<?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.aac.php //
// module for analyzing AAC Audio files //
// dependencies: NONE //
// ///
/////////////////////////////////////////////////////////////////
class getid3_aac
{
// new combined constructor
function getid3_aac(&$fd, &$ThisFileInfo, $option) {
if ($option === 'adif') {
$this->getAACADIFheaderFilepointer($fd, $ThisFileInfo);
}
elseif ($option === 'adts') {
$this->getAACADTSheaderFilepointer($fd, $ThisFileInfo);
}
}
function getAACADIFheaderFilepointer(&$fd, &$ThisFileInfo) {
$ThisFileInfo['fileformat'] = 'aac';
$ThisFileInfo['audio']['dataformat'] = 'aac';
$ThisFileInfo['audio']['lossless'] = false;
fseek($fd, $ThisFileInfo['avdataoffset'], SEEK_SET);
$AACheader = fread($fd, 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;
$ThisFileInfo['aac']['header_type'] = 'ADIF';
$bitoffset += 32;
$ThisFileInfo['aac']['header']['mpeg_version'] = 4;
$ThisFileInfo['aac']['header']['copyright'] = (bool) (substr($AACheaderBitstream, $bitoffset, 1) == '1');
$bitoffset += 1;
if ($ThisFileInfo['aac']['header']['copyright']) {
$ThisFileInfo['aac']['header']['copyright_id'] = getid3_lib::Bin2String(substr($AACheaderBitstream, $bitoffset, 72));
$bitoffset += 72;
}
$ThisFileInfo['aac']['header']['original_copy'] = (bool) (substr($AACheaderBitstream, $bitoffset, 1) == '1');
$bitoffset += 1;
$ThisFileInfo['aac']['header']['home'] = (bool) (substr($AACheaderBitstream, $bitoffset, 1) == '1');
$bitoffset += 1;
$ThisFileInfo['aac']['header']['is_vbr'] = (bool) (substr($AACheaderBitstream, $bitoffset, 1) == '1');
$bitoffset += 1;
if ($ThisFileInfo['aac']['header']['is_vbr']) {
$ThisFileInfo['audio']['bitrate_mode'] = 'vbr';
$ThisFileInfo['aac']['header']['bitrate_max'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 23));
$bitoffset += 23;
} else {
$ThisFileInfo['audio']['bitrate_mode'] = 'cbr';
$ThisFileInfo['aac']['header']['bitrate'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 23));
$bitoffset += 23;
$ThisFileInfo['audio']['bitrate'] = $ThisFileInfo['aac']['header']['bitrate'];
}
if ($ThisFileInfo['audio']['bitrate'] == 0) {
$ThisFileInfo['error'][] = 'Corrupt AAC file: bitrate_audio == zero';
return false;
}
$ThisFileInfo['aac']['header']['num_program_configs'] = 1 + getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
$bitoffset += 4;
for ($i = 0; $i < $ThisFileInfo['aac']['header']['num_program_configs']; $i++) {
// http://www.audiocoding.com/wiki/index.php?page=program_config_element
// buffer_fullness 20
// element_instance_tag 4
// object_type 2
// sampling_frequency_index 4
// num_front_channel_elements 4
// num_side_channel_elements 4
// num_back_channel_elements 4
// num_lfe_channel_elements 2
// num_assoc_data_elements 3
// num_valid_cc_elements 4
// mono_mixdown_present 1
// mono_mixdown_element_number 4 if mono_mixdown_present == 1
// stereo_mixdown_present 1
// stereo_mixdown_element_number 4 if stereo_mixdown_present == 1
// matrix_mixdown_idx_present 1
// matrix_mixdown_idx 2 if matrix_mixdown_idx_present == 1
// pseudo_surround_enable 1 if matrix_mixdown_idx_present == 1
// for (i = 0; i < num_front_channel_elements; i++) {
// front_element_is_cpe[i] 1
// front_element_tag_select[i] 4
// }
// for (i = 0; i < num_side_channel_elements; i++) {
// side_element_is_cpe[i] 1
// side_element_tag_select[i] 4
// }
// for (i = 0; i < num_back_channel_elements; i++) {
// back_element_is_cpe[i] 1
// back_element_tag_select[i] 4
