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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 ID3
* @copyright Copyright (c) 2008 The PHP Reader Project Workgroup
* @license http://code.google.com/p/php-reader/wiki/License New BSD License
* @version $Id: SYTC.php 107 2008-08-03 19:09:16Z svollbehr $
*/
/**#@+ @ignore */
require_once("ID3/Frame.php");
require_once("ID3/Timing.php");
/**#@-*/
/**
* For a more accurate description of the tempo of a musical piece, the
* <i>Synchronised tempo codes</i> frame might be used.
*
* The tempo data consists of one or more tempo codes. Each tempo code consists
* of one tempo part and one time part. The tempo is in BPM described with one
* or two bytes. If the first byte has the value $FF, one more byte follows,
* which is added to the first giving a range from 2 - 510 BPM, since $00 and
* $01 is reserved. $00 is used to describe a beat-free time period, which is
* not the same as a music-free time period. $01 is used to indicate one single
* beat-stroke followed by a beat-free period.
*
* The tempo descriptor is followed by a time stamp. Every time the tempo in the
* music changes, a tempo descriptor may indicate this for the player. All tempo
* descriptors must be sorted in chronological order. The first beat-stroke in
* a time-period is at the same time as the beat description occurs. There may
* only be one SYTC frame in each tag.
*
* @package php-reader
* @subpackage ID3
* @author Sven Vollbehr <svollbehr@gmail.com>
* @author Ryan Butterfield <buttza@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: 107 $
*/
final class ID3_Frame_SYTC extends ID3_Frame
implements ID3_Timing
{
/** Describes a beat-free time period. */
const BEAT_FREE = 0x00;
/** Indicate one single beat-stroke followed by a beat-free period. */
const SINGLE_BEAT = 0x01;
/** @var integer */
private $_format = ID3_Timing::MPEG_FRAMES;
/** @var Array */
private $_events = array();
/**
* Constructs the class with given parameters and parses object related data.
*
* @param Reader $reader The reader object.
* @param Array $options The options array.
*/
public function __construct($reader = null, &$options = array())
{
parent::__construct($reader, $options);
if ($reader === null)
return;
$offset = 0;
$this->_format = Transform::fromUInt8($this->_data[$offset++]);
while ($offset < strlen($this->_data)) {
$tempo = Transform::fromUInt8($this->_data[$offset++]);
if ($tempo == 0xff)
$tempo += Transform::fromUInt8($this->_data[$offset++]);
$this->_events
[Transform::fromUInt32BE(substr($this->_data, $offset, 4))] = $tempo;
$offset += 4;
}
ksort($this->_events);
}
/**
* Returns the timing format.
*
* @return integer
*/
public function getFormat() { return $this->_format; }
/**
* Sets the timing format.
*
* @see ID3_Timing
* @param integer $format The timing format.
*/
public function setFormat($format) { $this->_format = $format; }
/**
* Returns the time-bpm tempo events.
*
* @return Array
*/
public function getEvents() { return $this->_events; }
/**
* Sets the time-bpm tempo events.
*
* @param Array $events The time-bpm tempo events.
*/
public function setEvents($events)
{
$this->_events = $events;
ksort($this->_events);
}
/**
* Returns the frame raw data.
*
* @return string
*/
public function __toString()
{
$data = Transform::toUInt8($this->_format);
foreach ($this->_events as $timestamp => $tempo) {
if ($tempo >= 0xff)
$data .= Transform::toUInt8(0xff) . Transform::toUInt8($tempo - 0xff);
else
$data .= Transform::toUInt8($tempo);
$data .= Transform::toUInt32BE($timestamp);
}
parent::setData($data);
return parent::__toString();
}
}
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