Файл: core/PEAR/Ogg/Theora.php
Строк: 164
<?php
/* vim: set expandtab tabstop=4 shiftwidth=4: */
// +----------------------------------------------------------------------------+
// | File_Ogg PEAR Package for Accessing Ogg Bitstreams |
// | Copyright (c) 2005-2007 |
// | David Grant <david@grant.org.uk> |
// | Tim Starling <tstarling@wikimedia.org> |
// +----------------------------------------------------------------------------+
// | This library is free software; you can redistribute it and/or |
// | modify it under the terms of the GNU Lesser General Public |
// | License as published by the Free Software Foundation; either |
// | version 2.1 of the License, or (at your option) any later version. |
// | |
// | This library is distributed in the hope that it will be useful, |
// | but WITHOUT ANY WARRANTY; without even the implied warranty of |
// | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
// | Lesser General Public License for more details. |
// | |
// | You should have received a copy of the GNU Lesser General Public |
// | License along with this library; if not, write to the Free Software |
// | Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
// +----------------------------------------------------------------------------+
require_once('Bitstream.php');
define( 'OGG_THEORA_IDENTIFICATION_HEADER', 0x80 );
define( 'OGG_THEORA_COMMENTS_HEADER', 0x81 );
define( 'OGG_THEORA_IDENTIFICATION_PAGE_OFFSET', 0 );
define( 'OGG_THEORA_COMMENTS_PAGE_OFFSET', 1 );
/**
* @author David Grant <david@grant.org.uk>, Tim Starling <tstarling@wikimedia.org>
* @category File
* @copyright David Grant <david@grant.org.uk>, Tim Starling <tstarling@wikimedia.org>
* @license http://www.gnu.org/copyleft/lesser.html GNU LGPL
* @link http://pear.php.net/package/File_Ogg
* @link http://www.xiph.org/theora/
* @package File_Ogg
* @version CVS: $Id: Theora.php,v 1.10 2008/01/31 04:41:44 tstarling Exp $
*/
class File_Ogg_Theora extends File_Ogg_Media
{
/**
* @access private
*/
function File_Ogg_Theora($streamSerial, $streamData, $filePointer)
{
File_Ogg_Media::File_Ogg_Media($streamSerial, $streamData, $filePointer);
$this->_decodeIdentificationHeader();
$this->_decodeCommentsHeader();
// Calculate length
// First make some "numeric strings"
// These might not fit into PHP's integer type, but they will fit into
// the 53-bit mantissa of a double-precision number
$topWord = floatval( '0x' . substr( $this->_lastGranulePos, 0, 8 ) );
$bottomWord = floatval( '0x' . substr( $this->_lastGranulePos, 8, 8 ) );
// Calculate the keyframe position by shifting right by KFGSHIFT
// We don't use PHP's shift operators because they're terribly broken
// This is made slightly simpler by the fact that KFGSHIFT < 32
$keyFramePos = $topWord / pow(2, $this->_kfgShift - 32) +
floor( $bottomWord / pow(2, $this->_kfgShift) );
// Calculate the frame offset by masking off the top 64-KFGSHIFT bits
// This requires a bit of floating point trickery
$offset = fmod( $bottomWord, pow(2, $this->_kfgShift) );
// They didn't teach you that one at school did they?
// Now put it together with the frame rate to calculate length in seconds
$this->_streamLength = ( $keyFramePos + $offset ) / $this->_frameRate;
$this->_avgBitrate = $this->_streamLength ? ($this->_streamSize * 8) / $this->_streamLength : 0;
}
/**
* Get the 6-byte identification string expected in the common header
*/
function getIdentificationString()
{
return OGG_STREAM_CAPTURE_THEORA;
}
/**
* Parse the identification header in a Theora stream.
