Method and system for reducing switching delays between digital video feeds using multicast slotted transmission technique

• US 20070250890A1
• Filed: 02/06/2007
• Published: 10/25/2007
• Est. Priority Date: 02/06/2006
• Status: Active Grant

• Current Assignee: Espial Incorporated (Enghouse Systems Limited)
• Original Assignee: Espial Incorporated (Enghouse Systems Limited)
• Inventors: Joshi, Vinay, Menon, Satish, Muthukumarasamy, Jayakumar, Malik, Rajiv
• Granted Patent: US 7,793,329 B2
• Time in Patent Office: Days
• US Class Current: 725/120
• CPC Class Codes: H04L 12/1877 Measures taken prior to transmission
• CPC Class Codes: H04N 21/26275 for distributing content or additional data in a staggered manner, e.g. repeating movies on different channels in a time-staggered manner in a near video on demand system
• CPC Class Codes: H04N 21/4384 involving operations to reduce the access time, e.g. fast-tuning for reducing channel switching latency
• CPC Class Codes: H04N 21/6125 involving transmission via Internet transmission by internet of broadcast information H04H60/82
• CPC Class Codes: H04N 21/6405 Multicasting data broadcast and multicast in packet switching networks H04L12/18
• CPC Class Codes: H04N 7/17318 Direct or substantially direct transmission and handling of requests

Abstract

Method and system for reducing switching delays between digital video feeds using multicast slotted transmission technique. Method, system, computer program stored on a computer readable medium for reducing switching delays between digital video feeds or different video or data channels using a slotted distribution and transmission technique. Method and system for performing a fast channel change operation. A computer propagated data signal. An article of manufacture comprising a digital video signal set.

Claims

1. A method for performing a fast channel change operation comprising:

receiving an input data stream;

performing a data stream channel switching operation from a first data stream to a second data stream;

generating a plurality of output data streams, each of the output data streams having a substantially identical data but having a timing of the data in each of the output data streams that have a time shift relative to each of the other output data streams; and

communicating the plurality of output data streams to a client device over a first communication link.

2. A method as in claim 1, wherein the input comprises a multicast data stream.

3. A method as in claim 1, wherein the input data stream is received from an external network.

4. A method as in claim 1, wherein a plurality of output multicast data streams are generated from a single multicast input, and each of the multicast output data streams having a substantially identical data but having a timing of the data in each of the output multicast data streams that have a time shift relative to each of the other output multicast data streams.

5. A method as in claim 4, wherein the time shift is a fixed predetermined time shift relative to each of the other output data streams.

6. A method as in claim 4, wherein the time shift is a variable dynamically determined time shift relative to each of the other output data streams.

7. A method as in claim 1, wherein the client comprises a media content rendering device.

8. A method as in claim 1, wherein the client comprises a subscriber home set-top-box.

9. A method as in claim 1, wherein the first communications link comprises a digital subscriber line (DSL) compatible communications link.

10. A method as in claim 1, wherein the digital subscriber line (DSL) compatible communications link couples the plurality of output signals to the client.

11. A method as in claim 1, wherein the data stream switching operation from a first data stream to a second data stream comprises a switching operation from a first channel data stream to a second channel data stream.

12. A method as in claim 1, wherein the signals are received by an appliance that performs a soft video switch-over between a multicast data stream of a first media content stream and one of a plurality of multicast data streams of a second media content stream, each of the plurality of multicast data streams having the same content but a different timing.

13. A method as in claim 12, wherein the appliance includes a DSLAM network device capability and communicates data signals from multiple customer Digital Subscriber Line (DSL) connections, and communicates data signals on a high-speed backbone line using signal multiplexing and/or demultiplexing techniques.

14. A method as in claim 13, wherein the signals communicated include sending data signals from the high-speed backbone to the multiple customer Digital Subscriber Line (DSL) connections.

15. A method as in claim 12, wherein the appliance is coupled for communication to an end subscriber client at a telephone company central office.

16. A method as in claim 1, wherein the time shift for each of the plurality of output signals is determined by a prescribed switching time requirement.

17. A method as in claim 1, wherein the data stream comprises a first image data type from which a complete representation of the image may be reconstructed and a second image data type from which the complete representation of the image may not alone be reconstructed and wherein the time shift for each of the plurality of output signals is determined as a fraction of the time period between successive portions of the data stream having the first image data type.

18. A method as in claim 17, wherein the data comprises data selected from the set of data consisting of:

digital image data, digital video data, digital video data including digital video data frames, and digital video data including digital video stand-alone frames or key frames.

19. A method as in claim 17, wherein the data comprises Random Access Points (RAPs) data frames.

20. A method as in claim 19, wherein the data comprises Random Access Points (RAPs) data frames separated by a predetermined temporal separation that is in integral fraction of the time between adjacent sequential random access points.

21. A method as in claim 19, wherein the data comprises Random Access Points (RAPs) data frames separated by a predetermined temporal separation that is in integral fraction of the time between adjacent sequential random access points, and the integral fractions are an integral fraction of 1/N, where N represents the plurality of multicasts for an input channel.

