diff options
Diffstat (limited to 'modules/getid3/module.audio.aac_adts.php')
| -rw-r--r-- | modules/getid3/module.audio.aac_adts.php | 282 |
1 files changed, 282 insertions, 0 deletions
diff --git a/modules/getid3/module.audio.aac_adts.php b/modules/getid3/module.audio.aac_adts.php new file mode 100644 index 00000000..aa7f8f73 --- /dev/null +++ b/modules/getid3/module.audio.aac_adts.php @@ -0,0 +1,282 @@ +<?php +// +----------------------------------------------------------------------+ +// | PHP version 5 | +// +----------------------------------------------------------------------+ +// | Copyright (c) 2002-2006 James Heinrich, Allan Hansen | +// +----------------------------------------------------------------------+ +// | This source file is subject to version 2 of the GPL license, | +// | that is bundled with this package in the file license.txt and is | +// | available through the world-wide-web at the following url: | +// | http://www.gnu.org/copyleft/gpl.html | +// +----------------------------------------------------------------------+ +// | getID3() - http://getid3.sourceforge.net or http://www.getid3.org | +// +----------------------------------------------------------------------+ +// | Authors: James Heinrich <infoØgetid3*org> | +// | Allan Hansen <ahØartemis*dk> | +// +----------------------------------------------------------------------+ +// | module.audio.aac_adts.php | +// | Module for analyzing AAC files with ADTS header. | +// | dependencies: NONE | +// +----------------------------------------------------------------------+ +// +// $Id: module.audio.aac_adts.php,v 1.4 2006/11/02 10:48:01 ah Exp $ + + + +class getid3_aac_adts extends getid3_handler +{ + + public $option_max_frames_to_scan = 1000000; + public $option_return_extended_info = false; + + + private $decbin_cache; + private $bitrate_cache; + + + + public function __construct(getID3 $getid3) { + + parent::__construct($getid3); + + // Populate bindec_cache + for ($i = 0; $i < 256; $i++) { + $this->decbin_cache[chr($i)] = str_pad(decbin($i), 8, '0', STR_PAD_LEFT); + } + + // Init cache + $this->bitrate_cache = array (); + + // Fast scanning? + if (!$getid3->option_accurate_results) { + $this->option_max_frames_to_scan = 200; + $getid3->warning('option_accurate_results set to false - bitrate and playing time are not accurate.'); + } + } + + + + public function Analyze() { + + $getid3 = $this->getid3; + + // 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 + + $getid3->info['aac']['header'] = array () ; + $info_aac = &$getid3->info['aac']; + $info_aac_header = & $info_aac['header']; + + $byte_offset = $frame_number = 0; + + while (true) { + + // Breaks out when end-of-file encountered, or invalid data found, + // or MaxFramesToScan frames have been scanned + + fseek($getid3->fp, $byte_offset, SEEK_SET); + + // First get substring + $sub_string = fread($getid3->fp, 10); + $sub_string_length = strlen($sub_string); + if ($sub_string_length != 10) { + throw new getid3_exception('Failed to read 10 bytes at offset '.(ftell($getid3->fp) - $sub_string_length).' (only read '.$sub_string_length.' bytes)'); + } + + // Initialise $aac_header_bitstream + $aac_header_bitstream = ''; + + // Loop thru substring chars + for ($i = 0; $i < 10; $i++) { + $aac_header_bitstream .= $this->decbin_cache[$sub_string[$i]]; + } + + $sync_test = bindec(substr($aac_header_bitstream, 0, 12)); + $bit_offset = 12; + + if ($sync_test != 0x0FFF) { + throw new getid3_exception('Synch pattern (0x0FFF) not found at offset '.(ftell($getid3->fp) - 10).' (found 0x0'.strtoupper(dechex($sync_test)).' instead)'); + } + + // Only gather info once - this takes time to do 1000 times! + if ($frame_number > 0) { + + // MPEG-4: 20, // MPEG-2: 18 + $bit_offset += $aac_header_bitstream[$bit_offset] ? 18 : 20; + } + + // Gather info for first frame only - this takes time to do 1000 times! + else { + + $info_aac['header_type'] = 'ADTS'; + $info_aac_header['synch'] = $sync_test; + $getid3->info['fileformat'] = 'aac'; + $getid3->info['audio']['dataformat'] = 'aac'; + + $info_aac_header['mpeg_version'] = $aac_header_bitstream{$bit_offset++} == '0' ? 