rlm@3: <?php
rlm@3: // +----------------------------------------------------------------------+
rlm@3: // | PHP version 5                                                        |
rlm@3: // +----------------------------------------------------------------------+
rlm@3: // | Copyright (c) 2002-2006 James Heinrich, Allan Hansen                 |
rlm@3: // +----------------------------------------------------------------------+
rlm@3: // | This source file is subject to version 2 of the GPL license,         |
rlm@3: // | that is bundled with this package in the file license.txt and is     |
rlm@3: // | available through the world-wide-web at the following url:           |
rlm@3: // | http://www.gnu.org/copyleft/gpl.html                                 |
rlm@3: // +----------------------------------------------------------------------+
rlm@3: // | getID3() - http://getid3.sourceforge.net or http://www.getid3.org    |
rlm@3: // +----------------------------------------------------------------------+
rlm@3: // | Authors: James Heinrich <infoØgetid3*org>                            |
rlm@3: // |          Allan Hansen <ahØartemis*dk>                                |
rlm@3: // +----------------------------------------------------------------------+
rlm@3: // | module.audio.aac_adts.php                                            |
rlm@3: // | Module for analyzing AAC files with ADTS header.                     |
rlm@3: // | dependencies: NONE                                                   |
rlm@3: // +----------------------------------------------------------------------+
rlm@3: //
rlm@3: // $Id: module.audio.aac_adts.php,v 1.4 2006/11/02 10:48:01 ah Exp $
rlm@3: 
rlm@3:         
rlm@3:         
rlm@3: class getid3_aac_adts extends getid3_handler
rlm@3: {
rlm@3: 
rlm@3:     public $option_max_frames_to_scan   = 1000000;
rlm@3:     public $option_return_extended_info = false;
rlm@3:     
rlm@3: 
rlm@3:     private $decbin_cache;
rlm@3:     private $bitrate_cache;
rlm@3:     
rlm@3: 
rlm@3: 
rlm@3:     public function __construct(getID3 $getid3) {
rlm@3:         
rlm@3:         parent::__construct($getid3);
rlm@3:     
rlm@3:         // Populate bindec_cache
rlm@3:         for ($i = 0; $i < 256; $i++) {
rlm@3:                 $this->decbin_cache[chr($i)] = str_pad(decbin($i), 8, '0', STR_PAD_LEFT);
rlm@3:         }
rlm@3:         
rlm@3:         // Init cache
rlm@3:         $this->bitrate_cache = array ();
rlm@3:         
rlm@3:         // Fast scanning?
rlm@3:         if (!$getid3->option_accurate_results) {
rlm@3:             $this->option_max_frames_to_scan = 200;
rlm@3:             $getid3->warning('option_accurate_results set to false - bitrate and playing time are not accurate.');
rlm@3:         }
rlm@3:     }
rlm@3:     
rlm@3:         
rlm@3: 
rlm@3:     public function Analyze() {
rlm@3:         
rlm@3:         $getid3 = $this->getid3;
rlm@3: 
rlm@3:         // based loosely on code from AACfile by Jurgen Faul  <jfaulØgmx.de>
rlm@3:         // http://jfaul.de/atl  or  http://j-faul.virtualave.net/atl/atl.html
rlm@3: 
rlm@3: 
rlm@3:         // http://faac.sourceforge.net/wiki/index.php?page=ADTS
rlm@3: 
rlm@3:         // * ADTS Fixed Header: these don't change from frame to frame
rlm@3:         // syncword                                       12    always: '111111111111'
rlm@3:         // ID                                              1    0: MPEG-4, 1: MPEG-2
rlm@3:         // layer                                           2    always: '00'
rlm@3:         // protection_absent                               1
rlm@3:         // profile                                         2
rlm@3:         // sampling_frequency_index                        4
rlm@3:         // private_bit                                     1
rlm@3:         // channel_configuration                           3
rlm@3:         // original/copy                                   1
rlm@3:         // home                                            1
rlm@3:         // emphasis                                        2    only if ID == 0 (ie MPEG-4)
rlm@3: 
rlm@3:         // * ADTS Variable Header: these can change from frame to frame
rlm@3:         // copyright_identification_bit                    1
rlm@3:         // copyright_identification_start                  1
rlm@3:         // aac_frame_length                               13    length of the frame including header (in bytes)
rlm@3:         // adts_buffer_fullness                           11    0x7FF indicates VBR
rlm@3:         // no_raw_data_blocks_in_frame                     2
rlm@3: 
rlm@3:         // * ADTS Error check
rlm@3:         // crc_check                                      16    only if protection_absent == 0
rlm@3: 
rlm@3:         $getid3->info['aac']['header'] = array () ;
rlm@3:         $info_aac        = &$getid3->info['aac'];
rlm@3:         $info_aac_header = & $info_aac['header'];
rlm@3: 
rlm@3:         $byte_offset  = $frame_number = 0;
rlm@3: 
rlm@3:         while (true) {
rlm@3:             
rlm@3:             // Breaks out when end-of-file encountered, or invalid data found,
rlm@3:             // or MaxFramesToScan frames have been scanned
rlm@3: 
rlm@3:             fseek($getid3->fp, $byte_offset, SEEK_SET);
rlm@3: 
rlm@3:             // First get substring
rlm@3:             $sub_string = fread($getid3->fp, 10);
rlm@3:             $sub_string_length = strlen($sub_string);
rlm@3:             if ($sub_string_length != 10) {
rlm@3:                 throw new getid3_exception('Failed to read 10 bytes at offset '.(ftell($getid3->fp) - $sub_string_length).' (only read '.$sub_string_length.' bytes)');
rlm@3:             }
rlm@3: 
rlm@3:             // Initialise $aac_header_bitstream
rlm@3:             $aac_header_bitstream = '';
rlm@3: 
rlm@3:             // Loop thru substring chars
rlm@3:             for ($i = 0; $i < 10; $i++) {
rlm@3:                 $aac_header_bitstream .= $this->decbin_cache[$sub_string[$i]];
rlm@3:             }
rlm@3:             
rlm@3:             $sync_test  = bindec(substr($aac_header_bitstream, 0, 12));
rlm@3:             $bit_offset = 12;
rlm@3:             
rlm@3:             if ($sync_test != 0x0FFF) {
rlm@3:                 throw new getid3_exception('Synch pattern (0x0FFF) not found at offset '.(ftell($getid3->fp) - 10).' (found 0x0'.strtoupper(dechex($sync_test)).' instead)');
rlm@3:             }
rlm@3: 
rlm@3:             // Only gather info once - this takes time to do 1000 times!
