Packet jitter mitigation for bursty transmission systems

• US 20080279226A1
• Filed: 05/08/2007
• Published: 11/13/2008
• Est. Priority Date: 05/08/2007
• Status: Active Grant

• Current Assignee: Zenith Electronics LLC (LG Corporation)
• Original Assignee: Zenith Electronics LLC (LG Corporation)
• Inventors: Laud, Timothy G.
• Granted Patent: US 7,733,921 B2
• Time in Patent Office: Days
• US Class Current: 370/535
• CPC Class Codes: H04N 21/23608 Remultiplexing multiplex streams, e.g. involving modifying time stamps or remapping the packet identifiers
• 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 21/2389 Multiplex stream processing, e.g. multiplex stream encrypting

Abstract

Audio packets occupy spaces in a packet stream so as to reduce packet jitter in a receiver.

Claims

1. A method of transmitting a digital signal comprising:

packing main stream audio data from an input data stream into an output data stream according to a first priority;

ignoring delayed null data in the input data stream;

packing main stream non-audio data from the input data stream into the output data stream according to a second priority, wherein the second priority is lower than the first priority;

packing enhanced data into the output data stream, wherein the enhanced data comprises data that is more robustly coded than the main stream audio data and the main stream non-audio data; and

,

transmitting the output data stream containing the packed main stream audio data, the packed main stream non-audio data, and the packed enhanced data.

2. The method of claim 1 further comprising:

receiving an input transport stream containing data-to-be-enhanced, the main stream audio data, the main stream non-audio data, and null data;

de-multiplexing the input transport stream into first and second outputs, wherein the first output contains the data-to-be-enhanced but not the main stream audio data, the main stream non-audio data, and the null data, and wherein the second output contains the main stream audio data, the main stream non-audio data, and the null data but not the data-to-be-enhanced; and

,

supplying the second output as the input data stream.

3. The method of claim 2 wherein the supplying of the second output as the input data stream comprises adding null data to replace the data-to-be-enhanced.

4. The method of claim 2 further comprising coding the data-to-be-enhanced in the first output as the enhanced data such that the enhanced data is more robust than the data-to-be-enhanced.

5. The method of claim 4 wherein the supplying of the second output as the input data stream comprises adding null data to replace the data-to-be-enhanced.

6. The method of claim 1 further comprising packing non-delayed null data into the output data stream prior to transmitting the output data stream.

7. The method of claim 6 further comprising:

receiving an input transport stream containing data-to-be-enhanced, the main stream audio data, the main stream non-audio data, and null data;

de-multiplexing the input transport stream into first and second outputs, wherein the first output contains the data-to-be-enhanced but not the main stream audio data, the main stream non-audio data, and the null data, and wherein the second output contains the main stream audio data, the main stream non-audio data, and the null data but not the data-to-be-enhanced; and

,

supplying the second output as the input data stream.

8. The method of claim 7 wherein the supplying of the second output as the input data stream comprises adding null data to replace the data-to-be-enhanced.

9. The method of claim 7 further comprising coding the data-to-be-enhanced in the first output as the enhanced data such that the enhanced data is more robust than the data-to-be-enhanced.

10. The method of claim 9 wherein the supplying of the second output as the input data stream comprises adding null data to replace the data-to-be-enhanced.

11. The method of claim 1 wherein the digital signal comprises a VSB digital television signal, wherein the main stream audio data comprises VSB audio data, and wherein the main stream non-audio data comprises VSB non-audio data.

