PHP getid3_lib::trunc方法代碼示例

 static function Float2BinaryDecimal($floatvalue)
 {
     // http://www.scri.fsu.edu/~jac/MAD3401/Backgrnd/binary.html
     $maxbits = 128;
     // to how many bits of precision should the calculations be taken?
     $intpart = getid3_lib::trunc($floatvalue);
     $floatpart = abs($floatvalue - $intpart);
     $pointbitstring = '';
     while ($floatpart != 0 && strlen($pointbitstring) < $maxbits) {
         $floatpart *= 2;
         $pointbitstring .= (string) getid3_lib::trunc($floatpart);
         $floatpart -= getid3_lib::trunc($floatpart);
     }
     $binarypointnumber = decbin($intpart) . '.' . $pointbitstring;
     return $binarypointnumber;
 }

 function Analyze()
 {
     $info =& $this->getid3->info;
     $OriginalAVdataOffset = $info['avdataoffset'];
     fseek($this->getid3->fp, $info['avdataoffset'], SEEK_SET);
     $VOCheader = fread($this->getid3->fp, 26);
     $magic = 'Creative Voice File';
     if (substr($VOCheader, 0, 19) != $magic) {
         $info['error'][] = 'Expecting "' . getid3_lib::PrintHexBytes($magic) . '" at offset ' . $info['avdataoffset'] . ', found "' . getid3_lib::PrintHexBytes(substr($VOCheader, 0, 19)) . '"';
         return false;
     }
     // shortcuts
     $thisfile_audio =& $info['audio'];
     $info['voc'] = array();
     $thisfile_voc =& $info['voc'];
     $info['fileformat'] = 'voc';
     $thisfile_audio['dataformat'] = 'voc';
     $thisfile_audio['bitrate_mode'] = 'cbr';
     $thisfile_audio['lossless'] = true;
     $thisfile_audio['channels'] = 1;
     // might be overriden below
     $thisfile_audio['bits_per_sample'] = 8;
     // might be overriden below
     // byte #     Description
     // ------     ------------------------------------------
     // 00-12      'Creative Voice File'
     // 13         1A (eof to abort printing of file)
     // 14-15      Offset of first datablock in .voc file (std 1A 00 in Intel Notation)
     // 16-17      Version number (minor,major) (VOC-HDR puts 0A 01)
     // 18-19      2's Comp of Ver. # + 1234h (VOC-HDR puts 29 11)
     $thisfile_voc['header']['datablock_offset'] = getid3_lib::LittleEndian2Int(substr($VOCheader, 20, 2));
     $thisfile_voc['header']['minor_version'] = getid3_lib::LittleEndian2Int(substr($VOCheader, 22, 1));
     $thisfile_voc['header']['major_version'] = getid3_lib::LittleEndian2Int(substr($VOCheader, 23, 1));
     do {
         $BlockOffset = ftell($this->getid3->fp);
         $BlockData = fread($this->getid3->fp, 4);
         $BlockType = ord($BlockData[0]);
         $BlockSize = getid3_lib::LittleEndian2Int(substr($BlockData, 1, 3));
         $ThisBlock = array();
         getid3_lib::safe_inc($thisfile_voc['blocktypes'][$BlockType], 1);
         switch ($BlockType) {
             case 0:
                 // Terminator
                 // do nothing, we'll break out of the loop down below
                 break;
             case 1:
                 // Sound data
                 $BlockData .= fread($this->getid3->fp, 2);
                 if ($info['avdataoffset'] <= $OriginalAVdataOffset) {
                     $info['avdataoffset'] = ftell($this->getid3->fp);
                 }
                 fseek($this->getid3->fp, $BlockSize - 2, SEEK_CUR);
                 $ThisBlock['sample_rate_id'] = getid3_lib::LittleEndian2Int(substr($BlockData, 4, 1));
                 $ThisBlock['compression_type'] = getid3_lib::LittleEndian2Int(substr($BlockData, 5, 1));
                 $ThisBlock['compression_name'] = $this->VOCcompressionTypeLookup($ThisBlock['compression_type']);
                 if ($ThisBlock['compression_type'] <= 3) {
                     $thisfile_voc['compressed_bits_per_sample'] = getid3_lib::CastAsInt(str_replace('-bit', '', $ThisBlock['compression_name']));
                 }
                 // Less accurate sample_rate calculation than the Extended block (#8) data (but better than nothing if Extended Block is not available)
                 if (empty($thisfile_audio['sample_rate'])) {
                     // SR byte = 256 - (1000000 / sample_rate)
                     $thisfile_audio['sample_rate'] = getid3_lib::trunc(1000000 / (256 - $ThisBlock['sample_rate_id']) / $thisfile_audio['channels']);
                 }
                 break;
             case 2:
                 // Sound continue
             // Sound continue
             case 3:
                 // Silence
             // Silence
             case 4:
                 // Marker
             // Marker
             case 6:
                 // Repeat
             // Repeat
             case 7:
                 // End repeat
                 // nothing useful, just skip
                 fseek($this->getid3->fp, $BlockSize, SEEK_CUR);
                 break;
             case 8:
                 // Extended
                 $BlockData .= fread($this->getid3->fp, 4);
                 //00-01  Time Constant:
                 //   Mono: 65536 - (256000000 / sample_rate)
                 // Stereo: 65536 - (256000000 / (sample_rate * 2))
                 $ThisBlock['time_constant'] = getid3_lib::LittleEndian2Int(substr($BlockData, 4, 2));
                 $ThisBlock['pack_method'] = getid3_lib::LittleEndian2Int(substr($BlockData, 6, 1));
                 $ThisBlock['stereo'] = (bool) getid3_lib::LittleEndian2Int(substr($BlockData, 7, 1));
                 $thisfile_audio['channels'] = $ThisBlock['stereo'] ? 2 : 1;
                 $thisfile_audio['sample_rate'] = getid3_lib::trunc(256000000 / (65536 - $ThisBlock['time_constant']) / $thisfile_audio['channels']);
                 break;
             case 9:
                 // data block that supersedes blocks 1 and 8. Used for stereo, 16 bit
                 $BlockData .= fread($this->getid3->fp, 12);
                 if ($info['avdataoffset'] <= $OriginalAVdataOffset) {
                     $info['avdataoffset'] = ftell($this->getid3->fp);
                 }
                 fseek($this->getid3->fp, $BlockSize - 12, SEEK_CUR);
//.........這裏部分代碼省略.........