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<?php
/////////////////////////////////////////////////////////////////
/// getID3() by James Heinrich <info@getid3.org> //
// available at https://github.com/JamesHeinrich/getID3 //
// or https://www.getid3.org //
// or http://getid3.sourceforge.net //
// see readme.txt for more details //
/////////////////////////////////////////////////////////////////
// //
// module.graphic.gif.php //
// module for analyzing GIF Image files //
// dependencies: NONE //
// ///
/////////////////////////////////////////////////////////////////
/**
* @link https://www.w3.org/Graphics/GIF/spec-gif89a.txt
* @link http://www.matthewflickinger.com/lab/whatsinagif/bits_and_bytes.asp
* @link http://www.vurdalakov.net/misc/gif/netscape-looping-application-extension
*/
if (!defined('GETID3_INCLUDEPATH')) { // prevent path-exposing attacks that access modules directly on public webservers
exit;
}
class getid3_gif extends getid3_handler
{
/**
* @return bool
*/
public function Analyze() {
$info = &$this->getid3->info;
$info['fileformat'] = 'gif';
$info['video']['dataformat'] = 'gif';
$info['video']['lossless'] = true;
$info['video']['pixel_aspect_ratio'] = (float) 1;
$this->fseek($info['avdataoffset']);
$GIFheader = $this->fread(13);
$offset = 0;
$info['gif']['header']['raw']['identifier'] = substr($GIFheader, $offset, 3);
$offset += 3;
$magic = 'GIF';
if ($info['gif']['header']['raw']['identifier'] != $magic) {
$this->error('Expecting "'.getid3_lib::PrintHexBytes($magic).'" at offset '.$info['avdataoffset'].', found "'.getid3_lib::PrintHexBytes($info['gif']['header']['raw']['identifier']).'"');
unset($info['fileformat']);
unset($info['gif']);
return false;
}
//if (!$this->getid3->option_extra_info) {
// $this->warning('GIF Extensions and Global Color Table not returned due to !getid3->option_extra_info');
//}
$info['gif']['header']['raw']['version'] = substr($GIFheader, $offset, 3);
$offset += 3;
$info['gif']['header']['raw']['width'] = getid3_lib::LittleEndian2Int(substr($GIFheader, $offset, 2));
$offset += 2;
$info['gif']['header']['raw']['height'] = getid3_lib::LittleEndian2Int(substr($GIFheader, $offset, 2));
$offset += 2;
$info['gif']['header']['raw']['flags'] = getid3_lib::LittleEndian2Int(substr($GIFheader, $offset, 1));
$offset += 1;
$info['gif']['header']['raw']['bg_color_index'] = getid3_lib::LittleEndian2Int(substr($GIFheader, $offset, 1));
$offset += 1;
$info['gif']['header']['raw']['aspect_ratio'] = getid3_lib::LittleEndian2Int(substr($GIFheader, $offset, 1));
$offset += 1;
$info['video']['resolution_x'] = $info['gif']['header']['raw']['width'];
$info['video']['resolution_y'] = $info['gif']['header']['raw']['height'];
$info['gif']['version'] = $info['gif']['header']['raw']['version'];
$info['gif']['header']['flags']['global_color_table'] = (bool) ($info['gif']['header']['raw']['flags'] & 0x80);
if ($info['gif']['header']['raw']['flags'] & 0x80) {
// Number of bits per primary color available to the original image, minus 1
$info['gif']['header']['bits_per_pixel'] = 3 * ((($info['gif']['header']['raw']['flags'] & 0x70) >> 4) + 1);
} else {
$info['gif']['header']['bits_per_pixel'] = 0;
}
$info['gif']['header']['flags']['global_color_sorted'] = (bool) ($info['gif']['header']['raw']['flags'] & 0x40);
if ($info['gif']['header']['flags']['global_color_table']) {
// the number of bytes contained in the Global Color Table. To determine that
// actual size of the color table, raise 2 to [the value of the field + 1]
$info['gif']['header']['global_color_size'] = pow(2, ($info['gif']['header']['raw']['flags'] & 0x07) + 1);
$info['video']['bits_per_sample'] = ($info['gif']['header']['raw']['flags'] & 0x07) + 1;
} else {
$info['gif']['header']['global_color_size'] = 0;
}
if ($info['gif']['header']['raw']['aspect_ratio'] != 0) {
// Aspect Ratio = (Pixel Aspect Ratio + 15) / 64
$info['gif']['header']['aspect_ratio'] = ($info['gif']['header']['raw']['aspect_ratio'] + 15) / 64;
}
if ($info['gif']['header']['flags']['global_color_table']) {
$GIFcolorTable = $this->fread(3 * $info['gif']['header']['global_color_size']);
if ($this->getid3->option_extra_info) {
$offset = 0;
for ($i = 0; $i < $info['gif']['header']['global_color_size']; $i++) {
$red = getid3_lib::LittleEndian2Int(substr($GIFcolorTable, $offset++, 1));
$green = getid3_lib::LittleEndian2Int(substr($GIFcolorTable, $offset++, 1));
