getid3_ac3::Analyze()

Complexity

Conditions	23
Paths	> 20000

Size

Total Lines

222

Duplication

Lines	0
Ratio	0 %

Importance

Changes	1
Bugs	0	Features	0

<?php
    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'] = array ();
        $info_ac3         = &$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);

$ac3_header was never initialized. Although not strictly required by PHP, it is generally a good practice to add $ac3_header = array(); before regardless.

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

        if ($info_ac3_raw['synchinfo']['synchword'] != "\x0B\x77") {
            throw new getid3_exception('Expecting "\x0B\x77" at offset '.$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 ($info_ac3_raw_bsi['acmod'] == 0x02) {
            // 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'] = $ac3_header['bsi']{$offset++} == '1';
        $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'] = $ac3_header['bsi']{$offset++} == '1';
        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'] = $ac3_header['bsi']{$offset++} == '1';
        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'] = $ac3_header['bsi']{$offset++} == '1';
        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 ($info_ac3_raw_bsi['acmod'] == 0x00) {
            // 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'] = $ac3_header['bsi']{$offset++} == '1';
            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'] = $ac3_header['bsi']{$offset++} == '1';
            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'] = $ac3_header['bsi']{$offset++} == '1';
            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'] = $ac3_header['bsi']{$offset++} == '1';

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

        $info_ac3_raw_bsi['timecode1_flag'] = $ac3_header['bsi']{$offset++} == '1';
        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'] = $ac3_header['bsi']{$offset++} == '1';
        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'] = $ac3_header['bsi']{$offset++} == '1';
        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;
    }
?>

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