<?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  <jfaulØgmx.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

            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 {