// }
// for (i = 0; i < num_lfe_channel_elements; i++) {
// lfe_element_tag_select[i] 4
// }
// for (i = 0; i < num_assoc_data_elements; i++) {
// assoc_data_element_tag_select[i] 4
// }
// for (i = 0; i < num_valid_cc_elements; i++) {
// cc_element_is_ind_sw[i] 1
// valid_cc_element_tag_select[i] 4
// }
// byte_alignment() VAR
// comment_field_bytes 8
// for (i = 0; i < comment_field_bytes; i++) {
// comment_field_data[i] 8
// }
if (!$ThisFileInfo['aac']['header']['is_vbr']) {
$ThisFileInfo['aac']['program_configs'][$i]['buffer_fullness'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 20));
$bitoffset += 20;
}
$ThisFileInfo['aac']['program_configs'][$i]['element_instance_tag'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
$bitoffset += 4;
$ThisFileInfo['aac']['program_configs'][$i]['object_type'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
$bitoffset += 2;
$ThisFileInfo['aac']['program_configs'][$i]['sampling_frequency_index'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
$bitoffset += 4;
$ThisFileInfo['aac']['program_configs'][$i]['num_front_channel_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
$bitoffset += 4;
$ThisFileInfo['aac']['program_configs'][$i]['num_side_channel_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
$bitoffset += 4;
$ThisFileInfo['aac']['program_configs'][$i]['num_back_channel_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
$bitoffset += 4;
$ThisFileInfo['aac']['program_configs'][$i]['num_lfe_channel_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
$bitoffset += 2;
$ThisFileInfo['aac']['program_configs'][$i]['num_assoc_data_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 3));
$bitoffset += 3;
$ThisFileInfo['aac']['program_configs'][$i]['num_valid_cc_elements'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
$bitoffset += 4;
$ThisFileInfo['aac']['program_configs'][$i]['mono_mixdown_present'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
$bitoffset += 1;
if ($ThisFileInfo['aac']['program_configs'][$i]['mono_mixdown_present']) {
$ThisFileInfo['aac']['program_configs'][$i]['mono_mixdown_element_number'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
$bitoffset += 4;
}
$ThisFileInfo['aac']['program_configs'][$i]['stereo_mixdown_present'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
$bitoffset += 1;
if ($ThisFileInfo['aac']['program_configs'][$i]['stereo_mixdown_present']) {
$ThisFileInfo['aac']['program_configs'][$i]['stereo_mixdown_element_number'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
$bitoffset += 4;
}
$ThisFileInfo['aac']['program_configs'][$i]['matrix_mixdown_idx_present'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
$bitoffset += 1;
if ($ThisFileInfo['aac']['program_configs'][$i]['matrix_mixdown_idx_present']) {
$ThisFileInfo['aac']['program_configs'][$i]['matrix_mixdown_idx'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
$bitoffset += 2;
$ThisFileInfo['aac']['program_configs'][$i]['pseudo_surround_enable'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
$bitoffset += 1;
}
for ($j = 0; $j < $ThisFileInfo['aac']['program_configs'][$i]['num_front_channel_elements']; $j++) {
$ThisFileInfo['aac']['program_configs'][$i]['front_element_is_cpe'][$j] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
$bitoffset += 1;
$ThisFileInfo['aac']['program_configs'][$i]['front_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
$bitoffset += 4;
