module.audio.aac.php

一个用PHP编写的

<?php
/////////////////////////////////////////////////////////////////
/// getID3() by James Heinrich <[e-mail]>               //
//  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豨mx.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