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RiffExtractor.php
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RiffExtractor.php
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<?php
/**
* @license GPL-2.0-or-later
* @author Bryan Tong Minh
*/
/**
* Extractor for the Resource Interchange File Format
*
* @ingroup Media
*/
class RiffExtractor {
/**
* @param string $filename
* @param int $maxChunks
* @return array|false
*/
public static function findChunksFromFile( $filename, $maxChunks = -1 ) {
$file = fopen( $filename, 'rb' );
$info = self::findChunks( $file, $maxChunks );
fclose( $file );
return $info;
}
/**
* @param resource $file
* @param int $maxChunks
* @return array|false
*/
public static function findChunks( $file, $maxChunks = -1 ) {
$riff = fread( $file, 4 );
if ( $riff !== 'RIFF' ) {
return false;
}
// Next four bytes are fileSize
$fileSize = fread( $file, 4 );
if ( !$fileSize || strlen( $fileSize ) != 4 ) {
return false;
}
// Next four bytes are the FourCC
$fourCC = fread( $file, 4 );
if ( !$fourCC || strlen( $fourCC ) != 4 ) {
return false;
}
// Create basic info structure
$info = [
'fileSize' => self::extractUInt32( $fileSize ),
'fourCC' => $fourCC,
'chunks' => [],
];
$numberOfChunks = 0;
// Find out the chunks
while ( !feof( $file ) && !( $numberOfChunks >= $maxChunks && $maxChunks >= 0 ) ) {
$chunkStart = ftell( $file );
$chunkFourCC = fread( $file, 4 );
if ( !$chunkFourCC || strlen( $chunkFourCC ) != 4 ) {
return $info;
}
$chunkSize = fread( $file, 4 );
if ( !$chunkSize || strlen( $chunkSize ) != 4 ) {
return $info;
}
$intChunkSize = self::extractUInt32( $chunkSize );
// Add chunk info to the info structure
$info['chunks'][] = [
'fourCC' => $chunkFourCC,
'start' => $chunkStart,
'size' => $intChunkSize
];
// Uneven chunks have padding bytes
$padding = $intChunkSize % 2;
// Seek to the next chunk
fseek( $file, $intChunkSize + $padding, SEEK_CUR );
}
return $info;
}
/**
* Extract a little-endian uint32 from a 4 byte string
* @param string $string 4-byte string
* @return int
*/
public static function extractUInt32( $string ) {
return unpack( 'V', $string )[1];
}
}

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text/x-php
Expires
Sat, Oct 3, 19:31 (2 d, 14 h ago)
Storage Engine
local-disk
Storage Format
Raw Data
Storage Handle
a6/0a/875906e526f9b78ec41c75f8e24e
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RiffExtractor.php (2 KB)

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