rlm@3:             if ($frame_number > 0) {
rlm@3: 
rlm@3:                 // MPEG-4: 20,  // MPEG-2: 18
rlm@3:                 $bit_offset += $aac_header_bitstream[$bit_offset] ? 18 : 20;
rlm@3:             } 
rlm@3:         
rlm@3:             // Gather info for first frame only - this takes time to do 1000 times!
rlm@3:             else {
rlm@3: 
rlm@3:                 $info_aac['header_type']             = 'ADTS';
rlm@3:                 $info_aac_header['synch']            = $sync_test;
rlm@3:                 $getid3->info['fileformat']          = 'aac';
rlm@3:                 $getid3->info['audio']['dataformat'] = 'aac';
rlm@3: 
rlm@3:                 $info_aac_header['mpeg_version']     = $aac_header_bitstream{$bit_offset++} == '0' ? 4 : 2;
rlm@3:                 $info_aac_header['layer']            = bindec(substr($aac_header_bitstream, $bit_offset, 2));
rlm@3:                 $bit_offset += 2;
rlm@3:                 
rlm@3:                 if ($info_aac_header['layer'] != 0) {
rlm@3:                     throw new getid3_exception('Layer error - expected 0x00, found 0x'.dechex($info_aac_header['layer']).' instead');
rlm@3:                 }
rlm@3:                 
rlm@3:                 $info_aac_header['crc_present'] = $aac_header_bitstream{$bit_offset++} == '0' ? true : false;
rlm@3:                 
rlm@3:                 $info_aac_header['profile_id'] = bindec(substr($aac_header_bitstream, $bit_offset, 2));
rlm@3:                 $bit_offset += 2;
rlm@3:                 
rlm@3:                 $info_aac_header['profile_text'] = getid3_aac_adts::AACprofileLookup($info_aac_header['profile_id'], $info_aac_header['mpeg_version']);
rlm@3: 
rlm@3:                 $info_aac_header['sample_frequency_index'] = bindec(substr($aac_header_bitstream, $bit_offset, 4));
rlm@3:                 $bit_offset += 4;
rlm@3:                 
rlm@3:                 $info_aac_header['sample_frequency'] = getid3_aac_adts::AACsampleRateLookup($info_aac_header['sample_frequency_index']);
rlm@3:                 
rlm@3:                 $getid3->info['audio']['sample_rate'] = $info_aac_header['sample_frequency'];
rlm@3: 
rlm@3:                 $info_aac_header['private'] = $aac_header_bitstream{$bit_offset++} == 1;
rlm@3:                 
rlm@3:                 $info_aac_header['channel_configuration'] = $getid3->info['audio']['channels'] = bindec(substr($aac_header_bitstream, $bit_offset, 3));
rlm@3:                 $bit_offset += 3;
rlm@3:                 
rlm@3:                 $info_aac_header['original'] = $aac_header_bitstream{$bit_offset++} == 1;
rlm@3:                 $info_aac_header['home']     = $aac_header_bitstream{$bit_offset++} == 1;
rlm@3: 
rlm@3:                 if ($info_aac_header['mpeg_version'] == 4) {
rlm@3:                     $info_aac_header['emphasis']  = bindec(substr($aac_header_bitstream, $bit_offset, 2));
rlm@3:                     $bit_offset += 2;
rlm@3:                 }
rlm@3: 
rlm@3:                 if ($this->option_return_extended_info) {
rlm@3: 
rlm@3:                     $info_aac[$frame_number]['copyright_id_bit']   = $aac_header_bitstream{$bit_offset++} == 1;
rlm@3:                     $info_aac[$frame_number]['copyright_id_start'] = $aac_header_bitstream{$bit_offset++} == 1;
rlm@3: 
rlm@3:                 }  else {
rlm@3:                     $bit_offset += 2;
rlm@3:                 }
rlm@3:             }
rlm@3: 
rlm@3:             $frame_length = bindec(substr($aac_header_bitstream, $bit_offset, 13));
rlm@3: 
rlm@3:             if (!isset($this->bitrate_cache[$frame_length])) {
rlm@3:                 $this->bitrate_cache[$frame_length] = ($info_aac_header['sample_frequency'] / 1024) * $frame_length * 8;