22. A method as in claim 1, wherein once the subscriber client selects a particular channel or particular video stream and the client devices selects and joins a particular one of the plurality of available data streams the client continues to receive and view the selected particular one of the plurality of available data streams until the subscriber client changes channel or stops viewing.

23. A method as in claim 22, wherein once the selected particular channel or particular video stream comprises a multicast video stream.

24. A method as in claim 1, wherein the data stream comprises a plurality of image frames includes at least one stand-alone image frame that has a first information content that permits it to be independently decoded and other image frames that have a second information content that does not permit them to be independently decoded.

25. A method as in claim 24, wherein the data stream comprises a plurality of video image frames including at least one stand-alone image RAP frame that has a first information content that permits it to be independently decoded, and other image frames selected from forward or bidirectional predicted video image frames that have a second information content that does not permit them to be independently decoded.

26. A method as in claim 24, wherein the appliance comprises a network server.

27. A method as in claim 24, wherein the appliance comprises a component within a network server.

28. A method as in claim 24, wherein the appliance comprises a component within a Digital Subscriber Line Access Multiplexer (DSLAM).

29. A method as in claim 24, wherein the appliance comprises a Digital Subscriber Line Access Multiplexer (DSLAM).

30. A method as in claim 24, wherein the stand-alone image frames are selected from the set of stand-alone image frames consisting of:

(i) Intra Coded frames or I-frames, (ii) Random Access Points or RAPs, (iii) any image frame that can be independently decoded to construct or reconstruct an original image without reference to another image frame, and (iv) any combination of two or more of these frames.

31. A method as in claim 30, wherein the other image frames are selected from the set of stand-alone image frames consisting of:

(i) a predicted image frame, (ii) a forward predicted image frame or P-frame, (iii) a bidirectional predicted image frame or B-frame, and (iv) any combination of two or more of these frames.

42. A computer program stored on a computer readable media including executable computer program instructions for executing in a processor logic for performing the method of claim 1.

50. A computer program product comprising a set of program instructions operable to permit a plurality of computers to carry out the method as claimed in claim 1.

32. A method of changing a data stream from a first data stream to a second data stream, the first data stream being received on a first channel and the second data stream being received on a second channel, the method comprising the steps on the receipt of each channel change request, of:

(1) determining the multicast it needs to join to experience the best latency for channel change, and generating a Join request which is sent to a channel server;

(2) for the new join request received from the Channel Server, querying a buffer list storing metadata related to the data stream;

(3) determining the nearest existing multicast group (referred as nMG) for the channel that satisfies or comes the closest to satisfying predetermined goals or conditions;

(4) receiving the identity of the nearest existing multicast group (nMG); and

(5) the client joining the nearest existing multicast group (nMG).

33. A method as in claim 32, wherein one of the server and the client determining the nearest existing multicast group.

34. A method as in claim 32, wherein the client determining the multicast it needs to join further comprising:

(1)(i) providing, by the server, a client with information that permits identification of one particular data stream having a certain program content and timing from a plurality of data streams having the same certain program content but different timings, the different timings representing time delays relative to other of the data streams;

(1)(ii) generating a client-side request to view a particular data stream;

(1)(iii) performing a calculation to identify the one particular data stream having a certain program content and timing from the plurality of data streams having the same certain program content but different timings; and

(1)(iv) generating a request to receive the identified one particular data stream and communicating the request to the source of the identified one particular data stream.

35. A method as in claim 34, wherein the step of (1)(ii) generating a client-side request to view a particular data stream comprises generating a request to view comprises a generating a request to view comprises a request to change or switch from a first current data stream to a second different data stream, media feed, media channel, media stream, video feed, or video channel.

36. A method as in claim 32, wherein the step of (1)(iv) generating a request to receive, comprises a request to join and optionally a request to leave a previous selection.

37. A method as in claim 36, wherein the source comprises a channel server of the identified one particular data stream.

38. A method as in claim 32, wherein the step of the client, for the new join request received from the server, querying a buffer list storing metadata related to the data stream, further comprising:

(i) determining the temporally nearest stand alone frame (SAF) in the buffer list (referred to as nSAF);

(ii) determining the nearest previous program clock reference or equivalent (PCR) in the buffer list with respect to the nSAF (referred as nPCR);

(iii) determining the nearest previous sequence information (SI) [dep-sequence parameter set (SPS), or sequence header (SH), or video sequence header, or other information that identifies the video properties with respect to the nSAF (referred as nSPS); and

(iv) determining the nearest previous program specific information (PSI) in the buffer list from either nPCR or nSPS whichever has greater distance with respect to the nRAP (referred as nPSI).