}
for ($j = 0; $j < $ThisFileInfo['aac']['program_configs'][$i]['num_side_channel_elements']; $j++) {
$ThisFileInfo['aac']['program_configs'][$i]['side_element_is_cpe'][$j] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
$bitoffset += 1;
$ThisFileInfo['aac']['program_configs'][$i]['side_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
$bitoffset += 4;
}
for ($j = 0; $j < $ThisFileInfo['aac']['program_configs'][$i]['num_back_channel_elements']; $j++) {
$ThisFileInfo['aac']['program_configs'][$i]['back_element_is_cpe'][$j] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
$bitoffset += 1;
$ThisFileInfo['aac']['program_configs'][$i]['back_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
$bitoffset += 4;
}
for ($j = 0; $j < $ThisFileInfo['aac']['program_configs'][$i]['num_lfe_channel_elements']; $j++) {
$ThisFileInfo['aac']['program_configs'][$i]['lfe_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
$bitoffset += 4;
}
for ($j = 0; $j < $ThisFileInfo['aac']['program_configs'][$i]['num_assoc_data_elements']; $j++) {
$ThisFileInfo['aac']['program_configs'][$i]['assoc_data_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
$bitoffset += 4;
}
for ($j = 0; $j < $ThisFileInfo['aac']['program_configs'][$i]['num_valid_cc_elements']; $j++) {
$ThisFileInfo['aac']['program_configs'][$i]['cc_element_is_ind_sw'][$j] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
$bitoffset += 1;
$ThisFileInfo['aac']['program_configs'][$i]['valid_cc_element_tag_select'][$j] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
$bitoffset += 4;
}
$bitoffset = ceil($bitoffset / 8) * 8;
$ThisFileInfo['aac']['program_configs'][$i]['comment_field_bytes'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 8));
$bitoffset += 8;
$ThisFileInfo['aac']['program_configs'][$i]['comment_field'] = getid3_lib::Bin2String(substr($AACheaderBitstream, $bitoffset, 8 * $ThisFileInfo['aac']['program_configs'][$i]['comment_field_bytes']));
$bitoffset += 8 * $ThisFileInfo['aac']['program_configs'][$i]['comment_field_bytes'];
$ThisFileInfo['aac']['header']['profile_text'] = $this->AACprofileLookup($ThisFileInfo['aac']['program_configs'][$i]['object_type'], $ThisFileInfo['aac']['header']['mpeg_version']);
$ThisFileInfo['aac']['program_configs'][$i]['sampling_frequency'] = $this->AACsampleRateLookup($ThisFileInfo['aac']['program_configs'][$i]['sampling_frequency_index']);
$ThisFileInfo['audio']['sample_rate'] = $ThisFileInfo['aac']['program_configs'][$i]['sampling_frequency'];
$ThisFileInfo['audio']['channels'] = $this->AACchannelCountCalculate($ThisFileInfo['aac']['program_configs'][$i]);
if ($ThisFileInfo['aac']['program_configs'][$i]['comment_field']) {
$ThisFileInfo['aac']['comments'][] = $ThisFileInfo['aac']['program_configs'][$i]['comment_field'];
}
}
$ThisFileInfo['playtime_seconds'] = (($ThisFileInfo['avdataend'] - $ThisFileInfo['avdataoffset']) * 8) / $ThisFileInfo['audio']['bitrate'];
$ThisFileInfo['audio']['encoder_options'] = $ThisFileInfo['aac']['header_type'].' '.$ThisFileInfo['aac']['header']['profile_text'];
return true;
} else {
unset($ThisFileInfo['fileformat']);
unset($ThisFileInfo['aac']);
$ThisFileInfo['error'][] = 'AAC-ADIF synch not found at offset '.$ThisFileInfo['avdataoffset'].' (expected "ADIF", found "'.substr($AACheader, 0, 4).'" instead)';
return false;
}
}
function getAACADTSheaderFilepointer(&$fd, &$ThisFileInfo, $MaxFramesToScan=1000000, $ReturnExtendedInfo=false) {
