getid3_ac3::AC3dolbySurroundModeLookup() - Code Metrics - mambax7/xoopseditors - Measure and Improve Code Quality continuously with Scrutinizer

getid3_ac3::AC3dolbySurroundModeLookup() A
last analyzed 2022-06-12 05:55 UTC

↳ Parent: getid3_ac3

Complexity

Conditions	2
Paths	2

Size

Total Lines	9
Code Lines	6

Duplication

Lines	0
Ratio	0 %

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
cc	2
eloc	6
c	1
b	0
f	0
nc	2
nop	1
dl	0
loc	9
rs	10

<?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 <info�getid3*org>                            |
// |          Allan Hansen <ah�artemis*dk>                                |
// +----------------------------------------------------------------------+
// | module.audio.ac3.php                                                 |
// | Module for analyzing AC-3 (aka Dolby Digital) audio files            |
// | dependencies: NONE                                                   |
// +----------------------------------------------------------------------+
//
// $Id: module.audio.ac3.php,v 1.3 2006/11/02 10:48:01 ah Exp $

class getid3_ac3 extends getid3_handler
{

    public function Analyze()
    {
        $getid3 = $this->getid3;

        // http://www.atsc.org/standards/a_52a.pdf

        $getid3->info['fileformat']            = 'ac3';
        $getid3->info['audio']['dataformat']   = 'ac3';
        $getid3->info['audio']['bitrate_mode'] = 'cbr';
        $getid3->info['audio']['lossless']     = false;

        $getid3->info['ac3']['raw']['bsi'] = [];
        $info_ac3                          = &$getid3->info['ac3'];
        $info_ac3_raw                      = &$info_ac3['raw'];
        $info_ac3_raw_bsi                  = &$info_ac3_raw['bsi'];

        // An AC-3 serial coded audio bit stream is made up of a sequence of synchronization frames
        // Each synchronization frame contains 6 coded audio blocks (AB), each of which represent 256
        // new audio samples per channel. A synchronization information (SI) header at the beginning
        // of each frame contains information needed to acquire and maintain synchronization. A
        // bit stream information (BSI) header follows SI, and contains parameters describing the coded
        // audio service. The coded audio blocks may be followed by an auxiliary data (Aux) field. At the
        // end of each frame is an error check field that includes a CRC word for error detection. An
        // additional CRC word is located in the SI header, the use of which, by a decoder, is optional.
        //
        // syncinfo() | bsi() | AB0 | AB1 | AB2 | AB3 | AB4 | AB5 | Aux | CRC

        $this->fseek($getid3->info['avdataoffset'], SEEK_SET);
        $ac3_header['syncinfo']                 = $this->fread(5);

        $info_ac3_raw['synchinfo']['synchword'] = substr($ac3_header['syncinfo'], 0, 2);

        if ("\x0B\x77" != $info_ac3_raw['synchinfo']['synchword']) {
            throw new getid3_exception('Expecting "\x0B\x77" at offset ' . $getid3->info['avdataoffset'] . ', found \x' . strtoupper(dechex($ac3_header['syncinfo']{0})) . '\x' . strtoupper(dechex($ac3_header['syncinfo']{1})) . ' instead');
        }

        // syncinfo() {
        //      syncword    16
        //      crc1        16
        //      fscod        2
        //      frmsizecod   6
        // } /* end of syncinfo */

        $info_ac3_raw['synchinfo']['crc1']       = getid3_lib::LittleEndian2Int(substr($ac3_header['syncinfo'], 2, 2));
        $ac3_synchinfo_fscod_frmsizecod          = getid3_lib::LittleEndian2Int(substr($ac3_header['syncinfo'], 4, 1));
        $info_ac3_raw['synchinfo']['fscod']      = ($ac3_synchinfo_fscod_frmsizecod & 0xC0) >> 6;
        $info_ac3_raw['synchinfo']['frmsizecod'] = ($ac3_synchinfo_fscod_frmsizecod & 0x3F);

        $info_ac3['sample_rate'] = getid3_ac3::AC3sampleRateCodeLookup($info_ac3_raw['synchinfo']['fscod']);
        if ($info_ac3_raw['synchinfo']['fscod'] <= 3) {
            $getid3->info['audio']['sample_rate'] = $info_ac3['sample_rate'];
        }

        $info_ac3['frame_length']         = getid3_ac3::AC3frameSizeLookup($info_ac3_raw['synchinfo']['frmsizecod'], $info_ac3_raw['synchinfo']['fscod']);
        $info_ac3['bitrate']              = getid3_ac3::AC3bitrateLookup($info_ac3_raw['synchinfo']['frmsizecod']);
        $getid3->info['audio']['bitrate'] = $info_ac3['bitrate'];

        $ac3_header['bsi'] = getid3_lib::BigEndian2Bin($this->fread(15));

        $info_ac3_raw_bsi['bsid'] = bindec(substr($ac3_header['bsi'], 0, 5));
        if ($info_ac3_raw_bsi['bsid'] > 8) {
            // Decoders which can decode version 8 will thus be able to decode version numbers less than 8.
            // If this standard is extended by the addition of additional elements or features, a value of bsid greater than 8 will be used.
            // Decoders built to this version of the standard will not be able to decode versions with bsid greater than 8.
            throw new getid3_exception('Bit stream identification is version ' . $info_ac3_raw_bsi['bsid'] . ', but getID3() only understands up to version 8');
        }

        $info_ac3_raw_bsi['bsmod'] = bindec(substr($ac3_header['bsi'], 5, 3));
        $info_ac3_raw_bsi['acmod'] = bindec(substr($ac3_header['bsi'], 8, 3));

