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<?php
/**
* PHP Reader Library
*
* Copyright (c) 2008 The PHP Reader Project Workgroup. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - Neither the name of the project workgroup nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* @package php-reader
* @subpackage ISO 14496
* @copyright Copyright (c) 2008 The PHP Reader Project Workgroup
* @license http://code.google.com/p/php-reader/wiki/License New BSD License
* @version $Id: SUBS.php 92 2008-05-10 13:43:14Z svollbehr $
*/
/**#@+ @ignore */
require_once("ISO14496/Box/Full.php");
/**#@-*/
/**
* The <i>Sub-Sample Information Box</i> is designed to contain sub-sample
* information.
*
* A sub-sample is a contiguous range of bytes of a sample. The specific
* definition of a sub-sample shall be supplied for a given coding system (e.g.
* for ISO/IEC 14496-10, Advanced Video Coding). In the absence of such a
* specific definition, this box shall not be applied to samples using that
* coding system.
*
* If subsample_count is 0 for any entry, then those samples have no subsample
* information and no array follows. The table is sparsely coded; the table
* identifies which samples have sub-sample structure by recording the
* difference in sample-number between each entry. The first entry in the table
* records the sample number of the first sample having sub-sample information.
*
* Note: It is possible to combine subsamplePriority and discardable such that
* when subsamplePriority is smaller than a certain value, discardable is set to
* 1. However, since different systems may use different scales of priority
* values, to separate them is safe to have a clean solution for discardable
* sub-samples.
*
* @package php-reader
* @subpackage ISO 14496
* @author Sven Vollbehr <svollbehr@gmail.com>
* @copyright Copyright (c) 2008 The PHP Reader Project Workgroup
* @license http://code.google.com/p/php-reader/wiki/License New BSD License
* @version $Rev: 92 $
*/
final class ISO14496_Box_SUBS extends ISO14496_Box_Full
{
/** @var Array */
private $_subSampleTable = array();
/**
* Constructs the class with given parameters and reads box related data from
* the ISO Base Media file.
*
* @param Reader $reader The reader object.
*/
public function __construct($reader, &$options = array())
{
parent::__construct($reader, $options);
$entryCount = $this->_reader->readUInt32BE();
for ($i = 0; $i < $entryCount; $i++) {
$entry = array();
$entry["sampleDelta"] = $this->_reader->readUInt32BE();
$entry["subsamples"] = array();
if (($subsampleCount = $this->_reader->readUInt16BE()) > 0) {
for ($j = 0; $j < $subsampleCount; $j++) {
$subsample = array();
if ($this->getVersion() == 1)
$subsample["subsampleSize"] = $this->_reader->readUInt32BE();
else
$subsample["subsampleSize"] = $this->_reader->readUInt16BE();
$subsample["subsamplePriority"] = $this->_reader->readInt8();
$subsample["discardable"] = $this->_reader->readInt8();
$this->_reader->skip(4);
$entry["subsamples"][] = $subsample;
}
$this->_subSampleTable[] = $entry;
}
}
}
/**
* Returns an array of values. Each entry is an array containing the following
* keys.
* o sampleDelta -- an integer that specifies the sample number of the
* sample having sub-sample structure. It is coded as the difference
* between the desired sample number, and the sample number indicated in
* the previous entry. If the current entry is the first entry, the value
* indicates the sample number of the first sample having sub-sample
* information, that is, the value is the difference between the sample
* number and zero (0).
* o subsamples -- an array of subsample arrays, each containing the
* following keys.
* o subsampleSize -- an integer that specifies the size, in bytes, of
* the current sub-sample.
* o subsamplePriority -- an integer specifying the degradation priority
* for each sub-sample. Higher values of subsamplePriority, indicate
* sub-samples which are important to, and have a greater impact on,
* the decoded quality.
* o discardable -- equal to 0 means that the sub-sample is required to
* decode the current sample, while equal to 1 means the sub-sample is
* not required to decode the current sample but may be used for
* enhancements, e.g., the sub-sample consists of supplemental
* enhancement information (SEI) messages.
*
* @return Array
*/
public function getSubSampleTable()
{
return $this->_subSampleTable;
}
}
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