Method and apparatus for detecting and controlling data stream splicing in ATM networks

• US 6,067,303 A
• Filed: 02/25/1997
• Issued: 05/23/2000
• Est. Priority Date: 02/25/1997
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Poulter, David Richard, Slane, Albert Alfonse, Aaker, Kenneth Dale, Delp, Gary Scott
• Primary Examiner(s): Kizou, Hassan
• Assistant Examiner(s): Pezzlo, John
• Application Number:
  US08/805,982
• Time in Patent Office: 1,183 Days
• Field of Search: 370/394, 370/395, 370/466, 370/473, 370/474, 370/522, 348/9, 348/464, 348/465, 348/7
• US Class Current: 370/474
• CPC Class Codes: H04L 12/5601 Transfer mode dependent, e.g. ATM
• CPC Class Codes: H04L 2012/561 Star, e.g. cross-connect, concentrator, subscriber group equipment, remote electronics
• CPC Class Codes: H04L 2012/5664 Support of Video, e.g. MPEG
• CPC Class Codes: H04L 2012/5672 Multiplexing, e.g. coding, scrambling

Abstract

A method and apparatus are provided for detecting and controlling data stream splicing in a stream of multimedia digital data over a distribution communications network. Sequential transport stream packets are obtained. Predetermined fields of each transport stream packet are interrogated to identify a splice in the data stream. A predetermined task is initiated responsive to an identified splice. In accordance with feature of the invention, one predetermined task initiated responsive to the identified splice includes masking the interrogated predetermined fields to mask the splice in the data stream.

Claims

1. A method for detecting and controlling data stream splicing across data communications networks comprising the steps of:

obtaining sequential transport stream packets;

interrogating predetermined fields of each transport stream packet to identify a splice in the data stream;

wherein the data stream is a MPEG-2 data stream and said interrogating step including the steps of interrogating a continuity counter and comparing a current continuity counter value with a last continuity counter value and identifying said splice in the data stream responsive to a predetermined difference between said current continuity counter value and said last continuity counter value; and

initiating a predetermined task responsive to an identified splice;

wherein the data stream is a MPEG-2 data stream and wherein said step of interrogating predetermined fields of each transport stream packet to identify a splice in the data stream includes the step of checking a splice countdown indicator for each transport stream packet;

further includes the steps of

saving an identified splice countdown value and a PID field for an identified transport stream packet containing said splice countdown indicator;

checking said PID field for a next transport stream packet, and responsive to an identified different PID, obtaining a next transport stream packet and checking said PID field for said next transport stream packet;

responsive to an identified matching PID, decrementing said splice countdown value and comparing a resulting splice countdown value with zero.

2. A method for detecting and controlling data stream splicing across data communications networks as recited in claim 1 further includes the step of identifying said splice in the data stream responsive to an identified matching zero splice countdown value.

3. A method for detecting and controlling data stream splicing across data communications networks as recited in claim 1 wherein said step of initiating said predetermined task responsive to said identified splice includes the step of buffering a spliced stream.

4. A method for detecting and controlling data stream splicing across data communications networks comprising the steps of:

obtaining sequential transport stream packets;

interrogating predetermined fields of each transport stream packet to identify a splice in the data stream;

initiating a predetermined task responsive to an identified splice;

said step of initiating said predetermined task responsive to said identified splice includes the step of masking said interrogated predetermined fields of an identified transport stream packet to mask said splice in the data stream;

wherein said masking step includes the steps of

identifying private data present;

clearing a splice point flag;

collapsing a splice countdown field;

incrementing a private data length value;

copying private data shifted by said collapsed splice countdown field; and

inserting fill bits to pad for said collapsed splice countdown field; and

responsive to identifying an absence of private data, clearing said splice point flag;

clearing a last splice countdown field and establishing a transport private data length set to zero.

5. A method for detecting and controlling data stream splicing across data communications networks comprising the steps of:

obtaining sequential transport stream packets;

interrogating predetermined fields of each transport stream packet to identify a splice in the data stream;

wherein the data stream is a MPEG-2 data stream and said interrogating step including the steps of interrogating a continuity counter and comparing a current continuity counter value with a last continuity counter value and identifying said splice in the data stream responsive to a predetermined difference between said current continuity counter value and said last continuity counter value; and

initiating a predetermined task responsive to an identified splice;

wherein said step of initiating said predetermined task responsive to said identified splice includes the steps of checking for a present adaptation block;

responsive to an identified present adaptation block checking for a present program clock reference (PCR);

responsive to an identified PCR checking for a present discontinuity indicator; and

responsive to an identified present discontinuity indicator, resetting said discontinuity indicator, calculating a updated correction value for said PCR and setting said PCR with said calculated updated correction value.

6. A method for detecting and controlling data stream splicing across data communications networks as recited in claim 5 further includes the steps responsive to an identified absence of a discontinuity indicator, setting said PCR with a current correction value.

7. A method for detecting and controlling data stream splicing across data communications networks comprising the steps of:

obtaining sequential transport stream packets;

interrogating predetermined fields of each transport stream packet to identify a splice in the data stream;

wherein the data stream is a MPEG-2 data stream and said interrogating step including the steps of interrogating a continuity counter and comparing a current continuity counter value with a last continuity counter value and identifying said splice in the data stream responsive to a predetermined difference between said current continuity counter value and said last continuity counter value; and

initiating a predetermined task responsive to an identified splice;

wherein said step of initiating said predetermined task responsive to said identified splice includes the step of deleting the spliced data stream.

8. A method for detecting and controlling data stream splicing across data communications networks as recited in claim 7 wherein said step of interrogating predetermined fields of each transport stream packet to identify a splice in the data stream includes the step of checking a splice countdown indicator for each transport stream packet.

9. A method for detecting and controlling data stream splicing across data communications networks as recited in claim 7 includes the steps of identifying user selections to control identifying said splice and identifying user selections to select said predetermined tasks.

10. A method for detecting and controlling data stream splicing across data communications networks comprising the steps of:

obtaining sequential transport stream packets;

interrogating predetermined fields of each transport stream packet to identify a splice in the data stream;

wherein the data stream is a MPEG-2 data stream and said interrogating step including the steps of interrogating a continuity counter and comparing a current continuity counter value with a last continuity counter value and identifying said splice in the data stream responsive to a predetermined difference between said current continuity counter value and said last continuity counter value; and

initiating a predetermined task responsive to an identified splice;

wherein said step of initiating said predetermined task responsive to said identified splice includes the step of substituting another data stream for the spliced data stream.

11. A method for detecting and controlling data stream splicing across data communications networks as recited in claim 10 wherein said predetermined difference is a value greater than two.

12. Apparatus for detecting and controlling data stream splicing across data communications networks comprising:

means for obtaining sequential transport stream packets from the data streams;

means for interrogating predetermined fields of each transport stream packet to identify a splice in the data stream;

means for initiating a predetermined task responsive to an identified splice;

means for receiving user selections to control said means for identifying said splice; and

means for receiving user selections to select said predetermined tasks;

wherein said means for initiating said predetermined task responsive to said identified splice include means for masking said interrogated predetermined fields of an identified transport stream packet to mask said splice in the data stream.