org.dvb.dsmcc

Class DSMCCStream

java.lang.Object

org.dvb.dsmcc.DSMCCStream

Direct Known Subclasses:

DSMCCStreamEvent

public class DSMCCStream
extends Object

The DSMCCStream class is used to manage DSMCC Stream Objects. The BIOP::Stream message shall be read from the network once only, before the constructor of this class returns. Hence methods which return information from that message shall not be affected by any subsequent changes to that information.

The methods in this class relating to the NPT mechanism shall also be mapped onto the DVB timeline as defined in the main part of this specification. NOTE: The NPT mechanism and scheduled stream events that depend on it are known to be vulnerable to disruption in many digital TV distribution networks. Existing deployed network equipment that re-generates the STC is unlikely to be aware of NPT and hence will not make the necessary corresponding modification to STC values inside NPT reference descriptors. Applications should only use NPT where they are confident that the network where they are to be used does not have this problem.

See Also:

DSMCCObject

Constructor Summary

Constructors

Constructor and Description
DSMCCStream(DSMCCObject aDSMCCObject) Creates a Stream Object from a DSMCC Object.
DSMCCStream(String path) Create a Stream Object from its pathname.
DSMCCStream(String path, String name) Create a DSMCCStream from its pathname.

Method Summary

Methods

Modifier and Type	Method and Description
void	addNPTListener(NPTListener l) Add a listener for timeline events on the DSMCCStream object.
long	getDuration() This function returns the duration in milliseconds of the DSMCC Stream.
Time	getMediaTimeFromStream(long time, Clock c) Convert a time measured according to a timeline in the stream into a JMF media time measured in a specified clock.
long	getNPT() This function is used to get value of the current timeline in milliseconds.
NPTRate	getNPTRate() Get the rate for the timeline referenced in the DSMCCStream object.
Locator	getStreamLocator() This function returned a Locator referencing the streams of this collection.
boolean	isAudio() This function returns a boolean indicating if the Stream Object refers to an audio stream.
boolean	isData() This function returns a boolean indicating if the Stream Object refers to a data stream.
boolean	isMPEGProgram() This method will return true if the Stream(Event) BIOP message contains a tap with use field BIOP_PROGRAM_USE, otherwise it will return false.
boolean	isVideo() This function returns a boolean indicating if the Stream Object refers to an video stream.
void	removeNPTListener(NPTListener l) Remove a listener for timeline events on the DSMCCStream object.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DSMCCStream

public DSMCCStream(DSMCCObject aDSMCCObject)
            throws NotLoadedException,
                   IllegalObjectTypeException

Creates a Stream Object from a DSMCC Object. The BIOP message referenced by the DSMCCObject has to be a Stream or StreamEvent BIOP message.

Parameters:

aDSMCCObject - the DSMCC object which describes the stream

Throws:

NotLoadedException - the DSMCCObject is not loaded.

IllegalObjectTypeException - the DSMCCObject is neither a DSMCC Stream nor a DSMCCStreamEvent

DSMCCStream

public DSMCCStream(String path)
            throws IOException,
                   IllegalObjectTypeException

Create a Stream Object from its pathname. For an object Carousel, this method will block until the module which contains the object is loaded. The BIOP message referenced by the DSMCCObject pointed to by the parameter path has to be a Stream or StreamEvent BIOP message.

Parameters:

path - the pathname of the DSMCCStream Object.

Throws:

IOException - If an IO error occurred.

IllegalObjectTypeException - the DSMCCObject is neither a DSMCC Stream nor a DSMCCStreamEvent

DSMCCStream

public DSMCCStream(String path,
           String name)
            throws IOException,
                   IllegalObjectTypeException

Create a DSMCCStream from its pathname. For an object Carousel, this method will block until the module which contains the object is loaded. The BIOP message referenced by the DSMCCObject pointed to be the parameters path and name has to be a Stream or StreamEvent BIOP message.

Parameters:

path - the directory path.

name - the name of the DSMCCStream Object.

Throws:

IOException - If an IO error occurred.

IllegalObjectTypeException - the DSMCCObject is neither a DSMCC Stream nor a DSMCCStreamEvent

Method Detail

getDuration

public long getDuration()

This function returns the duration in milliseconds of the DSMCC Stream. If the DSMCCStream BIOP message does not specify duration, zero will be returned.

Returns:

The duration in milliseconds of the DSMCC Stream.

getNPT

public long getNPT()
            throws MPEGDeliveryException

This function is used to get value of the current timeline in milliseconds. Implementations are not required to continuously monitor for the timeline descriptors. In implementations which do not continuously monitor, this method will block while the current timeline is retrieved from the stream.

Returns:

the current time in milliseconds or zero if the DSMCC Stream object BIOP message does not contain any taps pointing to a timeline.

Throws:

MPEGDeliveryException - if there is an error in retrieving the timeline descriptors

getStreamLocator

public Locator getStreamLocator()

This function returned a Locator referencing the streams of this collection. The interpretation of the return value is determined by the isMPEGProgram method.

Returns:

a locator.

isMPEGProgram

public boolean isMPEGProgram()

This method will return true if the Stream(Event) BIOP message contains a tap with use field BIOP_PROGRAM_USE, otherwise it will return false.

Returns:

true only if the Stream(Event) BIOP message is as described above

isAudio

public boolean isAudio()

This function returns a boolean indicating if the Stream Object refers to an audio stream. This is the case if the audio field in the Stream(Event) BIOP message has a value different from zero.

Returns:

true only if the Stream object refers to an audio stream

isVideo

public boolean isVideo()

This function returns a boolean indicating if the Stream Object refers to an video stream. This is the case if the `video' field in the Stream(Event) BIOP message has a value different from zero otherwise false is returned.

Returns:

true only if the Stream object refers to an video stream

isData

public boolean isData()

This function returns a boolean indicating if the Stream Object refers to a data stream. This is the case if the data field in the Stream(Event) BIOP message has a value different from zero.

Returns:

true only if the Stream object refers to a data stream

getNPTRate

public NPTRate getNPTRate()
                   throws MPEGDeliveryException

Get the rate for the timeline referenced in the DSMCCStream object. Where the timeline is NPT, the NPT rate is returned. Where the timeline is the DVB timeline, 0/1 is returned if it is paused and 1/1 is returned if it is advancing. The method returns null if no timeline is referenced by the DSMCCStream object, (i.e. for NPT, no STR_NPT_USE tap in the list of taps).

Returns:

the NPT rate or null

Throws:

throws - MPEGDeliveryException if there is an error in retrieving NPT reference descriptors

MPEGDeliveryException

Since:

MHP 1.0.1

addNPTListener

public void addNPTListener(NPTListener l)

Add a listener for timeline events on the DSMCCStream object. Adding the same listener a second time has no effect.

Parameters:

l - the listener

Since:

MHP 1.0.1

removeNPTListener

public void removeNPTListener(NPTListener l)

Remove a listener for timeline events on the DSMCCStream object. Removing a non-subscribed listener has no effect.

Parameters:

l - the listener to remove

Since:

MHP 1.0.1

getMediaTimeFromStream

public Time getMediaTimeFromStream(long time,
                          Clock c)

Convert a time measured according to a timeline in the stream into a JMF media time measured in a specified clock.

Parameters:

time - the time measured according to the timeline in the stream

c - the clock to express the media time

Returns:

the JMF media time corresponding to the specified time

Throws:

IllegalArgumentException - if the Clock is not a Player which is presenting at least one of the streams of this collection (as returned by getStreamLocator).