Index Object are in terms of presentation times. The
* corresponding Offset field values of the Index Entry byte
* offsets that, when combined with the Block Position value of the
* Index Block, indicate the starting location in bytes of an ASF Data
* Packet relative to the start of the first ASF Data Packet in the file.
*
* An offset value of 0xFFFFFFFF is used to indicate an invalid offset value.
* Invalid offsets signify that this particular index entry does not identify a
* valid indexible point. Invalid offsets may occur for the initial index
* entries of a digital media stream whose first ASF Data Packet has a non-zero
* send time. Invalid offsets may also occur in the case where a digital media
* stream has a large gap in the presentation time of successive objects.
*
* The Index Object is not recommended for use with files where the
* Send Time of the first Data Packet within the Data
* Object has a Send Time value significantly greater than zero
* (otherwise the index itself will be sparse and inefficient).
*
* Any ASF file containing an Index Object does also contain an Index
* Parameters Object in its {@link ASF_Object_Header ASF Header}.
*
* @package php-reader
* @subpackage ASF
* @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: 108 $
*/
final class ASF_Object_Index extends ASF_Object
{
/**
* Indicates that the index type is Nearest Past Data Packet. The Nearest
* Past Data Packet indexes point to the data packet whose presentation time
* is closest to the index entry time.
*/
const NEAREST_PAST_DATA_PACKET = 1;
/**
* Indicates that the index type is Nearest Past Media. The Nearest Past
* Object indexes point to the closest data packet containing an entire object
* or first fragment of an object.
*/
const NEAREST_PAST_MEDIA = 2;
/**
* Indicates that the index type is Nearest Past Cleanpoint. The Nearest Past
* Cleanpoint indexes point to the closest data packet containing an entire
* object (or first fragment of an object) that has the Cleanpoint Flag set.
*
* Nearest Past Cleanpoint is the most common type of index.
*/
const NEAREST_PAST_CLEANPOINT = 3;
/** @var integer */
private $_indexEntryTimeInterval;
/** @var Array */
private $_indexSpecifiers = array();
/** @var Array */
private $_indexBlocks = array();
/**
* Constructs the class with given parameters and reads object related data
* from the ASF file.
*
* @param Reader $reader The reader object.
* @param Array $options The options array.
*/
public function __construct($reader, &$options = array())
{
parent::__construct($reader, $options);
$this->_indexEntryTimeInterval = $this->_reader->readUInt32LE();
$indexSpecifiersCount = $this->_reader->readUInt16LE();
$indexBlocksCount = $this->_reader->readUInt32LE();
for ($i = 0; $i < $indexSpecifiersCount; $i++)
$this->_indexSpecifiers[] = array
("streamNumber" => $this->_reader->readUInt16LE(),
"indexType" => $this->_reader->readUInt16LE());
for ($i = 0; $i < $indexBlocksCount; $i++) {
$indexEntryCount = $this->_reader->readUInt32LE();
$blockPositions = array();
for ($i = 0; $i < $indexSpecifiersCount; $i++)
$blockPositions[] = $this->_reader->readInt64LE();
$offsets = array();
for ($i = 0; $i < $indexSpecifiersCount; $i++)
$offsets[] = $this->_reader->readUInt32LE();
$this->_indexBlocks[] = array
("blockPositions" => $blockPositions,
"indexEntryOffsets" => $offsets);
}
}
/**
* Returns the time interval between each index entry in ms.
*
* @return integer
*/
public function getIndexEntryTimeInterval()
{
return $this->_indexEntryTimeInterval;
}
/**
* Returns an array of index specifiers. Each entry consists of the following
* keys.
*
* o streamNumber -- Specifies the stream number that the Index
* Specifiers refer to. Valid values are between 1 and 127.
*
* o indexType -- Specifies the type of index.
*
* @return Array
*/
public function getIndexSpecifiers() { return $this->_indexSpecifiers; }
/**
* Returns an array of index entries. Each entry consists of the following
* keys.
*
* o blockPositions -- Specifies a list of byte offsets of the beginnings of
* the blocks relative to the beginning of the first Data Packet (for
* example, the beginning of the Data Object + 50 bytes).
*
* o indexEntryOffsets -- Specifies the offset. An offset value of
* 0xffffffff indicates an invalid offset value.
*
* @return Array
*/
public function getIndexBlocks() { return $this->_indexBlocks; }
}