        $info_ac3['service_type'] = getid3_ac3::AC3serviceTypeLookup($info_ac3_raw_bsi['bsmod'], $info_ac3_raw_bsi['acmod']);
        $ac3_coding_mode          = getid3_ac3::AC3audioCodingModeLookup($info_ac3_raw_bsi['acmod']);
        foreach ($ac3_coding_mode as $key => $value) {
            $info_ac3[$key] = $value;
        }
        switch ($info_ac3_raw_bsi['acmod']) {
            case 0:
            case 1:
                $getid3->info['audio']['channelmode'] = 'mono';
                break;
            case 3:
            case 4:
                $getid3->info['audio']['channelmode'] = 'stereo';
                break;
            default:
                $getid3->info['audio']['channelmode'] = 'surround';
                break;
        }
        $getid3->info['audio']['channels'] = $info_ac3['num_channels'];

        $offset = 11;

        if ($info_ac3_raw_bsi['acmod'] & 0x01) {
            // If the lsb of acmod is a 1, center channel is in use and cmixlev follows in the bit stream.
            $info_ac3_raw_bsi['cmixlev']  = bindec(substr($ac3_header['bsi'], $offset, 2));
            $info_ac3['center_mix_level'] = getid3_ac3::AC3centerMixLevelLookup($info_ac3_raw_bsi['cmixlev']);
            $offset                       += 2;
        }

        if ($info_ac3_raw_bsi['acmod'] & 0x04) {
            // If the msb of acmod is a 1, surround channels are in use and surmixlev follows in the bit stream.
            $info_ac3_raw_bsi['surmixlev']  = bindec(substr($ac3_header['bsi'], $offset, 2));
            $info_ac3['surround_mix_level'] = getid3_ac3::AC3surroundMixLevelLookup($info_ac3_raw_bsi['surmixlev']);
            $offset                         += 2;
        }

        if (0x02 == $info_ac3_raw_bsi['acmod']) {
            // When operating in the two channel mode, this 2-bit code indicates whether or not the program has been encoded in Dolby Surround.
            $info_ac3_raw_bsi['dsurmod']     = bindec(substr($ac3_header['bsi'], $offset, 2));
            $info_ac3['dolby_surround_mode'] = getid3_ac3::AC3dolbySurroundModeLookup($info_ac3_raw_bsi['dsurmod']);
            $offset                          += 2;
        }

        $info_ac3_raw_bsi['lfeon'] = '1' == $ac3_header['bsi']{$offset++};
        $info_ac3['lfe_enabled']   = $info_ac3_raw_bsi['lfeon'];
        if ($info_ac3_raw_bsi['lfeon']) {
            $getid3->info['audio']['channels'] .= '.1';
        }

        $info_ac3['channels_enabled'] = getid3_ac3::AC3channelsEnabledLookup($info_ac3_raw_bsi['acmod'], $info_ac3_raw_bsi['lfeon']);

        // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1�31.
        // The value of 0 is reserved. The values of 1 to 31 are interpreted as -1 dB to -31 dB with respect to digital 100 percent.
        $info_ac3_raw_bsi['dialnorm']       = bindec(substr($ac3_header['bsi'], $offset, 5));
        $offset                             += 5;
        $info_ac3['dialogue_normalization'] = '-' . $info_ac3_raw_bsi['dialnorm'] . 'dB';

        $info_ac3_raw_bsi['compre_flag'] = '1' == $ac3_header['bsi']{$offset++};
        if ($info_ac3_raw_bsi['compre_flag']) {
            $info_ac3_raw_bsi['compr'] = bindec(substr($ac3_header['bsi'], $offset, 8));
            $offset                    += 8;

            $info_ac3['heavy_compression'] = getid3_ac3::AC3heavyCompression($info_ac3_raw_bsi['compr']);
        }

        $info_ac3_raw_bsi['langcode_flag'] = '1' == $ac3_header['bsi']{$offset++};
        if ($info_ac3_raw_bsi['langcode_flag']) {
            $info_ac3_raw_bsi['langcod'] = bindec(substr($ac3_header['bsi'], $offset, 8));
            $offset                      += 8;
        }

        $info_ac3_raw_bsi['audprodie'] = '1' == $ac3_header['bsi']{$offset++};
        if ($info_ac3_raw_bsi['audprodie']) {
            $info_ac3_raw_bsi['mixlevel'] = bindec(substr($ac3_header['bsi'], $offset, 5));
            $offset                       += 5;

            $info_ac3_raw_bsi['roomtyp'] = bindec(substr($ac3_header['bsi'], $offset, 2));
            $offset                      += 2;

            $info_ac3['mixing_level'] = (80 + $info_ac3_raw_bsi['mixlevel']) . 'dB';
            $info_ac3['room_type']    = getid3_ac3::AC3roomTypeLookup($info_ac3_raw_bsi['roomtyp']);
        }

        if (0x00 == $info_ac3_raw_bsi['acmod']) {
            // If acmod is 0, then two completely independent program channels (dual mono)
            // are encoded into the bit stream, and are referenced as Ch1, Ch2. In this case,
            // a number of additional items are present in BSI or audblk to fully describe Ch2.

            // This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1�31.
            // The value of 0 is reserved. The values of 1 to 31 are interpreted as -1 dB to -31 dB with respect to digital 100 percent.
            $info_ac3_raw_bsi['dialnorm2'] = bindec(substr($ac3_header['bsi'], $offset, 5));
            $offset                        += 5;

            $info_ac3['dialogue_normalization2'] = '-' . $info_ac3_raw_bsi['dialnorm2'] . 'dB';

            $info_ac3_raw_bsi['compre_flag2'] = '1' == $ac3_header['bsi']{$offset++};
            if ($info_ac3_raw_bsi['compre_flag2']) {
                $info_ac3_raw_bsi['compr2'] = bindec(substr($ac3_header['bsi'], $offset, 8));
                $offset                     += 8;

                $info_ac3['heavy_compression2'] = getid3_ac3::AC3heavyCompression($info_ac3_raw_bsi['compr2']);
            }

            $info_ac3_raw_bsi['langcode_flag2'] = '1' == $ac3_header['bsi']{$offset++};
            if ($info_ac3_raw_bsi['langcode_flag2']) {
                $info_ac3_raw_bsi['langcod2'] = bindec(substr($ac3_header['bsi'], $offset, 8));
                $offset                       += 8;
            }