39. A method as in claim 32, wherein the predetermined timing conditions or constraints comprise a constraint that the nearest existing multicast group (referred as nMG) for the channel that satisfies constraints that:

(3)(i) contains a nearest previous program specific information (nPSI) at time greater than the time (Tc) at which a client request to join the channel is received plus the multicast join delay time for a client (Tmjd) or Tc+Tmjd;

(3)(ii) arrives at the nearest previous program specific information (nPSI) at a time in the future (Tm) for a multicast group to arrive at a stand-alone frame (SAF) represented by a time (Tr) of the immediate previous stand-alone frame SAF when a client attempts to join the channel represented by Tr in the channel data such that, the time in future Tm for a multicast group to arrive at a stand-alone frame (e.g. RAP) represented by Tr in the channel data is greater than a time Tc when the client request to join the channel is received and greater than or equal to the sum of (i) the time Tc when client request to join the channel is received plus the Multicast Joining Delay time Tmjd for a client plus the Multicast group creation interval or (Tc+Tmjd+MI)>

=Tm>

Tc).

40. A method as in claim 38, wherein the stand-alone frame (SAF) comprises one of a Random Access Point (RAP), a key frame, an IDR frame, and an I-frame.

41. A computer program stored on a computer readable media including executable computer program instructions for executing in a processor logic for performing the method of claim 32.

43. A method for switching between a plurality of cast groups, the method comprising:

on identifying a channel change request, the server finding the nearest RAP (nRAP);

the server finding the nearest PCR (nPCR);

the server finding the nearest sequence parameter set (nSPS);

determining whether Dist(nRAP, nSPS)>

Dist(nRAP, nPCR);

if Dist(nRAP, nSPS)>

Dist(nRAP, nPCR) is valid or true, then the server finding the nearest PSI (nPSI) from nSPS; and

if Dist(nRAP, nSPS)>

Dist(nRAP, nPCR) is not valid or false, then the server finding the nearest PSI (nPSI) from nPCR; and

the server then finding the nearest cast group (nMG) to nPSI which will contain nPSI in a time greater than Tmjd.

44. A method as in claim 43, wherein at least one of the plurality of cast groups comprises an advertisement.

45. A method as in claim 43, wherein at least one of the plurality of cast groups comprises a sports video stream or a movie.

46. A method as in claim 43, wherein the plurality of cast groups comprises a plurality of multicast groups.

47. A method as in claim 43, wherein the plurality of cast groups comprises a plurality of unicast groups.

48. A method for reducing switching delays between digital video feeds comprising:

using slotted transmission techniques for switching between at least two video streams.

49. A server system that reduces switching delays between digital video feeds comprising:

a switch implementing a slotted transmission logic for switching between at least two video streams.

51. A computer propagated data signal, comprising:

a first code segment including a first cast group; and

a second code segment including a second cast group that is the nearest cast group to the first cast group.

52. A computer propagated data signal as in claim 51, wherein the computer propagated data signal is embodied in a carrier wave.

53. A computer propagated data signal as in claim 51, wherein the computer propagated data signal comprises a digital television signal.

54. An article of manufacture comprising a digital video signal, the digital video signal including:

a first digital video signal content portion, a second digital video signal content portion, and a third digital video signal content portion;

a first transition portion between the first digital video signal content portion and the second digital video signal content portion being substantially free of artifacts; and

a second transition portion between the second digital video signal content portion and the third digital video signal content portion being substantially free of artifacts.

55. An article of manufacture as in claim 54, wherein the artifacts within the first and second transition portions may be any one or more of jitter, frozen frame, black screen, or lack of data.

56. An article of manufacture as in claim 54, wherein the first and second transition portions have a duration and the duration is limited by a known bound.

57. An article of manufacture as in claim 56, where the bounded duration is less than a duration perceptible to the unaided eye of a human observer.

58. An article of manufacture as in claim 56, where maximum delay in transitioning between the first and second signal is substantially 500 msec plus the time taken by the IGMP Leave and IGMP Join commands.

59. A system for performing a fast channel change operation comprising:

means for receiving an input data stream;

means for performing a data stream channel switching operation from a first data stream to a second data stream;

means for generating a plurality of output data streams, each of the output data streams having a substantially identical data but having a timing of the data in each of the output data streams that have a time shift relative to each of the other output data streams; and

means for communicating the plurality of output data streams to a client device over a first communication link.

60. A system as in claim 59, wherein the means for generating a plurality of output data streams includes a DSLAM.

61. An apparatus comprising:

a network input interface for receiving an input data stream;

an interconnect logic circuit for interconnecting or switching the input data stream with or to selected line card inputs;

a processor coupled with a memory and with the interconnect logic for executing program instructions; and

the processor including means for generating control instructions for generating a plurality of temporally modified data streams from the received input data stream, each of the plurality of temporally modified data streams having a substantially identical data content to the received data stream but having a different time delay relative to it.

62. An apparatus as in claim 61, wherein the apparatus is adapted to perform the functions of a digital subscriber line access multiplexer/demultiplexer (DSLAM).

63. An apparatus as in claim 61, wherein the data streams are multicast data streams.

64. An apparatus as in claim 61, wherein the means for generating control instructions comprises a computer program stored on a computer readable medium and executing within the processor.

65. An apparatus as in claim 61, wherein the plurality of temporally modified data streams are generated by the processor.

66. An apparatus as in claim 61, wherein the plurality of temporally modified data streams are generated by the interconnect logic.

67. An apparatus as in claim 61, wherein the plurality of temporally modified data streams are generated by the processor in combination with the interconnect logic.