4 : 2; + $info_aac_header['layer'] = bindec(substr($aac_header_bitstream, $bit_offset, 2)); + $bit_offset += 2; + + if ($info_aac_header['layer'] != 0) { + throw new getid3_exception('Layer error - expected 0x00, found 0x'.dechex($info_aac_header['layer']).' instead'); + } + + $info_aac_header['crc_present'] = $aac_header_bitstream{$bit_offset++} == '0' ? true : false; + + $info_aac_header['profile_id'] = bindec(substr($aac_header_bitstream, $bit_offset, 2)); + $bit_offset += 2; + + $info_aac_header['profile_text'] = getid3_aac_adts::AACprofileLookup($info_aac_header['profile_id'], $info_aac_header['mpeg_version']); + + $info_aac_header['sample_frequency_index'] = bindec(substr($aac_header_bitstream, $bit_offset, 4)); + $bit_offset += 4; + + $info_aac_header['sample_frequency'] = getid3_aac_adts::AACsampleRateLookup($info_aac_header['sample_frequency_index']); + + $getid3->info['audio']['sample_rate'] = $info_aac_header['sample_frequency']; + + $info_aac_header['private'] = $aac_header_bitstream{$bit_offset++} == 1; + + $info_aac_header['channel_configuration'] = $getid3->info['audio']['channels'] = bindec(substr($aac_header_bitstream, $bit_offset, 3)); + $bit_offset += 3; + + $info_aac_header['original'] = $aac_header_bitstream{$bit_offset++} == 1; + $info_aac_header['home'] = $aac_header_bitstream{$bit_offset++} == 1; + + if ($info_aac_header['mpeg_version'] == 4) { + $info_aac_header['emphasis'] = bindec(substr($aac_header_bitstream, $bit_offset, 2)); + $bit_offset += 2; + } + + if ($this->option_return_extended_info) { + + $info_aac[$frame_number]['copyright_id_bit'] = $aac_header_bitstream{$bit_offset++} == 1; + $info_aac[$frame_number]['copyright_id_start'] = $aac_header_bitstream{$bit_offset++} == 1; + + } else { + $bit_offset += 2; + } + } + + $frame_length = bindec(substr($aac_header_bitstream, $bit_offset, 13)); + + if (!isset($this->bitrate_cache[$frame_length])) { + $this->bitrate_cache[$frame_length] = ($info_aac_header['sample_frequency'] / 1024) * $frame_length * 8; + } + @$info_aac['bitrate_distribution'][$this->bitrate_cache[$frame_length]]++; + + $info_aac[$frame_number]['aac_frame_length'] = $frame_length; + $bit_offset += 13; + + $info_aac[$frame_number]['adts_buffer_fullness'] = bindec(substr($aac_header_bitstream, $bit_offset, 11)); + $bit_offset += 11; + + $getid3->info['audio']['bitrate_mode'] = ($info_aac[$frame_number]['adts_buffer_fullness'] == 0x07FF) ? 'vbr' : 'cbr'; + + $info_aac[$frame_number]['num_raw_data_blocks'] = bindec(substr($aac_header_bitstream, $bit_offset, 2)); + $bit_offset += 2; + + if ($info_aac_header['crc_present']) { + $bit_offset += 16; + } + + if (!$this->option_return_extended_info) { + unset($info_aac[$frame_number]); + } + + $byte_offset += $frame_length; + if ((++$frame_number < $this->option_max_frames_to_scan) && (($byte_offset + 10) < $getid3->info['avdataend'])) { + + // keep scanning + + } else { + + $info_aac['frames'] = $frame_number; + $getid3->info['playtime_seconds'] = ($getid3->info['avdataend'] / $byte_offset) * (($frame_number * 1024) / $info_aac_header['sample_frequency']); // (1 / % of file scanned) * (samples / (samples/sec)) = seconds + $getid3->info['audio']['bitrate'] = (($getid3->info['avdataend'] - $getid3->info['avdataoffset']) * 8) / $getid3->info['playtime_seconds']; + ksort($info_aac['bitrate_distribution']); + + $getid3->info['audio']['encoder_options'] = $info_aac['header_type'].' '.$info_aac_header['profile_text']; + + return true; + } + } + } + + + + public static function AACsampleRateLookup($samplerate_id) { + + static $lookup = array ( + 0 => 96000, + 1 => 88200, + 2 => 64000, + 3 => 48000, + 4 => 44100, + 5 => 32000, + 6 => 24000, + 7 => 22050, + 8 => 16000, + 9 => 12000, + 10 => 11025, + 11 => 8000, + 12 => 0, + 13 => 0, + 14 => 0, + 15 => 0 + ); + return (isset($lookup[$samplerate_id]) ? $lookup[$samplerate_id] : 'invalid'); + } + + + + public static function AACprofileLookup($profile_id, $mpeg_version) { + + static $lookup = array ( + 2 => array ( + 0 => 'Main profile', + 1 => 'Low Complexity profile (LC)', + 2 => 'Scalable Sample Rate profile (SSR)', + 3 => '(reserved)' + ), + 4 => array ( + 0 => 'AAC_MAIN', + 1 => 'AAC_LC', + 2 => 'AAC_SSR', + 3 => 'AAC_LTP' + ) + ); + return (isset($lookup[$mpeg_version][$profile_id]) ? $lookup[$mpeg_version][$profile_id] : 'invalid'); + } + + +} + + +?>
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