            $info_ac3_raw_bsi['audprodie2'] = '1' == $ac3_header['bsi']{$offset++};
            if ($info_ac3_raw_bsi['audprodie2']) {
                $info_ac3_raw_bsi['mixlevel2'] = bindec(substr($ac3_header['bsi'], $offset, 5));
                $offset                        += 5;

                $info_ac3_raw_bsi['roomtyp2'] = bindec(substr($ac3_header['bsi'], $offset, 2));
                $offset                       += 2;

                $info_ac3['mixing_level2'] = (80 + $info_ac3_raw_bsi['mixlevel2']) . 'dB';
                $info_ac3['room_type2']    = getid3_ac3::AC3roomTypeLookup($info_ac3_raw_bsi['roomtyp2']);
            }
        }

        $info_ac3_raw_bsi['copyright'] = '1' == $ac3_header['bsi']{$offset++};

        $info_ac3_raw_bsi['original'] = '1' == $ac3_header['bsi']{$offset++};

        $info_ac3_raw_bsi['timecode1_flag'] = '1' == $ac3_header['bsi']{$offset++};
        if ($info_ac3_raw_bsi['timecode1_flag']) {
            $info_ac3_raw_bsi['timecode1'] = bindec(substr($ac3_header['bsi'], $offset, 14));
            $offset                        += 14;
        }

        $info_ac3_raw_bsi['timecode2_flag'] = '1' == $ac3_header['bsi']{$offset++};
        if ($info_ac3_raw_bsi['timecode2_flag']) {
            $info_ac3_raw_bsi['timecode2'] = bindec(substr($ac3_header['bsi'], $offset, 14));
            $offset                        += 14;
        }

        $info_ac3_raw_bsi['addbsi_flag'] = '1' == $ac3_header['bsi']{$offset++};
        if ($info_ac3_raw_bsi['addbsi_flag']) {
            $info_ac3_raw_bsi['addbsi_length'] = bindec(substr($ac3_header['bsi'], $offset, 6));
            $offset                            += 6;

            $ac3_header['bsi'] .= getid3_lib::BigEndian2Bin($this->fread($info_ac3_raw_bsi['addbsi_length']));

            $info_ac3_raw_bsi['addbsi_data'] = substr($ac3_header['bsi'], 119, $info_ac3_raw_bsi['addbsi_length'] * 8);
        }

        return true;
    }

    public static function AC3sampleRateCodeLookup($fscod)
    {
        static $lookup = [
            0 => 48000,
            1 => 44100,
            2 => 32000,
            3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute.
        ];
        return (isset($lookup[$fscod]) ? $lookup[$fscod] : false);
    }

    public static function AC3serviceTypeLookup($bsmod, $acmod)
    {
        static $lookup = [
            0 => 'main audio service: complete main (CM)',
            1 => 'main audio service: music and effects (ME)',
            2 => 'associated service: visually impaired (VI)',
            3 => 'associated service: hearing impaired (HI)',
            4 => 'associated service: dialogue (D)',
            5 => 'associated service: commentary (C)',
            6 => 'associated service: emergency (E)',
            7 => 'main audio service: karaoke'
        ];

        if (7 == $bsmod && 1 == $acmod) {
            return 'associated service: voice over (VO)';
        }

        return (isset($lookup[$bsmod]) ? $lookup[$bsmod] : false);
    }

    public static function AC3audioCodingModeLookup($acmod)
    {
        // array (channel configuration, # channels (not incl LFE), channel order)
        static $lookup = [
            0 => ['channel_config' => '1+1', 'num_channels' => 2, 'channel_order' => 'Ch1,Ch2'],
            1 => ['channel_config' => '1/0', 'num_channels' => 1, 'channel_order' => 'C'],
            2 => ['channel_config' => '2/0', 'num_channels' => 2, 'channel_order' => 'L,R'],
            3 => ['channel_config' => '3/0', 'num_channels' => 3, 'channel_order' => 'L,C,R'],
            4 => ['channel_config' => '2/1', 'num_channels' => 3, 'channel_order' => 'L,R,S'],
            5 => ['channel_config' => '3/1', 'num_channels' => 4, 'channel_order' => 'L,C,R,S'],
            6 => ['channel_config' => '2/2', 'num_channels' => 4, 'channel_order' => 'L,R,SL,SR'],
            7 => ['channel_config' => '3/2', 'num_channels' => 5, 'channel_order' => 'L,C,R,SL,SR']
        ];
        return (isset($lookup[$acmod]) ? $lookup[$acmod] : false);
    }

    public static function AC3centerMixLevelLookup($cmixlev)
    {
        static $lookup;
        if (!@$lookup) {
            $lookup = [
                0 => pow(2, -3.0 / 6), // 0.707 (�3.0 dB)
                1 => pow(2, -4.5 / 6), // 0.595 (�4.5 dB)
                2 => pow(2, -6.0 / 6), // 0.500 (�6.0 dB)
                3 => 'reserved'
            ];
        }
        return (isset($lookup[$cmixlev]) ? $lookup[$cmixlev] : false);
    }

    public static function AC3surroundMixLevelLookup($surmixlev)
    {
        static $lookup;
        if (!@$lookup) {
            $lookup = [
                0 => pow(2, -3.0 / 6),
                1 => pow(2, -6.0 / 6),
                2 => 0,
                3 => 'reserved'
            ];
        }
        return (isset($lookup[$surmixlev]) ? $lookup[$surmixlev] : false);
    }

    public static function AC3dolbySurroundModeLookup($dsurmod)
    {
        static $lookup = [
            0 => 'not indicated',
            1 => 'Not Dolby Surround encoded',
            2 => 'Dolby Surround encoded',
            3 => 'reserved'
        ];
        return (isset($lookup[$dsurmod]) ? $lookup[$dsurmod] : false);
    }