12. A method of packing digital data from an input packet stream to an output packet stream, wherein the output packet stream includes reserved packing spaces and unreserved packing spaces, wherein the input packet stream has an other pointer and an audio pointer associated therewith, and wherein the output packet stream has a fill pointer associated therewith, the method comprising:

a) if the fill pointer points to one of the reserved packing spaces, packing no main stream audio packets, no main stream non-audio packets, and no null packets from the input packet stream to the space of the output packet stream to which the fill pointer points;

b) if the fill pointer points to one of the unreserved packing spaces, and if the audio pointer is less than or equal to the fill pointer, (i) packing a main stream audio packet from a space in the input packet stream to which the audio pointer points to a space in the output packet stream to which the fill pointer points, (ii) incrementing the audio pointer to a next space in the input packet stream containing an audio packet, and (iii) incrementing the fill pointer to a next space in the output packet stream;

c) if the fill pointer points to one of the unreserved packing spaces, if the audio pointer is not less than or equal to the fill pointer, and if the other pointer is less than or equal to the fill pointer, packing a main stream non-audio, non-null packet from a space in the input packet stream to which the other pointer points to a space in the output packet stream to which the fill pointer points, (ii) incrementing the other pointer to a next space in the input packet stream containing a non-audio, non-null packet, and (iii) incrementing the fill pointer to a next space in the output packet stream; and

,

d) if the fill pointer points to one of the unreserved packing spaces, if the audio pointer is not less than or equal to the fill pointer, and if the other pointer is not less than or equal to the fill pointer, (i) packing a remaining packet from the input packet stream to a space in the output packet stream to which the fill pointer points, and (ii) incrementing the fill pointer to a next space in the output packet stream.

13. The method of claim 12 wherein the reserved packing spaces are contiguous at a beginning of the output packet stream.

14. The method of claim 12 further comprising packing enhanced data packets into the reserved packing spaces.

15. The method of claim 12 further comprising transmitting the output packet stream.

16. The method of claim 12 wherein the digital data comprises VSB digital television data, wherein the main stream audio packets comprise VSB audio packets, wherein the main stream non-audio packets comprise VSB non-audio packets, and wherein the main stream non-audio, non-null packet comprises a VSB non-audio, non-null packet.

17. A method of packing digital data from an input packet stream to an output packet stream, wherein the output packet stream includes reserved packing spaces and unreserved packing spaces, wherein the input packet stream has an other pointer and an audio pointer associated therewith, and wherein the output packet stream has a fill pointer associated therewith, the method comprising:

a) if the fill pointer points to one of the reserved packing spaces, packing no main stream audio packets, no main stream non-audio packets, and no null packets from the input packet stream to the space of the output packet stream to which the fill pointer points;

b) if the fill pointer points to one of the unreserved packing spaces, if the audio pointer is less than or equal to the fill pointer, and if an audio buffer counter has a count less than x, (i) packing a main stream audio packet from a space in the input packet stream to which the audio pointer points to a space in the output packet stream to which the fill pointer points, (ii) incrementing the audio pointer to a next space in the input packet stream containing an audio packet, (iii) incrementing the fill pointer to a next space in the output packet stream, and (iv) adding y to the count of the audio buffer counter, wherein x and y are numbers;

c) decrementing the count of the audio buffer counter by one for each increment of the fill pointer;

d) if the fill pointer points to one of the unreserved packing spaces, if the audio pointer is not less than or equal to the fill pointer, and if the other pointer is less than or equal to the fill pointer, packing a main stream non-audio, non-null packet from a space in the input packet stream to which the other pointer points to a space in the output packet stream to which the fill pointer points, (ii) incrementing the other pointer to a next space in the input packet stream containing a non-audio, non-null packet, and (iii) incrementing the fill pointer to a next space in the output packet stream; and

,

e) if the fill pointer points to one of the unreserved packing spaces, if the audio pointer is not less than or equal to the fill pointer, and if the other pointer is not less than or equal to the fill pointer, (i) packing a remaining packet from the input packet stream to a space in the output packet stream to which the fill pointer points, and (ii) incrementing the fill pointer to a next space in the output packet stream.

18. The method of claim 17 wherein the reserved packing spaces are contiguous at a beginning of the output packet stream.

19. The method of claim 17 further comprising packing enhanced data packets into the reserved packing spaces.

20. The method of claim 17 further comprising transmitting the output packet stream.

21. The method of claim 17 wherein the digital data comprises VSB digital television data, wherein the main stream audio packets comprise VSB audio packets, wherein the main stream non-audio packets comprises VSB non-audio packets, and wherein the main stream non-audio, non-null packet comprises a VSB non-audio, non-null packet.