Decoding Time to Sample Box contains a compact version of a table * that allows indexing from decoding time to sample number. Other tables give * sample sizes and pointers, from the sample number. Each entry in the table * gives the number of consecutive samples with the same time delta, and the * delta of those samples. By adding the deltas a complete time-to-sample map * may be built. * * The Decoding Time to Sample Box contains decode time delta's: DT(n+1) = DT(n) * + STTS(n) where STTS(n) is the (uncompressed) table entry for sample n. * * The sample entries are ordered by decoding time stamps; therefore the deltas * are all non-negative. * * The DT axis has a zero origin; DT(i) = SUM(for j=0 to i-1 of delta(j)), and * the sum of all deltas gives the length of the media in the track (not mapped * to the overall timescale, and not considering any edit list). * * The {@link ISO14496_Box_ELST Edit List Box} provides the initial CT value if * it is non-empty (non-zero). * * @package php-reader * @subpackage ISO 14496 * @author Sven Vollbehr * @copyright Copyright (c) 2008 The PHP Reader Project Workgroup * @license http://code.google.com/p/php-reader/wiki/License New BSD License * @version $Rev: 92 $ */ final class ISO14496_Box_STTS extends ISO14496_Box_Full { /** @var Array */ private $_timeToSampleTable = array(); /** * Constructs the class with given parameters and reads box related data from * the ISO Base Media file. * * @param Reader $reader The reader object. */ public function __construct($reader, &$options = array()) { parent::__construct($reader, $options); $entryCount = $this->_reader->readUInt32BE(); $data = $this->_reader->read ($this->getOffset() + $this->getSize() - $this->_reader->getOffset()); for ($i = 1; $i <= $entryCount; $i++) $this->_timeToSampleTable[$i] = array ("sampleCount" => Transform::fromUInt32BE(substr($data, ($i - 1) * 8, 4)), "sampleDelta" => Transform::fromUInt32BE(substr($data, $i * 8 - 4, 4))); } /** * Returns an array of values. Each entry is an array containing the following * keys. * o sampleCount -- an integer that counts the number of consecutive samples * that have the given duration. * o sampleDelta -- an integer that gives the delta of these samples in the * time-scale of the media. * * @return Array */ public function getTimeToSampleTable() { return $this->_timeToSampleTable; } }