    public static function AC3channelsEnabledLookup($acmod, $lfeon)
    {
        return [
            'ch1'            => 0 == $acmod,
            'ch2'            => 0 == $acmod,
            'left'           => $acmod > 1,
            'right'          => $acmod > 1,
            'center'         => (bool)($acmod & 0x01),
            'surround_mono'  => 4 == $acmod || 5 == $acmod,
            'surround_left'  => 6 == $acmod || 7 == $acmod,
            'surround_right' => 6 == $acmod || 7 == $acmod,
            'lfe'            => $lfeon
        ];
    }

    public static function AC3heavyCompression($compre)
    {
        // The first four bits indicate gain changes in 6.02dB increments which can be
        // implemented with an arithmetic shift operation. The following four bits
        // indicate linear gain changes, and require a 5-bit multiply.
        // We will represent the two 4-bit fields of compr as follows:
        //   X0 X1 X2 X3 . Y4 Y5 Y6 Y7
        // The meaning of the X values is most simply described by considering X to represent a 4-bit
        // signed integer with values from �8 to +7. The gain indicated by X is then (X + 1) * 6.02 dB. The
        // following table shows this in detail.

        // Meaning of 4 msb of compr
        //  7    +48.16 dB
        //  6    +42.14 dB
        //  5    +36.12 dB
        //  4    +30.10 dB
        //  3    +24.08 dB
        //  2    +18.06 dB
        //  1    +12.04 dB
        //  0     +6.02 dB
        // -1         0 dB
        // -2     �6.02 dB
        // -3    �12.04 dB
        // -4    �18.06 dB
        // -5    �24.08 dB
        // -6    �30.10 dB
        // -7    �36.12 dB
        // -8    �42.14 dB

        $fourbit = str_pad(decbin(($compre & 0xF0) >> 4), 4, '0', STR_PAD_LEFT);
        if ('1' == $fourbit{0}) {
            $log_gain = -8 + bindec(substr($fourbit, 1));
        } else {
            $log_gain = bindec(substr($fourbit, 1));
        }
        $log_gain = ($log_gain + 1) * (20 * log10(2));

        // The value of Y is a linear representation of a gain change of up to �6 dB. Y is considered to
        // be an unsigned fractional integer, with a leading value of 1, or: 0.1 Y4 Y5 Y6 Y7 (base 2). Y can
        // represent values between 0.111112 (or 31/32) and 0.100002 (or 1/2). Thus, Y can represent gain
        // changes from �0.28 dB to �6.02 dB.

        $lin_gain = (16 + ($compre & 0x0F)) / 32;

        // The combination of X and Y values allows compr to indicate gain changes from
        //  48.16 � 0.28 = +47.89 dB, to
        // �42.14 � 6.02 = �48.16 dB.

        return $log_gain - $lin_gain;
    }

    public static function AC3roomTypeLookup($roomtyp)
    {
        static $lookup = [
            0 => 'not indicated',
            1 => 'large room, X curve monitor',
            2 => 'small room, flat monitor',
            3 => 'reserved'
        ];
        return (isset($lookup[$roomtyp]) ? $lookup[$roomtyp] : false);
    }

    public static function AC3frameSizeLookup($frmsizecod, $fscod)
    {
        $padding       = (bool)($frmsizecod % 2);
        $frame_size_id = floor($frmsizecod / 2);

        static $lookup = [
            0  => [128, 138, 192],
            1  => [40, 160, 174, 240],
            2  => [48, 192, 208, 288],
            3  => [56, 224, 242, 336],
            4  => [64, 256, 278, 384],
            5  => [80, 320, 348, 480],
            6  => [96, 384, 416, 576],
            7  => [112, 448, 486, 672],
            8  => [128, 512, 556, 768],
            9  => [160, 640, 696, 960],
            10 => [192, 768, 834, 1152],
            11 => [224, 896, 974, 1344],
            12 => [256, 1024, 1114, 1536],
            13 => [320, 1280, 1392, 1920],
            14 => [384, 1536, 1670, 2304],
            15 => [448, 1792, 1950, 2688],
            16 => [512, 2048, 2228, 3072],
            17 => [576, 2304, 2506, 3456],
            18 => [640, 2560, 2786, 3840]
        ];
        if ((1 == $fscod) && $padding) {
            // frame lengths are padded by 1 word (16 bits) at 44100
            $lookup[$frmsizecod] += 2;
        }
        return (isset($lookup[$frame_size_id][$fscod]) ? $lookup[$frame_size_id][$fscod] : false);
    }

    public static function AC3bitrateLookup($frmsizecod)
    {
        static $lookup = [
            0  => 32000,
            1  => 40000,
            2  => 48000,
            3  => 56000,
            4  => 64000,
            5  => 80000,
            6  => 96000,
            7  => 112000,
            8  => 128000,
            9  => 160000,
            10 => 192000,
            11 => 224000,
            12 => 256000,
            13 => 320000,
            14 => 384000,
            15 => 448000,
            16 => 512000,
            17 => 576000,
            18 => 640000
        ];
        $frame_size_id = floor($frmsizecod / 2);
        return (isset($lookup[$frame_size_id]) ? $lookup[$frame_size_id] : false);
    }