* @access private
*/
function _decodeIdentificationHeader()
{
$this->_decodeCommonHeader(OGG_THEORA_IDENTIFICATION_HEADER, OGG_THEORA_IDENTIFICATION_PAGE_OFFSET);
$h = File_Ogg::_readBigEndian( $this->_filePointer, array(
'VMAJ' => 8,
'VMIN' => 8,
'VREV' => 8,
'FMBW' => 16,
'FMBH' => 16,
'PICW' => 24,
'PICH' => 24,
'PICX' => 8,
'PICY' => 8,
'FRN' => 32,
'FRD' => 32,
'PARN' => 24,
'PARD' => 24,
'CS' => 8,
'NOMBR' => 24,
'QUAL' => 6,
'KFGSHIFT' => 5,
'PF' => 2));
if ( !$h ) {
throw new PEAR_Exception("Stream is undecodable due to a truncated header.", OGG_ERROR_UNDECODABLE);
}
// Theora version
// Seems overly strict but this is what the spec says
// VREV is for backwards-compatible changes, apparently
if ( $h['VMAJ'] != 3 || $h['VMIN'] != 2 ) {
throw new PEAR_Exception("Stream is undecodable due to an invalid theora version.", OGG_ERROR_UNDECODABLE);
}
$this->_theoraVersion = "{$h['VMAJ']}.{$h['VMIN']}.{$h['VREV']}";
// Frame height/width
if ( !$h['FMBW'] || !$h['FMBH'] ) {
throw new PEAR_Exception("Stream is undecodable because it has frame size of zero.", OGG_ERROR_UNDECODABLE);
}
$this->_frameWidth = $h['FMBW'] * 16;
$this->_frameHeight = $h['FMBH'] * 16;
// Picture height/width
if ( $h['PICW'] > $this->_frameWidth || $h['PICH'] > $this->_frameHeight ) {
throw new PEAR_Exception("Stream is undecodable because the picture width is greater than the frame width.", OGG_ERROR_UNDECODABLE);
}
$this->_pictureWidth = $h['PICW'];
$this->_pictureHeight = $h['PICH'];
// Picture offset
$this->_offsetX = $h['PICX'];
$this->_offsetY = $h['PICY'];
// Frame rate
$this->_frameRate = $h['FRD'] == 0 ? 0 : $h['FRN'] / $h['FRD'];
// Physical aspect ratio
if ( !$h['PARN'] || !$h['PARD'] ) {
$this->_physicalAspectRatio = 1;
} else {
$this->_physicalAspectRatio = $h['PARN'] / $h['PARD'];
}
// Color space
$colorSpaces = array(
0 => 'Undefined',
1 => 'Rec. 470M',
2 => 'Rec. 470BG',
);
if ( isset( $colorSpaces[$h['CS']] ) ) {
$this->_colorSpace = $colorSpaces[$h['CS']];
} else {
$this->_colorSpace = 'Unknown (reserved)';
}
$this->_nomBitrate = $h['NOMBR'];
$this->_quality = $h['QUAL'];
$this->_kfgShift = $h['KFGSHIFT'];
$pixelFormats = array(
0 => '4:2:0',
1 => 'Unknown (reserved)',
2 => '4:2:2',
3 => '4:4:4',
);
$this->_pixelFormat = $pixelFormats[$h['PF']];
switch ( $h['PF'] ) {
case 0:
$h['NSBS'] =
floor( ($h['FMBW'] + 1) / 2 ) *
floor( ($h['FMBH'] + 1) / 2 ) + 2 *
floor( ($h['FMBW'] + 3) / 4 ) *
floor( ($h['FMBH'] + 3) / 4 );
$h['NBS'] = 6 * $h['FMBW'] * $h['FMBH'];
break;
case 2:
$h['NSBS'] =
floor( ($h['FMBW'] + 1) / 2 ) *
floor( ($h['FMBH'] + 1) / 2 ) + 2 *
floor( ($h['FMBW'] + 3) / 4 ) *
floor( ($h['FMBH'] + 1) / 2 );
$h['NBS'] = 8 * $h['FMBW'] * $h['FMBH'];
break;
case 3:
$h['NSBS'] =
3 * floor( ($h['FMBW'] + 1) / 2 ) *
floor( ($h['FMBH'] + 1) / 2 );
$h['NBS'] = 12 * $h['FMBW'] * $h['FMBH'];
break;
default:
$h['NSBS'] = $h['NBS'] = 0;
}
$h['NMBS'] = $h['FMBW'] * $h['FMBH'];
$this->_idHeader = $h;
}
/**
* Get an associative array containing header information about the stream
* @access public
* @return array
*/
function getHeader() {
return $this->_idHeader;
}
/**
* Get a short string describing the type of the stream
* @return string
*/
function getType() {
return 'Theora';
}
/**
* Decode the comments header
* @access private
*/
function _decodeCommentsHeader()
{
$this->_decodeCommonHeader(OGG_THEORA_COMMENTS_HEADER, OGG_THEORA_COMMENTS_PAGE_OFFSET);
$this->_decodeBareCommentsHeader();
}
}
?>