$blue = getid3_lib::LittleEndian2Int(substr($GIFcolorTable, $offset++, 1));
$info['gif']['global_color_table'][$i] = (($red << 16) | ($green << 8) | ($blue));
$info['gif']['global_color_table_rgb'][$i] = sprintf('%02X%02X%02X', $red, $green, $blue);
}
}
}
// Image Descriptor
$info['gif']['animation']['animated'] = false;
while (!feof($this->getid3->fp)) {
$NextBlockTest = $this->fread(1);
switch ($NextBlockTest) {
/*
case ',': // ',' - Image separator character
$ImageDescriptorData = $NextBlockTest.$this->fread(9);
$ImageDescriptor = array();
$ImageDescriptor['image_left'] = getid3_lib::LittleEndian2Int(substr($ImageDescriptorData, 1, 2));
$ImageDescriptor['image_top'] = getid3_lib::LittleEndian2Int(substr($ImageDescriptorData, 3, 2));
$ImageDescriptor['image_width'] = getid3_lib::LittleEndian2Int(substr($ImageDescriptorData, 5, 2));
$ImageDescriptor['image_height'] = getid3_lib::LittleEndian2Int(substr($ImageDescriptorData, 7, 2));
$ImageDescriptor['flags_raw'] = getid3_lib::LittleEndian2Int(substr($ImageDescriptorData, 9, 1));
$ImageDescriptor['flags']['use_local_color_map'] = (bool) ($ImageDescriptor['flags_raw'] & 0x80);
$ImageDescriptor['flags']['image_interlaced'] = (bool) ($ImageDescriptor['flags_raw'] & 0x40);
$info['gif']['image_descriptor'][] = $ImageDescriptor;
if ($ImageDescriptor['flags']['use_local_color_map']) {
$this->warning('This version of getID3() cannot parse local color maps for GIFs');
return true;
}
$RasterData = array();
$RasterData['code_size'] = getid3_lib::LittleEndian2Int($this->fread(1));
$RasterData['block_byte_count'] = getid3_lib::LittleEndian2Int($this->fread(1));
$info['gif']['raster_data'][count($info['gif']['image_descriptor']) - 1] = $RasterData;
$CurrentCodeSize = $RasterData['code_size'] + 1;
for ($i = 0; $i < pow(2, $RasterData['code_size']); $i++) {
$DefaultDataLookupTable[$i] = chr($i);
}
$DefaultDataLookupTable[pow(2, $RasterData['code_size']) + 0] = ''; // Clear Code
$DefaultDataLookupTable[pow(2, $RasterData['code_size']) + 1] = ''; // End Of Image Code
$NextValue = $this->GetLSBits($CurrentCodeSize);
echo 'Clear Code: '.$NextValue.'<BR>';
$NextValue = $this->GetLSBits($CurrentCodeSize);
echo 'First Color: '.$NextValue.'<BR>';
$Prefix = $NextValue;
$i = 0;
while ($i++ < 20) {
$NextValue = $this->GetLSBits($CurrentCodeSize);
echo $NextValue.'<br>';
}
echo 'escaping<br>';
return true;
break;
*/
case '!':
// GIF Extension Block
$ExtensionBlockData = $NextBlockTest.$this->fread(2);
$ExtensionBlock = array();
$ExtensionBlock['function_code'] = getid3_lib::LittleEndian2Int(substr($ExtensionBlockData, 1, 1));
$ExtensionBlock['byte_length'] = getid3_lib::LittleEndian2Int(substr($ExtensionBlockData, 2, 1));
$ExtensionBlock['data'] = (($ExtensionBlock['byte_length'] > 0) ? $this->fread($ExtensionBlock['byte_length']) : null);
switch ($ExtensionBlock['function_code']) {
case 0xFF:
// Application Extension
if ($ExtensionBlock['byte_length'] != 11) {
$this->warning('Expected block size of the Application Extension is 11 bytes, found '.$ExtensionBlock['byte_length'].' at offset '.$this->ftell());
break;
}
if (substr($ExtensionBlock['data'], 0, 11) !== 'NETSCAPE2.0'
&& substr($ExtensionBlock['data'], 0, 11) !== 'ANIMEXTS1.0'
) {
$this->warning('Ignoring unsupported Application Extension '.substr($ExtensionBlock['data'], 0, 11));
break;
}
// Netscape Application Block (NAB)
$ExtensionBlock['data'] .= $this->fread(4);
if (substr($ExtensionBlock['data'], 11, 2) == "\x03\x01") {
$info['gif']['animation']['animated'] = true;
$info['gif']['animation']['loop_count'] = getid3_lib::LittleEndian2Int(substr($ExtensionBlock['data'], 13, 2));
} else {
$this->warning('Expecting 03 01 at offset '.($this->ftell() - 4).', found "'.getid3_lib::PrintHexBytes(substr($ExtensionBlock['data'], 11, 2)).'"');
}
break;
}
if ($this->getid3->option_extra_info) {
$info['gif']['extension_blocks'][] = $ExtensionBlock;
}
break;
case ';':
$info['gif']['terminator_offset'] = $this->ftell() - 1;
// GIF Terminator
break;
default:
break;
}
}
return true;
}
/**
* @param int $bits
*
* @return float|int
*/
public function GetLSBits($bits) {
static $bitbuffer = '';
while (strlen($bitbuffer) < $bits) {
$bitbuffer = str_pad(decbin(ord($this->fread(1))), 8, '0', STR_PAD_LEFT).$bitbuffer;
}
$value = bindec(substr($bitbuffer, 0 - $bits));
$bitbuffer = substr($bitbuffer, 0, 0 - $bits);
return $value;
}
}
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