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. * * @package php-reader * @subpackage ID3 * @author Sven Vollbehr * @author Ryan Butterfield * @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(); } }