rlm@3:             }
rlm@3:             @$info_aac['bitrate_distribution'][$this->bitrate_cache[$frame_length]]++;
rlm@3: 
rlm@3:             $info_aac[$frame_number]['aac_frame_length']     = $frame_length;
rlm@3:             $bit_offset += 13;
rlm@3:             
rlm@3:             $info_aac[$frame_number]['adts_buffer_fullness'] = bindec(substr($aac_header_bitstream, $bit_offset, 11));
rlm@3:             $bit_offset += 11;
rlm@3:             
rlm@3:             $getid3->info['audio']['bitrate_mode'] = ($info_aac[$frame_number]['adts_buffer_fullness'] == 0x07FF) ? 'vbr' : 'cbr';
rlm@3:             
rlm@3:             $info_aac[$frame_number]['num_raw_data_blocks']  = bindec(substr($aac_header_bitstream, $bit_offset, 2));
rlm@3:             $bit_offset += 2;
rlm@3: 
rlm@3:             if ($info_aac_header['crc_present']) {
rlm@3:                 $bit_offset += 16;
rlm@3:             }
rlm@3: 
rlm@3:             if (!$this->option_return_extended_info) {
rlm@3:                 unset($info_aac[$frame_number]);
rlm@3:             }
rlm@3: 
rlm@3:             $byte_offset += $frame_length;
rlm@3:             if ((++$frame_number < $this->option_max_frames_to_scan) && (($byte_offset + 10) < $getid3->info['avdataend'])) {
rlm@3: 
rlm@3:                 // keep scanning
rlm@3: 
rlm@3:             } else {
rlm@3: 
rlm@3:                 $info_aac['frames']    = $frame_number;
rlm@3:                 $getid3->info['playtime_seconds'] = ($getid3->info['avdataend'] / $byte_offset) * (($frame_number * 1024) / $info_aac_header['sample_frequency']);  // (1 / % of file scanned) * (samples / (samples/sec)) = seconds
rlm@3:                 $getid3->info['audio']['bitrate'] = (($getid3->info['avdataend'] - $getid3->info['avdataoffset']) * 8) / $getid3->info['playtime_seconds'];
rlm@3:                 ksort($info_aac['bitrate_distribution']);
rlm@3: 
rlm@3:                 $getid3->info['audio']['encoder_options'] = $info_aac['header_type'].' '.$info_aac_header['profile_text'];
rlm@3: 
rlm@3:                 return true;
rlm@3:             }
rlm@3:         }
rlm@3:     }
rlm@3: 
rlm@3:     
rlm@3:     
rlm@3:     public static function AACsampleRateLookup($samplerate_id) {
rlm@3:         
rlm@3:         static $lookup = array (
rlm@3:             0  => 96000,
rlm@3:             1  => 88200,
rlm@3:             2  => 64000,
rlm@3:             3  => 48000,
rlm@3:             4  => 44100,
rlm@3:             5  => 32000,
rlm@3:             6  => 24000,
rlm@3:             7  => 22050,
rlm@3:             8  => 16000,
rlm@3:             9  => 12000,
rlm@3:             10 => 11025,
rlm@3:             11 => 8000,
rlm@3:             12 => 0,
rlm@3:             13 => 0,
rlm@3:             14 => 0,
rlm@3:             15 => 0
rlm@3:         );
rlm@3:         return (isset($lookup[$samplerate_id]) ? $lookup[$samplerate_id] : 'invalid');
rlm@3:     }
rlm@3: 
rlm@3: 
rlm@3: 
rlm@3:     public static function AACprofileLookup($profile_id, $mpeg_version) {
rlm@3:         
rlm@3:         static $lookup = array (
rlm@3:             2 => array ( 
rlm@3:                 0 => 'Main profile',
rlm@3:                 1 => 'Low Complexity profile (LC)',
rlm@3:                 2 => 'Scalable Sample Rate profile (SSR)',
rlm@3:                 3 => '(reserved)'
rlm@3:             ),            
rlm@3:             4 => array (
rlm@3:                 0 => 'AAC_MAIN',
rlm@3:                 1 => 'AAC_LC',
rlm@3:                 2 => 'AAC_SSR',
rlm@3:                 3 => 'AAC_LTP'
rlm@3:             )
rlm@3:         );
rlm@3:         return (isset($lookup[$mpeg_version][$profile_id]) ? $lookup[$mpeg_version][$profile_id] : 'invalid');
rlm@3:     }
rlm@3: 
rlm@3: 
rlm@3: }
rlm@3: 
rlm@3: 
rlm@3: ?>