Add support for ISO base media file format
git-svn-id: http://php-reader.googlecode.com/svn/trunk@85 51a70ab9-7547-0410-9469-37e369ee0574
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svollbehr
134
src/ISO14496/Box/ILOC.php
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134
src/ISO14496/Box/ILOC.php
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<?php
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/**
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* PHP Reader Library
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*
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* Copyright (c) 2008 The PHP Reader Project Workgroup. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* - Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* - Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* - Neither the name of the project workgroup nor the names of its
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* contributors may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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* @package php-reader
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* @subpackage ISO 14496
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* @copyright Copyright (c) 2008 The PHP Reader Project Workgroup
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* @license http://code.google.com/p/php-reader/wiki/License New BSD License
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* @version $Id$
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*/
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/**#@+ @ignore */
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require_once("ISO14496/Box.php");
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/**#@-*/
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/**
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* The <i>The Item Location Box</i> provides a directory of resources in this or
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* other files, by locating their containing file, their offset within that
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* file, and their length. Placing this in binary format enables common handling
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* of this data, even by systems which do not understand the particular metadata
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* system (handler) used. For example, a system might integrate all the
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* externally referenced metadata resources into one file, re-adjusting file
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* offsets and file references accordingly.
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*
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* Items may be stored fragmented into extents, e.g. to enable interleaving. An
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* extent is a contiguous subset of the bytes of the resource; the resource is
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* formed by concatenating the extents. If only one extent is used then either
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* or both of the offset and length may be implied:
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*
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* o If the offset is not identified (the field has a length of zero), then
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* the beginning of the file (offset 0) is implied.
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* o If the length is not specified, or specified as zero, then the entire
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* file length is implied. References into the same file as this metadata,
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* or items divided into more than one extent, should have an explicit
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* offset and length, or use a MIME type requiring a different
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* interpretation of the file, to avoid infinite recursion.
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*
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* The size of the item is the sum of the extentLengths. Note: extents may be
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* interleaved with the chunks defined by the sample tables of tracks.
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*
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* The dataReferenceIndex may take the value 0, indicating a reference into the
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* same file as this metadata, or an index into the dataReference table.
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*
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* Some referenced data may itself use offset/length techniques to address
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* resources within it (e.g. an MP4 file might be included in this way).
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* Normally such offsets are relative to the beginning of the containing file.
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* The field base offset provides an additional offset for offset calculations
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* within that contained data. For example, if an MP4 file is included within a
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* file formatted to this specification, then normally data-offsets within that
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* MP4 section are relative to the beginning of file; baseOffset adds to those
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* offsets.
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*
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* @package php-reader
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* @subpackage ISO 14496
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* @author Sven Vollbehr <svollbehr@gmail.com>
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* @copyright Copyright (c) 2008 The PHP Reader Project Workgroup
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* @license http://code.google.com/p/php-reader/wiki/License New BSD License
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* @version $Rev$
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*/
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final class ISO14496_Box_ILOC extends ISO14496_Box
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{
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/** @var Array */
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private $_items = array();
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/**
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* Constructs the class with given parameters and reads box related data from
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* the ISO Base Media file.
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*
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* @param Reader $reader The reader object.
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*/
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public function __construct($reader)
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{
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parent::__construct($reader);
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$offsetSize = (($tmp = $this->_reader->readUInt32BE()) >> 28) & 0xf;
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$lengthSize = ($tmp >> 24) & 0xf;
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$baseOffsetSize = ($tmp >> 20) & 0xf;
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$itemCount = $this->_reader->readUInt16BE();
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for ($i = 0; $i < $itemCount; $i++) {
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$item = array();
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$item["itemId"] = $this->_reader->readUInt16BE();
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$item["dataReferenceIndex"] = $this->_reader->readUInt16BE();
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$item["baseOffset"] =
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($baseOffsetSize == 4 ? $this->_reader->readUInt32BE() :
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($baseOffsetSize == 8 ? $this->_reader->readInt64BE() : 0));
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$item["extents"] = array();
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for ($j = 0; $j < $extentCount; $j++) {
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$extent = array();
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$extent["offset"] =
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($offsetSize == 4 ? $this->_reader->readUInt32BE() :
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($offsetSize == 8 ? $this->_reader->readInt64BE() : 0));
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$extent["length"] =
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($lengthSize == 4 ? $this->_reader->readUInt32BE() :
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($lengthSize == 8 ? $this->_reader->readInt64BE() : 0));
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$item["extents"][] = $extent;
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}
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$this->_items[] = $item;
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}
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}
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/**
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* Returns the array of items. Each entry has the following keys set: itemId,
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* dataReferenceIndex, baseOffset, and extents.
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*
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* @return Array
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*/
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public function getItems() { return $this->_items; }
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}
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