Exploitation of null packets in packetized digital television systems

• US 7,848,364 B2
• Filed: 04/21/2008
• Issued: 12/07/2010
• Est. Priority Date: 01/03/2002
• Status: Expired due to Fees

• Current Assignee: The DIRECTV Group, Inc. (AT&T, Inc.)
• Original Assignee: The DIRECTV Group, Inc. (AT&T, Inc.)
• Inventors: Stranger, Leon J., Plummer, Robert H., Newman, Richard K., Basse, Hanno, Michener, James A.
• Primary Examiner(s): Jung; Min
• Application Number:
  US12/106,477
• Publication Number:
  US 20080198876A1
• Time in Patent Office: 960 Days
• Field of Search: 370/528, 370/537, 370/538, 370/540
• US Class Current: 370/528
• CPC Class Codes: H04J 3/1682 Allocation of channels according to the instantaneous demands of the users, e.g. concentrated multiplexers, statistical multiplexers
• CPC Class Codes: H04N 21/23611 Insertion of stuffing data into a multiplex stream, e.g. to obtain a constant bitrate synchronisation arrangements in time-division multiplex systems using bit stuffing for systems with different or fluctuating information rates H04J3/073
• CPC Class Codes: H04N 21/23614 Multiplexing of additional data and video streams arrangements for simultaneous broadcast of plural pieces of information H04H20/28
• CPC Class Codes: H04N 21/2365 Multiplexing of several video streams
• CPC Class Codes: H04N 21/23655 Statistical multiplexing, e.g. by controlling the encoder to alter its bitrate to optimize the bandwidth utilization
• CPC Class Codes: H04N 21/4347 Demultiplexing of several video streams
• CPC Class Codes: H04N 21/4348 Demultiplexing of additional data and video streams

Abstract

A system and method for adding auxiliary data D_A to an output data stream from a statistical multiplexer is disclosed. An auxiliary multiplexer accepts a statistically multiplexed data stream, and substitutes auxiliary data packets for null data packets. The auxiliary multiplexer controls the number of null packets in the statistically multiplexed data stream by controlling the target bandwidth B_T of the statistical multiplexer, or by modifying the statistical multiplexer equation to make the auxiliary data stream a participant in the negotiation process of allocating throughput among the data sources.

Claims

1. A method of adding auxiliary data D_A to a data stream, comprising the steps of:

accepting a statistically multiplexed data stream having null data, wherein the data stream comprises a set of data packets all having a packet ID including a first data packet and a second data packet temporally adjacent the first data packet; and

substituting at least a portion of the auxiliary data D_A for the null data in the statistically multiplexed data stream comprising substituting at least a portion of the auxiliary data D_A for the data in the second data packet if the first data packet includes at least a number NB of consecutive zero data values and the second data packet includes all zero data values.

2. The method of claim 1, wherein the auxiliary data D_A is non-opportunistic data.

3. The method of claim 2, further comprising the step of:

buffering the auxiliary data D_A until there is sufficient null data to permit the substitution of the at least some of the auxiliary data D_A in the statistically multiplexed data stream.

4. The method of claim 1, wherein the amount of null data is controlled according to a relationship between an amount of the buffered auxiliary data D_A and a capacity of a buffer storing the buffered data.

5. The method of claim 1, wherein the null data comprises statistical multiplexer null data N_SM.

6. The method of claim 1, wherein the null data comprises encoder null data N_E.

7. The method of claim 6, wherein the statistically multiplexed data stream is statistically multiplexed according to a statistical multiplexer equation, and the step of controlling an amount of null data in the statistically multiplexed data according to a relationship between the amount of buffered auxiliary data D_A and a capacity of a buffer storing the buffered data comprises the step of altering the statistical multiplexer equation.

8. The method of claim 1, further comprising the step of:

examining the auxiliary data D_A for non-essential data; and

eliminating the non-essential data from the auxiliary data D_A before substituting the auxiliary data D_A for the null data in the statistically multiplexed data stream.

9. The method of claim 1, wherein the step of amount of null data in the statistically multiplexed data is controlled according to a parameter set describing the auxiliary data D_A, including:

a minimum throughput required to keep the data service active BW_MIN;

a maximum sustained throughput of the data service BW_MAX; and

a nominal or guaranteed rate over a time period BW_AVG.

10. A method of adding auxiliary data D_A to a statistically multiplexed data stream, comprising the steps of:

controlling an amount of the null data in the statistically multiplexed data stream to provide sufficient null data to permit the substitution of at least some of the auxiliary data D_A in the statistically multiplexed data stream for the null data; and

substituting at least a portion of the auxiliary data D_A for the null data in the statistically multiplexed data stream.

11. The method of claim 10, wherein the auxiliary data D_A is non-opportunistic data.

12. The method of claim 11, further comprising the step of:

buffering the auxiliary data D_A until there is sufficient null data to permit the substitution of the at least some of the auxiliary data D_A in the statistically multiplexed data stream.

13. The method of claim 12, wherein the amount of null data is controlled according to a relationship between an amount of the buffered auxiliary data D_A and a capacity of a buffer storing the buffered data.

14. The method of claim 13, wherein the statistically multiplexed data stream is statistically multiplexed according to a statistical multiplexer equation, and the step of controlling an amount of null data in the statistically multiplexed data according to a relationship between the amount of buffered auxiliary data D_A and a capacity of a buffer storing the buffered data comprises the step of altering the statistical multiplexer equation.

15. The method of claim 10, wherein the null data comprises statistical multiplexer null data N_SM.

16. The method of claim 10, wherein the statistically multiplexed data stream is statistically multiplexed to a throughput less than or equal to a target throughput value BW_T, and the step of controlling an amount of null data in the statistically multiplexed data comprises the step of altering the target throughput value BW_T.

17. The method of claim 10, wherein the null data comprises encoder null data N_E.

18. The method of claim 10, further comprising the step of:

examining the auxiliary data D_A for non-essential data; and

eliminating the non-essential data from the auxiliary data D_A before substituting the auxiliary data D_A for the null data in the statistically multiplexed data stream.

19. The method of claim 10, wherein the step of amount of null data in the statistically multiplexed data is controlled according to a parameter set describing the auxiliary data D_A, including:

a minimum throughput required to keep the data service active BW_MIN;

a maximum sustained throughput of the data service BW_MAX; and

a nominal or guaranteed rate over a time period BW_AVG.