}




1			<?php
2			// +----------------------------------------------------------------------+
3			// \| PHP version 5 \|
4			// +----------------------------------------------------------------------+
5			// \| Copyright (c) 2002-2006 James Heinrich, Allan Hansen \|
6			// +----------------------------------------------------------------------+
7			// \| This source file is subject to version 2 of the GPL license, \|
8			// \| that is bundled with this package in the file license.txt and is \|
9			// \| available through the world-wide-web at the following url: \|
10			// \| http://www.gnu.org/copyleft/gpl.html \|
11			// +----------------------------------------------------------------------+
12			// \| getID3() - http://getid3.sourceforge.net or http://www.getid3.org \|
13			// +----------------------------------------------------------------------+
14			// \| Authors: James Heinrich <info�getid3*org> \|
15			// \| Allan Hansen <ah�artemis*dk> \|
16			// +----------------------------------------------------------------------+
17			// \| module.audio.ac3.php \|
18			// \| Module for analyzing AC-3 (aka Dolby Digital) audio files \|
19			// \| dependencies: NONE \|
20			// +----------------------------------------------------------------------+
21			//
22			// $Id: module.audio.ac3.php,v 1.3 2006/11/02 10:48:01 ah Exp $
23
24			class getid3_ac3 extends getid3_handler
25			{
26
27			public function Analyze()
28			{
29			$getid3 = $this->getid3;
30
31			// http://www.atsc.org/standards/a_52a.pdf
32
33			$getid3->info['fileformat'] = 'ac3';
34			$getid3->info['audio']['dataformat'] = 'ac3';
35			$getid3->info['audio']['bitrate_mode'] = 'cbr';
36			$getid3->info['audio']['lossless'] = false;
37
38			$getid3->info['ac3']['raw']['bsi'] = [];
39			$info_ac3 = &$getid3->info['ac3'];
40			$info_ac3_raw = &$info_ac3['raw'];
41			$info_ac3_raw_bsi = &$info_ac3_raw['bsi'];
42
43			// An AC-3 serial coded audio bit stream is made up of a sequence of synchronization frames
44			// Each synchronization frame contains 6 coded audio blocks (AB), each of which represent 256
45			// new audio samples per channel. A synchronization information (SI) header at the beginning
46			// of each frame contains information needed to acquire and maintain synchronization. A
47			// bit stream information (BSI) header follows SI, and contains parameters describing the coded
48			// audio service. The coded audio blocks may be followed by an auxiliary data (Aux) field. At the
49			// end of each frame is an error check field that includes a CRC word for error detection. An
50			// additional CRC word is located in the SI header, the use of which, by a decoder, is optional.
51			//
52			// syncinfo() \| bsi() \| AB0 \| AB1 \| AB2 \| AB3 \| AB4 \| AB5 \| Aux \| CRC
53
54			$this->fseek($getid3->info['avdataoffset'], SEEK_SET);
55			$ac3_header['syncinfo'] = $this->fread(5);
			0 ignored issues – show Comprehensibility Best Practice introduced 2020-01-01 02:01 UTC by Report Bug Copy Issue Report `$ac3_header` was never initialized. Although not strictly required by PHP, it is generally a good practice to add `$ac3_header = array();` before regardless. Loading history...
56			$info_ac3_raw['synchinfo']['synchword'] = substr($ac3_header['syncinfo'], 0, 2);
57
58			if ("\x0B\x77" != $info_ac3_raw['synchinfo']['synchword']) {
59			throw new getid3_exception('Expecting "\x0B\x77" at offset ' . $getid3->info['avdataoffset'] . ', found \x' . strtoupper(dechex($ac3_header['syncinfo']{0})) . '\x' . strtoupper(dechex($ac3_header['syncinfo']{1})) . ' instead');
60			}
61
62			// syncinfo() {
63			// syncword 16
64			// crc1 16
65			// fscod 2
66			// frmsizecod 6
67			// } /* end of syncinfo */
68
69			$info_ac3_raw['synchinfo']['crc1'] = getid3_lib::LittleEndian2Int(substr($ac3_header['syncinfo'], 2, 2));
70			$ac3_synchinfo_fscod_frmsizecod = getid3_lib::LittleEndian2Int(substr($ac3_header['syncinfo'], 4, 1));
71			$info_ac3_raw['synchinfo']['fscod'] = ($ac3_synchinfo_fscod_frmsizecod & 0xC0) >> 6;
72			$info_ac3_raw['synchinfo']['frmsizecod'] = ($ac3_synchinfo_fscod_frmsizecod & 0x3F);
73
74			$info_ac3['sample_rate'] = getid3_ac3::AC3sampleRateCodeLookup($info_ac3_raw['synchinfo']['fscod']);
75			if ($info_ac3_raw['synchinfo']['fscod'] <= 3) {
76			$getid3->info['audio']['sample_rate'] = $info_ac3['sample_rate'];
77			}
78
79			$info_ac3['frame_length'] = getid3_ac3::AC3frameSizeLookup($info_ac3_raw['synchinfo']['frmsizecod'], $info_ac3_raw['synchinfo']['fscod']);
80			$info_ac3['bitrate'] = getid3_ac3::AC3bitrateLookup($info_ac3_raw['synchinfo']['frmsizecod']);
81			$getid3->info['audio']['bitrate'] = $info_ac3['bitrate'];
82
83			$ac3_header['bsi'] = getid3_lib::BigEndian2Bin($this->fread(15));
84
85			$info_ac3_raw_bsi['bsid'] = bindec(substr($ac3_header['bsi'], 0, 5));
86			if ($info_ac3_raw_bsi['bsid'] > 8) {
87			// Decoders which can decode version 8 will thus be able to decode version numbers less than 8.
88			// If this standard is extended by the addition of additional elements or features, a value of bsid greater than 8 will be used.
