99 lines
2.6 KiB
PHP
99 lines
2.6 KiB
PHP
<?php
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/**
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* Extractor for the Resource Interchange File Format
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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* @author Bryan Tong Minh
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* @ingroup Media
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*/
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class RiffExtractor {
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public static function findChunksFromFile( $filename, $maxChunks = -1 ) {
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$file = fopen( $filename, 'rb' );
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$info = self::findChunks( $file, $maxChunks );
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fclose( $file );
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return $info;
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}
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public static function findChunks( $file, $maxChunks = -1 ) {
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$riff = fread( $file, 4 );
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if ( $riff !== 'RIFF' ) {
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return false;
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}
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// Next four bytes are fileSize
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$fileSize = fread( $file, 4 );
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if ( !$fileSize || strlen( $fileSize ) != 4 ) {
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return false;
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}
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// Next four bytes are the FourCC
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$fourCC = fread( $file, 4 );
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if ( !$fourCC || strlen( $fourCC ) != 4 ) {
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return false;
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}
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// Create basic info structure
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$info = [
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'fileSize' => self::extractUInt32( $fileSize ),
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'fourCC' => $fourCC,
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'chunks' => [],
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];
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$numberOfChunks = 0;
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// Find out the chunks
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while ( !feof( $file ) && !( $numberOfChunks >= $maxChunks && $maxChunks >= 0 ) ) {
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$chunkStart = ftell( $file );
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$chunkFourCC = fread( $file, 4 );
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if ( !$chunkFourCC || strlen( $chunkFourCC ) != 4 ) {
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return $info;
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}
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$chunkSize = fread( $file, 4 );
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if ( !$chunkSize || strlen( $chunkSize ) != 4 ) {
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return $info;
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}
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$intChunkSize = self::extractUInt32( $chunkSize );
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// Add chunk info to the info structure
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$info['chunks'][] = [
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'fourCC' => $chunkFourCC,
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'start' => $chunkStart,
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'size' => $intChunkSize
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];
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// Uneven chunks have padding bytes
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$padding = $intChunkSize % 2;
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// Seek to the next chunk
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fseek( $file, $intChunkSize + $padding, SEEK_CUR );
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}
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return $info;
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}
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/**
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* Extract a little-endian uint32 from a 4 byte string
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* @param string $string 4-byte string
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* @return int
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*/
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public static function extractUInt32( $string ) {
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return unpack( 'V', $string )[1];
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}
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}
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