Apparatus and method for segmentation and time synchronization of the transmission of a multiple program multimedia data stream

• US 5,652,749 A
• Filed: 07/25/1996
• Issued: 07/29/1997
• Est. Priority Date: 02/03/1995
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Plotz, Kevin G., Delp, Gary Scott, Leichty, Philip Lynn, Lynch, Jeffrey James, Davenport, David William
• Primary Examiner(s): BLUM, RUSSELL
• Application Number:
  US08/687,268
• Time in Patent Office: 369 Days
• Field of Search: 379/93, 379/94, 379/96, 348/13, 348/17, 348/461, 348/464, 348/467, 348/473, 348/500, 348/512, 348/518, 370/466, 370/474, 370/476, 370/509
• US Class Current: 370/466
• CPC Class Codes: H04L 2012/5616 Terminal equipment, e.g. codecs, synch.
• CPC Class Codes: H04L 2012/5652 Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly
• CPC Class Codes: H04L 2012/5664 Support of Video, e.g. MPEG
• CPC Class Codes: H04N 21/2381 Adapting the multiplex stream to a specific network, e.g. an Internet Protocol [IP] network transmission of MPEG streams over ATM H04L12/5601
• CPC Class Codes: H04N 21/242 Synchronization processes, e.g. processing of PCR [Program Clock References] arrangements for synchronising broadcast or distribution via plural systems in broadcast distribution systems H04H20/18
• CPC Class Codes: H04N 21/4305 Synchronising client clock from received content stream, e.g. locking decoder clock with encoder clock, extraction of the PCR packets arrangements for synchronising receiver with transmitter by comparing receiver clock with transmitter clock H04L7/0012; arrangements for synchronising receiver with transmitter wherein the receiver takes measures against momentary loss of synchronisation H04L7/0083
• CPC Class Codes: H04N 21/4381 Recovering the multiplex stream from a specific network, e.g. recovering MPEG packets from ATM cells transmission of MPEG streams over ATM H04L12/5601
• CPC Class Codes: H04N 21/47202 for requesting content on demand, e.g. video on demand
• CPC Class Codes: H04N 21/64307 ATM
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

Method and apparatus are provided for segmenting a multiple program multimedia digital data stream for transmission over a distribution communications network. Each program multimedia digital data stream includes sequential transport system (TS) packets with program clock references (PCRs) at a set time interval and a program identification (PID) associated with the PCRs. The multiple program multimedia digital data stream is received. The TS packets are decoded to identify the program clock references (PCRs). A selected number N of TS packets are identified. The multimedia digital data stream into frames responsive to both the identified number N of TS packets and the identified PCRs. A program identification (PID) associated with one of the PCRs is selected for timing the transmission of segmented multiple program multimedia digital data stream. A time interval following an identified PCR associated with the selected program identification PID is identified and compared with the set time interval between the program clock references (PCRs). Responsive to the identified time interval being greater than the set time interval, a new program identification (PID) is selected for timing the transmission of segmented multiple program multimedia digital data stream.

Claims

1. Apparatus for segmenting a multiple program multimedia digital data stream for transmission over a distribution communications network, each program multimedia digital data stream including sequential transport system (TS) packets with at least one program clock reference (PCR) included within a set time interval and a program identification (PID) associated with the PCRs comprising:

means for decoding said TS packets to identify the program clock references (PCRs);

means for identifying a selected number N of TS packets;

means for segmenting said multimedia digital data stream into frames responsive to both said identified number N of TS packets and said identified PCR;

means for selecting a program identification (PID) associated with one of the PCRs for timing the transmission of segmented multiple program multimedia digital data stream;

means for identifying a time interval following an identified PCR associated with said selected program identification PID; and

means for comparing said identified time interval with the set time interval between the program clock references (PCRs); and

means responsive to said identified time interval being greater than the set time interval for selecting a new program identification (PID) associated with one of the PCRs for timing the transmission of segmented multiple program multimedia digital data stream.

2. Apparatus for segmenting a multiple program multimedia digital data stream as recited in claim 1 wherein said means for segmenting said multimedia digital data stream into frames responsive to both said identified number N of TS packets and said identified PCR include means for transforming said multimedia digital data stream TS packets directly into fixed size Asynchronous Transfer Mode (ATM) cells;

said ATM cells being transmitted over the distribution communications network and being reassembled into said multimedia digital data stream frames by a decoder/receiver coupled to the network.

3. Apparatus for segmenting a multiple program multimedia digital data stream as recited in claim 2 wherein said means for identifying said time interval following said identified PCR associated with said selected program identification PID include counter means for identifying a number of said ATM cells transmitted following said identified PCR.

4. Apparatus for segmenting a multiple program multimedia digital data stream as recited in claim 1 wherein said means for identifying said time interval following said identified PCR associated with said selected program identification PID include means for comparing the result of a target transmission time minus a base rate counter value with the set time interval.

5. Apparatus for segmenting a multiple program multimedia digital data stream as recited in claim 1 further include means responsive to said means for selecting a new PID for updating an offset value, said offset value used for timing the transmission of a digital data stream containing PCRs.

6. A method for segmenting a multimedia data stream for transmission over a distribution communications network, said multimedia data stream including sequential transport system (TS) packets with at least one program clock reference (PCR) included within a set time interval, said method comprising the steps of:

decoding said TS packets to identify the program clock references (PCRs);

identifying a selected number N of TS packets; and

segmenting said multimedia digital data stream into frames responsive to both said identified selected number N of TS packets and said identified PCR;

selecting a program identification (PID) associated with one of the PCRs for timing the transmission of segmented multiple program multimedia digital data stream;

identifying a time interval following an identified PCR associated with said selected program identification PID;

comparing said identified time interval with the set time interval between the program clock references (PCRs); and

selecting a new program identification (PID) associated with one of the PCRs for timing the transmission of segmented multiple program multimedia digital data stream responsive to said identified time interval being greater than the set time interval.

7. A method for segmenting a multiple program multimedia digital data stream as recited in claim 6 wherein the steps of selecting said PID and selecting said new PID include the step of decoding said TS packets to identify the current PID associated with one of said identified PCRs.

8. A method for segmenting a multiple program multimedia digital data stream as recited in claim 6 wherein said step of segmenting said multimedia digital data stream includes the step of transforming said multimedia digital data stream TS packets directly into fixed size Asynchronous Transfer Mode (ATM) cells.

9. A method for segmenting a multiple program multimedia digital data stream as recited in claim 8 wherein said step of identifying said time interval includes the step of counting a number of said ATM cells transmitted following said identified PCR.

10. A method for segmenting a multiple program multimedia digital data stream as recited in claim 6 wherein said step of identifying said time interval includes the step of comparing the result of a target transmission time minus a base rate counter value with the set time interval.

11. A method for segmenting a multiple program multimedia digital data stream as recited in claim 8 further includes the step of updating an offset value responsive to selecting said new PID, said offset value used for timing the transmission of a digital data stream containing PCRs.

12. A system for communicating a stream of multiple program multimedia digital data comprising:

a distribution communications network;

multimedia server means for receiving and segmenting the multiple program multimedia digital data stream and transmitting said segmented multiple program multimedia digital data stream over said distribution communications network;

said multimedia server means including segmenting means for segmenting said stream into frames responsive to both an identified selected number N of TS packets and an identified PCR and means for selecting a program identification (PID) associated with one of the PCRs for timing the transmission of segmented multiple program multimedia digital data stream; and

receiver means coupled to said distribution communications network for receiving the multimedia digital data stream.