Add support for ID3v2.4
git-svn-id: http://php-reader.googlecode.com/svn/trunk@11 51a70ab9-7547-0410-9469-37e369ee0574
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svollbehr
190
src/ID3/ExtendedHeader.php
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190
src/ID3/ExtendedHeader.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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* 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 BEHR Software Systems 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 ID3
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* @copyright Copyright (c) 2008 BEHR Software Systems
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* @license http://www.opensource.org/licenses/bsd-license.php New BSD License
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* @version $Id$
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*/
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/**#@+ @ignore */
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require_once("Object.php");
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/**#@-*/
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/**
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* The extended header contains information that can provide further insight in
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* the structure of the tag, but is not vital to the correct parsing of the tag
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* information; hence the extended header is optional.
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*
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* @package php-reader
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* @subpackage ID3
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* @author Sven Vollbehr <sven.vollbehr@behrss.eu>
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* @copyright Copyright (c) 2008 BEHR Software Systems
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* @license http://www.opensource.org/licenses/bsd-license.php New BSD License
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* @version $Rev$
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*/
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final class ID3_ExtendedHeader extends ID3_Object
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{
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/**
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* A flag to denote that the present tag is an update of a tag found earlier
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* in the present file or stream. If frames defined as unique are found in
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* the present tag, they are to override any corresponding ones found in the
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* earlier tag. This flag has no corresponding data.
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*/
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const UPDATE = 128;
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/**
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* A flag to denote that a CRC-32 data is included in the extended header.
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* The CRC is calculated on all the data between the header and footer as
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* indicated by the header's tag length field, minus the extended header. Note
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* that this includes the padding (if there is any), but excludes the footer.
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* The CRC-32 is stored as an 35 bit synchsafe integer, leaving the upper four
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* bits always zeroed.
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*/
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const CRC32 = 64;
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/** A flag to denote whether or not the tag has restrictions applied on it. */
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const RESTRICTED = 32;
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/** @var integer */
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private $_size;
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/** @var integer */
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private $_flags;
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/** @var integer */
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private $_crc;
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/** @var integer */
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private $_restrictions;
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/**
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* Constructs the class with given parameters and reads object related data
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* from the ID3v2 tag.
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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($reader);
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$offset = $this->_reader->getOffset();
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$this->_size = $this->decodeSynchsafe32($this->_reader->getUInt32BE());
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$this->_reader->skip(1);
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$this->_flags = $this->_reader->getInt8();
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if ($this->hasFlag(self::UPDATE))
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$this->_reader->skip(1);
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if ($this->hasFlag(self::CRC32)) {
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$this->_reader->skip(1);
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$this->_crc = Transform::getInt32BE
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(($this->_reader->read(1) << 4) &
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$this->decodeSynchsafe32($this->_reader->read(4)));
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}
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if ($this->hasFlag(self::RESTRICTED)) {
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$this->_reader->skip(1);
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$this->_restrictions = $this->_reader->getInt8(1);
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}
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$this->_reader->skip($this->_size - $this->_reader->getOffset() - $offset);
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}
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/**
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* Returns the extended header size in bytes.
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*
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* @return integer
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*/
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public function getSize() { return $this->_size; }
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/**
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* Checks whether or not the flag is set. Returns <var>true</var> if the flag
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* is set, <var>false</var> otherwise.
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*
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* @param integer $flag The flag to query.
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* @return boolean
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*/
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public function hasFlag($flag) { return ($this->_flags & $flag) == $flag; }
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/**
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* Returns the CRC-32 data.
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*
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* @return integer
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*/
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public function getCRC() { return $this->_crc; }
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/**
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* Returns the restrictions. For some applications it might be desired to
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* restrict a tag in more ways than imposed by the ID3v2 specification. Note
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* that the presence of these restrictions does not affect how the tag is
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* decoded, merely how it was restricted before encoding. If this flag is set
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* the tag is restricted as follows:
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*
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* <pre>
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* Restrictions %ppqrrstt
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*
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* p - Tag size restrictions
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*
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* 00 No more than 128 frames and 1 MB total tag size.
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* 01 No more than 64 frames and 128 KB total tag size.
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* 10 No more than 32 frames and 40 KB total tag size.
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* 11 No more than 32 frames and 4 KB total tag size.
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*
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* q - Text encoding restrictions
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*
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* 0 No restrictions
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* 1 Strings are only encoded with ISO-8859-1 or UTF-8.
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*
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* r - Text fields size restrictions
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*
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* 00 No restrictions
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* 01 No string is longer than 1024 characters.
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* 10 No string is longer than 128 characters.
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* 11 No string is longer than 30 characters.
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*
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* Note that nothing is said about how many bytes is used to represent those
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* characters, since it is encoding dependent. If a text frame consists of
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* more than one string, the sum of the strungs is restricted as stated.
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*
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* s - Image encoding restrictions
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*
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* 0 No restrictions
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* 1 Images are encoded only with PNG [PNG] or JPEG [JFIF].
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*
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* t - Image size restrictions
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*
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* 00 No restrictions
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* 01 All images are 256x256 pixels or smaller.
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* 10 All images are 64x64 pixels or smaller.
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* 11 All images are exactly 64x64 pixels, unless required otherwise.
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* </pre>
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*
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* @return integer
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*/
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public function getRestrictions() { return $this->_restrictions; }
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}
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