+ $rounded_precision = 5000;
+ $info['aac']['bitrate_distribution_rounded'] = array();
+ foreach ($info['aac']['bitrate_distribution'] as $bitrate => $count) {
+ $rounded_bitrate = round($bitrate / $rounded_precision) * $rounded_precision;
+ getid3_lib::safe_inc($info['aac']['bitrate_distribution_rounded'][$rounded_bitrate], $count);
+ }
+ ksort($info['aac']['bitrate_distribution_rounded']);
+ */
+
+ $byteoffset += $FrameLength;
+ if ((++$framenumber < $MaxFramesToScan) && (($byteoffset + 10) < $info['avdataend'])) {
+
+ // keep scanning
+
+ } else {
+
+ $info['aac']['frames'] = $framenumber;
+ $info['playtime_seconds'] = ($info['avdataend'] / $byteoffset) * (($framenumber * 1024) / $info['aac']['header']['sample_frequency']); // (1 / % of file scanned) * (samples / (samples/sec)) = seconds
+ if ($info['playtime_seconds'] == 0) {
+ $this->error('Corrupt AAC file: playtime_seconds == zero');
+ return false;
+ }
+ $info['audio']['bitrate'] = (($info['avdataend'] - $info['avdataoffset']) * 8) / $info['playtime_seconds'];
+ ksort($info['aac']['bitrate_distribution']);
+
+ $info['audio']['encoder_options'] = $info['aac']['header_type'].' '.$info['aac']['header']['profile'];
+
+ return true;
+
+ }
+ }
+ // should never get here.
+ }
+
+ public static function AACsampleRateLookup($samplerateid) {
+ static $AACsampleRateLookup = array();
+ if (empty($AACsampleRateLookup)) {
+ $AACsampleRateLookup[0] = 96000;
+ $AACsampleRateLookup[1] = 88200;
+ $AACsampleRateLookup[2] = 64000;
+ $AACsampleRateLookup[3] = 48000;
+ $AACsampleRateLookup[4] = 44100;
+ $AACsampleRateLookup[5] = 32000;
+ $AACsampleRateLookup[6] = 24000;
+ $AACsampleRateLookup[7] = 22050;
+ $AACsampleRateLookup[8] = 16000;
+ $AACsampleRateLookup[9] = 12000;
+ $AACsampleRateLookup[10] = 11025;
+ $AACsampleRateLookup[11] = 8000;
+ $AACsampleRateLookup[12] = 0;
+ $AACsampleRateLookup[13] = 0;
+ $AACsampleRateLookup[14] = 0;
+ $AACsampleRateLookup[15] = 0;
+ }
+ return (isset($AACsampleRateLookup[$samplerateid]) ? $AACsampleRateLookup[$samplerateid] : 'invalid');
+ }
+
+ public static function AACprofileLookup($profileid, $mpegversion) {
+ static $AACprofileLookup = array();
+ if (empty($AACprofileLookup)) {
+ $AACprofileLookup[2][0] = 'Main profile';
+ $AACprofileLookup[2][1] = 'Low Complexity profile (LC)';
+ $AACprofileLookup[2][2] = 'Scalable Sample Rate profile (SSR)';
+ $AACprofileLookup[2][3] = '(reserved)';
+ $AACprofileLookup[4][0] = 'AAC_MAIN';
+ $AACprofileLookup[4][1] = 'AAC_LC';
+ $AACprofileLookup[4][2] = 'AAC_SSR';
+ $AACprofileLookup[4][3] = 'AAC_LTP';
+ }
+ return (isset($AACprofileLookup[$mpegversion][$profileid]) ? $AACprofileLookup[$mpegversion][$profileid] : 'invalid');
+ }
+
+ public static function AACchannelCountCalculate($program_configs) {
+ $channels = 0;
+ for ($i = 0; $i < $program_configs['num_front_channel_elements']; $i++) {
+ $channels++;
+ if ($program_configs['front_element_is_cpe'][$i]) {
+ // each front element is channel pair (CPE = Channel Pair Element)
+ $channels++;
+ }
+ }
+ for ($i = 0; $i < $program_configs['num_side_channel_elements']; $i++) {
+ $channels++;
+ if ($program_configs['side_element_is_cpe'][$i]) {
+ // each side element is channel pair (CPE = Channel Pair Element)
+ $channels++;
+ }
+ }
+ for ($i = 0; $i < $program_configs['num_back_channel_elements']; $i++) {
+ $channels++;
+ if ($program_configs['back_element_is_cpe'][$i]) {
+ // each back element is channel pair (CPE = Channel Pair Element)
+ $channels++;
+ }
+ }
+ for ($i = 0; $i < $program_configs['num_lfe_channel_elements']; $i++) {
+ $channels++;
+ }
+ return $channels;
+ }
+
+}
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