Synchronised tempo codes 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. * * @category Zend * @package Zend_Media * @subpackage ID3 * @author Sven Vollbehr * @author Ryan Butterfield * @copyright Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com) * @license http://framework.zend.com/license/new-bsd New BSD License * @version $Id$ */ final class Zend_Media_Id3_Frame_Sytc extends Zend_Media_Id3_Frame implements Zend_Media_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 = Zend_Media_Id3_Timing::MPEG_FRAMES; /** @var Array */ private $_events = array(); /** * Constructs the class with given parameters and parses object related * data. * * @param Zend_Io_Reader $reader The reader object. * @param Array $options The options array. */ public function __construct($reader = null, &$options = array()) { parent::__construct($reader, $options); if ($this->_reader === null) { return; } $offset = 0; $this->_format = $this->_reader->readUInt8(); while ($this->_reader->available()) { $tempo = $this->_reader->readUInt8(); if ($tempo == 0xff) $tempo += $this->_reader->readUInt8(); $this->_events[$this->_reader->readUInt32BE()] = $tempo; } ksort($this->_events); } /** * Returns the timing format. * * @return integer */ public function getFormat() { return $this->_format; } /** * Sets the timing format. * * @see Zend_Media_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); } /** * Writes the frame raw data without the header. * * @param Zend_Io_Writer $writer The writer object. * @return void */ protected function _writeData($writer) { $writer->writeUInt8($this->_format); foreach ($this->_events as $timestamp => $tempo) { if ($tempo >= 0xff) { $writer->writeUInt8(0xff) ->writeUInt8($tempo - 0xff); } else { $writer->writeUInt8($tempo); } $writer->writeUInt32BE($timestamp); } } }