89			// Decoders built to this version of the standard will not be able to decode versions with bsid greater than 8.
90			throw new getid3_exception('Bit stream identification is version ' . $info_ac3_raw_bsi['bsid'] . ', but getID3() only understands up to version 8');
91			}
92
93			$info_ac3_raw_bsi['bsmod'] = bindec(substr($ac3_header['bsi'], 5, 3));
94			$info_ac3_raw_bsi['acmod'] = bindec(substr($ac3_header['bsi'], 8, 3));
95
96			$info_ac3['service_type'] = getid3_ac3::AC3serviceTypeLookup($info_ac3_raw_bsi['bsmod'], $info_ac3_raw_bsi['acmod']);
97			$ac3_coding_mode = getid3_ac3::AC3audioCodingModeLookup($info_ac3_raw_bsi['acmod']);
98			foreach ($ac3_coding_mode as $key => $value) {
99			$info_ac3[$key] = $value;
100			}
101			switch ($info_ac3_raw_bsi['acmod']) {
102			case 0:
103			case 1:
104			$getid3->info['audio']['channelmode'] = 'mono';
105			break;
106			case 3:
107			case 4:
108			$getid3->info['audio']['channelmode'] = 'stereo';
109			break;
110			default:
111			$getid3->info['audio']['channelmode'] = 'surround';
112			break;
113			}
114			$getid3->info['audio']['channels'] = $info_ac3['num_channels'];
115
116			$offset = 11;
117
118			if ($info_ac3_raw_bsi['acmod'] & 0x01) {
119			// If the lsb of acmod is a 1, center channel is in use and cmixlev follows in the bit stream.
120			$info_ac3_raw_bsi['cmixlev'] = bindec(substr($ac3_header['bsi'], $offset, 2));
121			$info_ac3['center_mix_level'] = getid3_ac3::AC3centerMixLevelLookup($info_ac3_raw_bsi['cmixlev']);
122			$offset += 2;
123			}
124
125			if ($info_ac3_raw_bsi['acmod'] & 0x04) {
126			// If the msb of acmod is a 1, surround channels are in use and surmixlev follows in the bit stream.
127			$info_ac3_raw_bsi['surmixlev'] = bindec(substr($ac3_header['bsi'], $offset, 2));
128			$info_ac3['surround_mix_level'] = getid3_ac3::AC3surroundMixLevelLookup($info_ac3_raw_bsi['surmixlev']);
129			$offset += 2;
130			}
131
132			if (0x02 == $info_ac3_raw_bsi['acmod']) {
133			// When operating in the two channel mode, this 2-bit code indicates whether or not the program has been encoded in Dolby Surround.
134			$info_ac3_raw_bsi['dsurmod'] = bindec(substr($ac3_header['bsi'], $offset, 2));
135			$info_ac3['dolby_surround_mode'] = getid3_ac3::AC3dolbySurroundModeLookup($info_ac3_raw_bsi['dsurmod']);
136			$offset += 2;
137			}
138
139			$info_ac3_raw_bsi['lfeon'] = '1' == $ac3_header['bsi']{$offset++};
140			$info_ac3['lfe_enabled'] = $info_ac3_raw_bsi['lfeon'];
141			if ($info_ac3_raw_bsi['lfeon']) {
142			$getid3->info['audio']['channels'] .= '.1';
143			}
144
145			$info_ac3['channels_enabled'] = getid3_ac3::AC3channelsEnabledLookup($info_ac3_raw_bsi['acmod'], $info_ac3_raw_bsi['lfeon']);
146
147			// This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1�31.
148			// The value of 0 is reserved. The values of 1 to 31 are interpreted as -1 dB to -31 dB with respect to digital 100 percent.
149			$info_ac3_raw_bsi['dialnorm'] = bindec(substr($ac3_header['bsi'], $offset, 5));
150			$offset += 5;
151			$info_ac3['dialogue_normalization'] = '-' . $info_ac3_raw_bsi['dialnorm'] . 'dB';
152
153			$info_ac3_raw_bsi['compre_flag'] = '1' == $ac3_header['bsi']{$offset++};
154			if ($info_ac3_raw_bsi['compre_flag']) {
155			$info_ac3_raw_bsi['compr'] = bindec(substr($ac3_header['bsi'], $offset, 8));
156			$offset += 8;
157
158			$info_ac3['heavy_compression'] = getid3_ac3::AC3heavyCompression($info_ac3_raw_bsi['compr']);
159			}
160
161			$info_ac3_raw_bsi['langcode_flag'] = '1' == $ac3_header['bsi']{$offset++};
162			if ($info_ac3_raw_bsi['langcode_flag']) {
163			$info_ac3_raw_bsi['langcod'] = bindec(substr($ac3_header['bsi'], $offset, 8));
164			$offset += 8;
165			}
166
167			$info_ac3_raw_bsi['audprodie'] = '1' == $ac3_header['bsi']{$offset++};
168			if ($info_ac3_raw_bsi['audprodie']) {
169			$info_ac3_raw_bsi['mixlevel'] = bindec(substr($ac3_header['bsi'], $offset, 5));
170			$offset += 5;
171
172			$info_ac3_raw_bsi['roomtyp'] = bindec(substr($ac3_header['bsi'], $offset, 2));
173			$offset += 2;
174
175			$info_ac3['mixing_level'] = (80 + $info_ac3_raw_bsi['mixlevel']) . 'dB';
176			$info_ac3['room_type'] = getid3_ac3::AC3roomTypeLookup($info_ac3_raw_bsi['roomtyp']);
177			}
178
179			if (0x00 == $info_ac3_raw_bsi['acmod']) {
180			// If acmod is 0, then two completely independent program channels (dual mono)
181			// are encoded into the bit stream, and are referenced as Ch1, Ch2. In this case,
182			// a number of additional items are present in BSI or audblk to fully describe Ch2.
183
184			// This indicates how far the average dialogue level is below digital 100 percent. Valid values are 1�31.
185			// The value of 0 is reserved. The values of 1 to 31 are interpreted as -1 dB to -31 dB with respect to digital 100 percent.
186			$info_ac3_raw_bsi['dialnorm2'] = bindec(substr($ac3_header['bsi'], $offset, 5));
187			$offset += 5;
188
189			$info_ac3['dialogue_normalization2'] = '-' . $info_ac3_raw_bsi['dialnorm2'] . 'dB';
