<?php
/////////////////////////////////////////////////////////////////
/// getID3() by James Heinrich <[email protected]> //
// available at http://getid3.sourceforge.net //
// or http://www.getid3.org //
/////////////////////////////////////////////////////////////////
// See readme.txt for more details //
/////////////////////////////////////////////////////////////////
// //
// module.audio.aac.php //
// module for analyzing AAC Audio files //
// dependencies: NONE //
// ///
/////////////////////////////////////////////////////////////////
class getid3_aac extends getid3_handler
{
function Analyze() {
$info = &$this->getid3->info;
fseek($this->getid3->fp, $info['avdataoffset'], SEEK_SET);
if (fread($this->getid3->fp, 4) == 'ADIF') {
$this->getAACADIFheaderFilepointer();
} else {
$this->getAACADTSheaderFilepointer();
}
return true;
}
function getAACADIFheaderFilepointer() {
$info = &$this->getid3->info;
$info['fileformat'] = 'aac';
$info['audio']['dataformat'] = 'aac';
$info['audio']['lossless'] = false;
fseek($this->getid3->fp, $info['avdataoffset'], SEEK_SET);
$AACheader = fread($this->getid3->fp, 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) {
$info['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']);
$info['error'][] = 'AAC-ADIF synch not found at offset '.$info['avdataoffset'].' (expected "ADIF", found "'.substr($AACheader, 0, 4).'" instead)';
return false;
}
}
function getAACADTSheaderFilepointer($MaxFramesToScan=1000000, $ReturnExtendedInfo=false) {
$info = &$this->getid3->info;
// based loosely on code from AACfile by Jurgen Faul <jfaulШgmx.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)) {
$info['warning'][] = 'Unable to parse AAC file beyond '.ftell($this->getid3->fp).' (PHP does not support file operations beyond '.round(PHP_INT_MAX / 1073741824).'GB)';
return false;
}
fseek($this->getid3->fp, $byteoffset, SEEK_SET);
// First get substring
$substring = fread($this->getid3->fp, 9); // header is 7 bytes (or 9 if CRC is present)
$substringlength = strlen($substring);
if ($substringlength != 9) {
$info['error'][] = 'Failed to read 7 bytes at offset '.(ftell($this->getid3->fp) - $substringlength).' (only read '.$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) {
$info['error'][] = 'Synch pattern (0x0FFF) not found at offset '.(ftell($this->getid3->fp) - $substringlength).' (found 0x0'.strtoupper(dechex($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) {
$info['warning'][] = 'Layer error - expected "0", found "'.$info['aac']['header']['raw']['mpeg_layer'].'" instead';
}
if ($info['aac']['header']['sample_frequency'] == 0) {
$info['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) {
$info['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;
}
}
?>