System and method for allocating packet identifiers in a transport stream in a subscriber network

• US 20020184649A1
• Filed: 06/04/2001
• Published: 12/05/2002
• Est. Priority Date: 06/04/2001
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Scientific-Atlanta LLC (Cisco Systems, Inc.)
• Inventors: Wilson, Thomas C.
• Granted Patent: US 7,496,092 B2
• Time in Patent Office: Days
• US Class Current: 725/114
• CPC Class Codes: H04N 21/235 Processing of additional data, e.g. scrambling of additional data or processing content descriptors
• CPC Class Codes: H04N 21/2362 Generation or processing of Service Information [SI]
• CPC Class Codes: H04N 21/4345 Extraction or processing of SI, e.g. extracting service information from an MPEG stream
• CPC Class Codes: H04N 21/435 Processing of additional data, e.g. decrypting of additional data, reconstructing software from modules extracted from the transport stream

Abstract

An apparatus in a digital network includes the logic for allocating and assigning packet identifiers (PIDs) to digital packets, such as MPEG packets. The logic can reside in a device that transmits a transport stream or a device that controls a transport stream transmitter. In the preferred embodiment, a session number is associated a program and with an output port of a transport stream transmitter; and the session number is unique for that output port. The logic associates a PID from a set of allocated PIDs with the session number. The set of allocated PID values are PMT_PIDs, which are used for identifying the PMT packets, and the set of PMT_PIDs is scalable. In the preferred embodiment, the logic also associates the PMT_PID to the session number using a predetermined scheme. The apparatus also includes logic for assigning a set of PID values to the elementary streams of a program. In the preferred embodiment, number of PIDs assigned to the elementary streams of a program is no more than the number of elementary streams of the program.

Claims

1. A method of allocating PID values to a program in a digital transport stream, the digital transport stream including at least one program including of a plurality of elementary streams, the method comprising the steps of:

(a) assigning a session number to a session, wherein the session is associated with a program having a plurality of elementary streams;

(b) associating a PMT_PID value with the session number;

(c) assigning a set of PID values to the elementary streams of the program; and

(d) indicating in a map of allocable PID values the assigned PID values.

2. The method of claim 1, further including the step of:

associating the session number with an output port, wherein the program that is associated with the session is transmitted from the output port.

3. The method of claim 1, prior to step (a), further including the step of:

determining from a map of session numbers an unassigned session number, wherein the unassigned session number is the session number assigned to the session in step (a).

4. The method of claim 3, wherein the map of session numbers is an array of elements, each element of the array is associated with a session number and has an unassigned state and an assigned state;

and further including the step of;

when the session number is assigned to the session, indicating the state of the element that is associated with the session number as assigned.

5. The method of claim 4, wherein the elements of the array are checked based upon their index values in the array, and the element having the lowest index value and an unassigned state is assigned to the session.

6. The method of claim 3, wherein the map of session numbers is a plurality of arrays, each array of the plurality of arrays is associated with an output port.

7. The method of claim 1, prior to the steps of (a), (b), (c) and (d), further including the step of:

receiving a session message having a program indicator included therein, wherein the in response to the session message steps (a), (b) and (c) are implemented to assign a first session number to a first session that is associated with a first program identified by the program identifier, associate a first PMT_PID value to the first session number and assign a first set of PID values to the elementary streams of the first program; and

after steps of (a), (b) and (c), further including the step of;

transmitting from a device the elementary streams of the program in a digital transport stream.

8. The method of claim 7, wherein the device that transmits the program has a plurality of output ports that are adapted to transmit digital transport streams, and the session message further includes an output port identifier that identifies the output port of the plurality of output ports from which the elementary streams of the first program are transmitted.

9. The method of claim 8, wherein the first session is associated with the output port identified by the output port identifier.

10. The method of claim 9, further including the steps of:

receiving a second session message having a second output port identifier and a second program indicator included therein, wherein the second program indicator identifies a second program, wherein the output port identifier identifies an output port, and wherein in response to the second message steps (a), (b) and (c) are implemented to assign a second session number to a second session that is associated with the second program, associate a second PMT_PID value to the second session number and assign a second set of PID values to the elementary streams of the second program; and

transmitting from the output port identified by the second session message the elementary streams of the second program.

11. The method of claim 10, wherein the output port associated with the first session is different from the second output port, the first and second session numbers are the same, and the first and second PMT_PID values are the same.

12. The method of claim 10, wherein the first program and the second program are the same program, and the first and second set of PID values assigned to the elementary streams of the program are the same.

13. The method of claim 10, wherein the output port associated with the first session is the same as the second output port, and the numerical values of the first and second PMT_PID values are related to the numerical values of the first and second session numbers.

14. The method of claim 1, further including the steps of:

allocating a first set of PID values for use as PMT_PIDs, wherein only PIDs from the first set of PID values are associated with PMT packets; and

allocating a second set of PID values for assignment to elementary streams of programs, wherein only PIDs from the second set of PID values are assigned to elementary streams of a program.