190
191			$info_ac3_raw_bsi['compre_flag2'] = '1' == $ac3_header['bsi']{$offset++};
192			if ($info_ac3_raw_bsi['compre_flag2']) {
193			$info_ac3_raw_bsi['compr2'] = bindec(substr($ac3_header['bsi'], $offset, 8));
194			$offset += 8;
195
196			$info_ac3['heavy_compression2'] = getid3_ac3::AC3heavyCompression($info_ac3_raw_bsi['compr2']);
197			}
198
199			$info_ac3_raw_bsi['langcode_flag2'] = '1' == $ac3_header['bsi']{$offset++};
200			if ($info_ac3_raw_bsi['langcode_flag2']) {
201			$info_ac3_raw_bsi['langcod2'] = bindec(substr($ac3_header['bsi'], $offset, 8));
202			$offset += 8;
203			}
204
205			$info_ac3_raw_bsi['audprodie2'] = '1' == $ac3_header['bsi']{$offset++};
206			if ($info_ac3_raw_bsi['audprodie2']) {
207			$info_ac3_raw_bsi['mixlevel2'] = bindec(substr($ac3_header['bsi'], $offset, 5));
208			$offset += 5;
209
210			$info_ac3_raw_bsi['roomtyp2'] = bindec(substr($ac3_header['bsi'], $offset, 2));
211			$offset += 2;
212
213			$info_ac3['mixing_level2'] = (80 + $info_ac3_raw_bsi['mixlevel2']) . 'dB';
214			$info_ac3['room_type2'] = getid3_ac3::AC3roomTypeLookup($info_ac3_raw_bsi['roomtyp2']);
215			}
216			}
217
218			$info_ac3_raw_bsi['copyright'] = '1' == $ac3_header['bsi']{$offset++};
219
220			$info_ac3_raw_bsi['original'] = '1' == $ac3_header['bsi']{$offset++};
221
222			$info_ac3_raw_bsi['timecode1_flag'] = '1' == $ac3_header['bsi']{$offset++};
223			if ($info_ac3_raw_bsi['timecode1_flag']) {
224			$info_ac3_raw_bsi['timecode1'] = bindec(substr($ac3_header['bsi'], $offset, 14));
225			$offset += 14;
226			}
227
228			$info_ac3_raw_bsi['timecode2_flag'] = '1' == $ac3_header['bsi']{$offset++};
229			if ($info_ac3_raw_bsi['timecode2_flag']) {
230			$info_ac3_raw_bsi['timecode2'] = bindec(substr($ac3_header['bsi'], $offset, 14));
231			$offset += 14;
232			}
233
234			$info_ac3_raw_bsi['addbsi_flag'] = '1' == $ac3_header['bsi']{$offset++};
235			if ($info_ac3_raw_bsi['addbsi_flag']) {
236			$info_ac3_raw_bsi['addbsi_length'] = bindec(substr($ac3_header['bsi'], $offset, 6));
237			$offset += 6;
238
239			$ac3_header['bsi'] .= getid3_lib::BigEndian2Bin($this->fread($info_ac3_raw_bsi['addbsi_length']));
240
241			$info_ac3_raw_bsi['addbsi_data'] = substr($ac3_header['bsi'], 119, $info_ac3_raw_bsi['addbsi_length'] * 8);
242			}
243
244			return true;
245			}
246
247			public static function AC3sampleRateCodeLookup($fscod)
248			{
249			static $lookup = [
250			0 => 48000,
251			1 => 44100,
252			2 => 32000,
253			3 => 'reserved' // If the reserved code is indicated, the decoder should not attempt to decode audio and should mute.
254			];
255			return (isset($lookup[$fscod]) ? $lookup[$fscod] : false);
256			}
257
258			public static function AC3serviceTypeLookup($bsmod, $acmod)
259			{
260			static $lookup = [
261			0 => 'main audio service: complete main (CM)',
262			1 => 'main audio service: music and effects (ME)',
263			2 => 'associated service: visually impaired (VI)',
264			3 => 'associated service: hearing impaired (HI)',
265			4 => 'associated service: dialogue (D)',
266			5 => 'associated service: commentary (C)',
267			6 => 'associated service: emergency (E)',
268			7 => 'main audio service: karaoke'
269			];
270
271			if (7 == $bsmod && 1 == $acmod) {
272			return 'associated service: voice over (VO)';
273			}
274
275			return (isset($lookup[$bsmod]) ? $lookup[$bsmod] : false);
276			}
277
278			public static function AC3audioCodingModeLookup($acmod)
279			{
280			// array (channel configuration, # channels (not incl LFE), channel order)
281			static $lookup = [
282			0 => ['channel_config' => '1+1', 'num_channels' => 2, 'channel_order' => 'Ch1,Ch2'],
283			1 => ['channel_config' => '1/0', 'num_channels' => 1, 'channel_order' => 'C'],
284			2 => ['channel_config' => '2/0', 'num_channels' => 2, 'channel_order' => 'L,R'],
285			3 => ['channel_config' => '3/0', 'num_channels' => 3, 'channel_order' => 'L,C,R'],
286			4 => ['channel_config' => '2/1', 'num_channels' => 3, 'channel_order' => 'L,R,S'],
287			5 => ['channel_config' => '3/1', 'num_channels' => 4, 'channel_order' => 'L,C,R,S'],
288			6 => ['channel_config' => '2/2', 'num_channels' => 4, 'channel_order' => 'L,R,SL,SR'],
289			7 => ['channel_config' => '3/2', 'num_channels' => 5, 'channel_order' => 'L,C,R,SL,SR']
290			];
291			return (isset($lookup[$acmod]) ? $lookup[$acmod] : false);
292			}
293
294			public static function AC3centerMixLevelLookup($cmixlev)
295			{
296			static $lookup;
297			if (!@$lookup) {
298			$lookup = [
299			0 => pow(2, -3.0 / 6), // 0.707 (�3.0 dB)
300			1 => pow(2, -4.5 / 6), // 0.595 (�4.5 dB)
301			2 => pow(2, -6.0 / 6), // 0.500 (�6.0 dB)
302			3 => 'reserved'
303			];
304			}
305			return (isset($lookup[$cmixlev]) ? $lookup[$cmixlev] : false);
306			}
307
308			public static function AC3surroundMixLevelLookup($surmixlev)
309			{
310			static $lookup;
311			if (!@$lookup) {
312			$lookup = [
313			0 => pow(2, -3.0 / 6),
314			1 => pow(2, -6.0 / 6),
315			2 => 0,
316			3 => 'reserved'
317			];
318			}
319			return (isset($lookup[$surmixlev]) ? $lookup[$surmixlev] : false);