// based loosely on code from AACfile by Jurgen Faul <jfaul�gmx.de>
// http://jfaul.de/atl or http://j-faul.virtualave.net/atl/atl.html
// http://faac.sourceforge.net/wiki/index.php?page=ADTS
// * ADTS Fixed Header: these don't change from frame to frame
// syncword 12 always: '111111111111'
// ID 1 0: MPEG-4, 1: MPEG-2
// layer 2 always: '00'
// protection_absent 1
// profile 2
// sampling_frequency_index 4
// private_bit 1
// channel_configuration 3
// original/copy 1
// home 1
// emphasis 2 only if ID == 0 (ie MPEG-4)
// * 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 = 0;
$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
$BitrateCache = array();
while (true) {
// breaks out when end-of-file encountered, or invalid data found,
// or MaxFramesToScan frames have been scanned
if ($byteoffset >= pow(2, 31)) {
$ThisFileInfo['warning'][] = 'Unable to parse AAC file beyond '.ftell($fd).' (PHP does not support file operations beyond 2GB)';
return false;
}
fseek($fd, $byteoffset, SEEK_SET);
// First get substring
$substring = fread($fd, 10);
$substringlength = strlen($substring);
if ($substringlength != 10) {
$ThisFileInfo['error'][] = 'Failed to read 10 bytes at offset '.(ftell($fd) - $substringlength).' (only read '.$substringlength.' bytes)';
return false;
}
// Initialise $AACheaderBitstream
$AACheaderBitstream = '';
// Loop thru substring chars
for ($i = 0; $i < 10; $i++) {
$AACheaderBitstream .= $decbin[$substring{$i}];
}
$bitoffset = 0;
$synctest = bindec(substr($AACheaderBitstream, $bitoffset, 12));
$bitoffset += 12;
if ($synctest != 0x0FFF) {
$ThisFileInfo['error'][] = 'Synch pattern (0x0FFF) not found at offset '.(ftell($fd) - 10).' (found 0x0'.strtoupper(dechex($synctest)).' instead)';
if ($ThisFileInfo['fileformat'] == 'aac') {
return true;
}
return false;
}
// Gather info for first frame only - this takes time to do 1000 times!
if ($framenumber > 0) {
if (!$AACheaderBitstream[$bitoffset]) {
// MPEG-4
$bitoffset += 20;
} else {
// MPEG-2
$bitoffset += 18;
}
} else {
$ThisFileInfo['aac']['header_type'] = 'ADTS';
$ThisFileInfo['aac']['header']['synch'] = $synctest;
$ThisFileInfo['fileformat'] = 'aac';
$ThisFileInfo['audio']['dataformat'] = 'aac';
$ThisFileInfo['aac']['header']['mpeg_version'] = ((substr($AACheaderBitstream, $bitoffset, 1) == '0') ? 4 : 2);
$bitoffset += 1;
$ThisFileInfo['aac']['header']['layer'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
$bitoffset += 2;
if ($ThisFileInfo['aac']['header']['layer'] != 0) {
$ThisFileInfo['error'][] = 'Layer error - expected 0x00, found 0x'.dechex($ThisFileInfo['aac']['header']['layer']).' instead';
return false;
}
$ThisFileInfo['aac']['header']['crc_present'] = ((substr($AACheaderBitstream, $bitoffset, 1) == '0') ? true : false);
$bitoffset += 1;
$ThisFileInfo['aac']['header']['profile_id'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
$bitoffset += 2;
$ThisFileInfo['aac']['header']['profile_text'] = $this->AACprofileLookup($ThisFileInfo['aac']['header']['profile_id'], $ThisFileInfo['aac']['header']['mpeg_version']);
$ThisFileInfo['aac']['header']['sample_frequency_index'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 4));
$bitoffset += 4;
$ThisFileInfo['aac']['header']['sample_frequency'] = $this->AACsampleRateLookup($ThisFileInfo['aac']['header']['sample_frequency_index']);
if ($ThisFileInfo['aac']['header']['sample_frequency'] == 0) {
$ThisFileInfo['error'][] = 'Corrupt AAC file: sample_frequency == zero';