15. The method of claim 1, further including the steps of:

receiving a session message having a program identifier included therein;

determining the number of elementary streams of the identified program, wherein the number of PID values in the set of PID values assigned to the elementary streams of the program is less than or equal to the number of elementary streams of the identified program.

17. The apparatus of claim 16, wherein the value of the PMT_PID assigned to the session is related to the session number of the session.

18. The apparatus of claim 16, wherein the number of PIDs in the set of allocated PIDs is no more than the number of elementary streams of the program.

19. The apparatus of claim 16, wherein the set of allocated PIDs have values that are not contiguous.

20. The apparatus of claim 16, further including:

a plurality of output ports, each output port of the plurality of output ports adapted to transmit a transport stream having at least one program, wherein each program transmitted from an output port is associated with a unique session number.

21. The apparatus of claim 20, wherein a first output port of the plurality of output ports transmits a first transport stream, which includes a first program having a first program number associated therewith, a second output port of the plurality of output ports transmits a second transport stream, which includes a second program having a second program number, which is different than the first program number, associated therewith, the first and second programs each having a PMT identified by a PMT_PID value associated therewith, and the first and the second PMTs have the same PMT_PID value.

22. The apparatus of claim 21, wherein the first and second programs are the same particular program, and the elementary streams of the particular program have the same PID values in the first and second transport stream.

23. The apparatus of claim 20, wherein a first output port of the plurality of output ports transmits a first transport stream, which includes a first program having a program number associated therewith, a second output port of the plurality of output ports transmits a second transport stream, which includes a second program having the program number associated therewith, the first and second programs each having a PMT identified by a PMT_PID value associated therewith, and the first and the second PMTs have the different PMT_PID values.

24. The apparatus of claim 23, wherein the first and second programs are the same particular program, and the elementary streams of the particular program have the same PID values in the first and second transport stream.

25. The apparatus of claim 20, further including:

a first input port adapted to receive a session message having a program identifier and an output port identifier included therein, wherein the output port identifier identifies an output port of the plurality of output ports;

a second input port in communication with the plurality of output ports, the second input port adapted to receive a transport stream having a plurality of programs included therein, wherein the plurality of programs include a first program associated with the program identifier; and

wherein the means for assigning a session number uses the session message to assign a session number for a further session associated with the identified output port, thereby including the first program in the transport stream transmitted from the identified output port.

26. The apparatus of claim 16, wherein the means for assigning a session number includes a session number map.

27. The apparatus of claim 26, wherein the session number map is an array of elements having a first and second state, each element is associated with a session number, the first state representing an unassigned session number and the second state representing an assigned session number

28. The apparatus of claim 27, wherein the means for assigning a session number searches the array of elements for an element in the first state and assigns the session number associated with that element to the session, and changes the state of that element of the array to the second state.

29. The apparatus of claim 27, wherein each element of the array is associated with a PMT_PID.

30. The apparatus of claim 16, further including:

a plurality of output ports, each output port adapted to transmit a transport stream therefrom; and

wherein the means for assigning session numbers includes a session number map, the session number map including a plurality of arrays, each array associated with an output port of the plurality of output ports.

31. The apparatus of claim 30, wherein each array of the plurality of arrays include a plurality of elements, and each element is associated with a PMT_PID value.

32. The apparatus of claim 16, wherein the means for allocating a set of PID values includes a PID allocation map.

33. The apparatus of claim 32, wherein the PID allocation map includes an array of elements associated with PID numbers.

34. The apparatus of claim 32, further including:

a plurality of output port, each output port of the plurality of output ports is adapted to transmit a transport stream having at least one program included therein; and

wherein the PID allocation map includes a plurality of arrays, each array of the plurality of arrays including a plurality of elements and each array is associated with an output port, each element of the plurality of elements is associated with PID numbers.

36. The apparatus of claim 35, wherein the value of the PMT_PID assigned to the session is related to the session number of the session.

37. The apparatus of claim 35, further including:

an output port adapted to transmit a transport stream having at least one program, and wherein the logic for assigning a session number includes a map that associates the session number with the output port.

38. The apparatus of claim 35, wherein the logic for assigning a PMT_PID includes a map of PID values.

16. An apparatus in a digital network that includes a transport stream having a plurality of programs included therein, wherein a program is defined by a set of elementary streams, the apparatus comprising:

means for assigning a session number to a session, wherein a session is associated with a program of the transport stream;

means for assigning a PMT_PID to the session; and

means for allocating a set of PIDs to a set of elementary streams of a program.

35. An apparatus in a digital network that includes a transport stream having a plurality of programs included therein, wherein a program is defined by a set of elementary streams, the apparatus comprising:

logic adapted to assign a session number to a session, wherein a session is associated with a program of the transport stream;

logic adapted to assign a PMT_PID to the session; and

logic adapted to allocate a set of PIDs to a set of elementary streams of a program.