320			}
321
322			public static function AC3dolbySurroundModeLookup($dsurmod)
323			{
324			static $lookup = [
325			0 => 'not indicated',
326			1 => 'Not Dolby Surround encoded',
327			2 => 'Dolby Surround encoded',
328			3 => 'reserved'
329			];
330			return (isset($lookup[$dsurmod]) ? $lookup[$dsurmod] : false);
331			}
332
333			public static function AC3channelsEnabledLookup($acmod, $lfeon)
334			{
335			return [
336			'ch1' => 0 == $acmod,
337			'ch2' => 0 == $acmod,
338			'left' => $acmod > 1,
339			'right' => $acmod > 1,
340			'center' => (bool)($acmod & 0x01),
341			'surround_mono' => 4 == $acmod \|\| 5 == $acmod,
342			'surround_left' => 6 == $acmod \|\| 7 == $acmod,
343			'surround_right' => 6 == $acmod \|\| 7 == $acmod,
344			'lfe' => $lfeon
345			];
346			}
347
348			public static function AC3heavyCompression($compre)
349			{
350			// The first four bits indicate gain changes in 6.02dB increments which can be
351			// implemented with an arithmetic shift operation. The following four bits
352			// indicate linear gain changes, and require a 5-bit multiply.
353			// We will represent the two 4-bit fields of compr as follows:
354			// X0 X1 X2 X3 . Y4 Y5 Y6 Y7
355			// The meaning of the X values is most simply described by considering X to represent a 4-bit
356			// signed integer with values from �8 to +7. The gain indicated by X is then (X + 1) * 6.02 dB. The
357			// following table shows this in detail.
358
359			// Meaning of 4 msb of compr
360			// 7 +48.16 dB
361			// 6 +42.14 dB
362			// 5 +36.12 dB
363			// 4 +30.10 dB
364			// 3 +24.08 dB
365			// 2 +18.06 dB
366			// 1 +12.04 dB
367			// 0 +6.02 dB
368			// -1 0 dB
369			// -2 �6.02 dB
370			// -3 �12.04 dB
371			// -4 �18.06 dB
372			// -5 �24.08 dB
373			// -6 �30.10 dB
374			// -7 �36.12 dB
375			// -8 �42.14 dB
376
377			$fourbit = str_pad(decbin(($compre & 0xF0) >> 4), 4, '0', STR_PAD_LEFT);
378			if ('1' == $fourbit{0}) {
379			$log_gain = -8 + bindec(substr($fourbit, 1));
380			} else {
381			$log_gain = bindec(substr($fourbit, 1));
382			}
383			$log_gain = ($log_gain + 1) * (20 * log10(2));
384
385			// The value of Y is a linear representation of a gain change of up to �6 dB. Y is considered to
386			// be an unsigned fractional integer, with a leading value of 1, or: 0.1 Y4 Y5 Y6 Y7 (base 2). Y can
387			// represent values between 0.111112 (or 31/32) and 0.100002 (or 1/2). Thus, Y can represent gain
388			// changes from �0.28 dB to �6.02 dB.
389
390			$lin_gain = (16 + ($compre & 0x0F)) / 32;
391
392			// The combination of X and Y values allows compr to indicate gain changes from
393			// 48.16 � 0.28 = +47.89 dB, to
394			// �42.14 � 6.02 = �48.16 dB.
395
396			return $log_gain - $lin_gain;
397			}
398
399			public static function AC3roomTypeLookup($roomtyp)
400			{
401			static $lookup = [
402			0 => 'not indicated',
403			1 => 'large room, X curve monitor',
404			2 => 'small room, flat monitor',
405			3 => 'reserved'
406			];
407			return (isset($lookup[$roomtyp]) ? $lookup[$roomtyp] : false);
408			}
409
410			public static function AC3frameSizeLookup($frmsizecod, $fscod)
411			{
412			$padding = (bool)($frmsizecod % 2);
413			$frame_size_id = floor($frmsizecod / 2);
414
415			static $lookup = [
416			0 => [128, 138, 192],
417			1 => [40, 160, 174, 240],
418			2 => [48, 192, 208, 288],
419			3 => [56, 224, 242, 336],
420			4 => [64, 256, 278, 384],
421			5 => [80, 320, 348, 480],
422			6 => [96, 384, 416, 576],
423			7 => [112, 448, 486, 672],
424			8 => [128, 512, 556, 768],
425			9 => [160, 640, 696, 960],
426			10 => [192, 768, 834, 1152],
427			11 => [224, 896, 974, 1344],
428			12 => [256, 1024, 1114, 1536],
429			13 => [320, 1280, 1392, 1920],
430			14 => [384, 1536, 1670, 2304],
431			15 => [448, 1792, 1950, 2688],
432			16 => [512, 2048, 2228, 3072],
433			17 => [576, 2304, 2506, 3456],
434			18 => [640, 2560, 2786, 3840]
435			];
436			if ((1 == $fscod) && $padding) {
437			// frame lengths are padded by 1 word (16 bits) at 44100
438			$lookup[$frmsizecod] += 2;
439			}
440			return (isset($lookup[$frame_size_id][$fscod]) ? $lookup[$frame_size_id][$fscod] : false);
441			}
442
443			public static function AC3bitrateLookup($frmsizecod)
444			{
445			static $lookup = [
446			0 => 32000,
447			1 => 40000,
448			2 => 48000,
449			3 => 56000,
450			4 => 64000,
451			5 => 80000,
452			6 => 96000,
453			7 => 112000,
454			8 => 128000,
455			9 => 160000,
456			10 => 192000,
457			11 => 224000,
458			12 => 256000,
459			13 => 320000,
460			14 => 384000,
461			15 => 448000,
462			16 => 512000,
463			17 => 576000,
464			18 => 640000
465			];
466			$frame_size_id = floor($frmsizecod / 2);
467			return (isset($lookup[$frame_size_id]) ? $lookup[$frame_size_id] : false);
468			}
469
470			}
471
472
473

mambax7 / xoopseditors

getid3_ac3::AC3dolbySurroundModeLookup() A last analyzed 2022-06-12 05:55 UTC

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getid3_ac3::AC3dolbySurroundModeLookup() A
last analyzed 2022-06-12 05:55 UTC