return false;
}
$ThisFileInfo['audio']['sample_rate'] = $ThisFileInfo['aac']['header']['sample_frequency'];
$ThisFileInfo['aac']['header']['private'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
$bitoffset += 1;
$ThisFileInfo['aac']['header']['channel_configuration'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 3));
$bitoffset += 3;
$ThisFileInfo['audio']['channels'] = $ThisFileInfo['aac']['header']['channel_configuration'];
$ThisFileInfo['aac']['header']['original'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
$bitoffset += 1;
$ThisFileInfo['aac']['header']['home'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
$bitoffset += 1;
if ($ThisFileInfo['aac']['header']['mpeg_version'] == 4) {
$ThisFileInfo['aac']['header']['emphasis'] = getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 2));
$bitoffset += 2;
}
if ($ReturnExtendedInfo) {
$ThisFileInfo['aac'][$framenumber]['copyright_id_bit'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
$bitoffset += 1;
$ThisFileInfo['aac'][$framenumber]['copyright_id_start'] = (bool) getid3_lib::Bin2Dec(substr($AACheaderBitstream, $bitoffset, 1));
$bitoffset += 1;
} else {
$bitoffset += 2;
}
}
$FrameLength = bindec(substr($AACheaderBitstream, $bitoffset, 13));
if (!isset($BitrateCache[$FrameLength])) {
$BitrateCache[$FrameLength] = ($ThisFileInfo['aac']['header']['sample_frequency'] / 1024) * $FrameLength * 8;
}
@$ThisFileInfo['aac']['bitrate_distribution'][$BitrateCache[$FrameLength]]++;
$ThisFileInfo['aac'][$framenumber]['aac_frame_length'] = $FrameLength;
$bitoffset += 13;
$ThisFileInfo['aac'][$framenumber]['adts_buffer_fullness'] = bindec(substr($AACheaderBitstream, $bitoffset, 11));
$bitoffset += 11;
if ($ThisFileInfo['aac'][$framenumber]['adts_buffer_fullness'] == 0x07FF) {
$ThisFileInfo['audio']['bitrate_mode'] = 'vbr';
} else {
$ThisFileInfo['audio']['bitrate_mode'] = 'cbr';
}
$ThisFileInfo['aac'][$framenumber]['num_raw_data_blocks'] = bindec(substr($AACheaderBitstream, $bitoffset, 2));
$bitoffset += 2;
if ($ThisFileInfo['aac']['header']['crc_present']) {
//$ThisFileInfo['aac'][$framenumber]['crc'] = bindec(substr($AACheaderBitstream, $bitoffset, 16));
$bitoffset += 16;
}
if (!$ReturnExtendedInfo) {
unset($ThisFileInfo['aac'][$framenumber]);
}
$byteoffset += $FrameLength;
if ((++$framenumber < $MaxFramesToScan) && (($byteoffset + 10) < $ThisFileInfo['avdataend'])) {
// keep scanning
} else {
$ThisFileInfo['aac']['frames'] = $framenumber;
$ThisFileInfo['playtime_seconds'] = ($ThisFileInfo['avdataend'] / $byteoffset) * (($framenumber * 1024) / $ThisFileInfo['aac']['header']['sample_frequency']); // (1 / % of file scanned) * (samples / (samples/sec)) = seconds
if ($ThisFileInfo['playtime_seconds'] == 0) {
$ThisFileInfo['error'][] = 'Corrupt AAC file: playtime_seconds == zero';
return false;
}
$ThisFileInfo['audio']['bitrate'] = (($ThisFileInfo['avdataend'] - $ThisFileInfo['avdataoffset']) * 8) / $ThisFileInfo['playtime_seconds'];
ksort($ThisFileInfo['aac']['bitrate_distribution']);
$ThisFileInfo['audio']['encoder_options'] = $ThisFileInfo['aac']['header_type'].' '.$ThisFileInfo['aac']['header']['profile_text'];
return true;
}
}
// should never get here.
}
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');
}
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][$profileid] : 'invalid');
}
function AACchannelCountCalculate($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;
}
}
?>