METHOD TO SUPPORT FORWARD ERROR CORRECTION FOR REAL-TIME AUDIO AND VIDEO DATA OVER INTERNET PROTOCOL NETWORKS

• US 20090276686A1
• Filed: 12/21/2006
• Published: 11/05/2009
• Est. Priority Date: 12/21/2006
• Status: Active Grant

• Current Assignee: Thomson Licensing (Vantiva SA)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Li, Jun, Wu, Mingquan, Ma, Xiaojun, Liu, Hang, Champel, Mary-Luc, Zhang, Huanqiang
• Granted Patent: US 8,990,663 B2
• Time in Patent Office: Days
• US Class Current: 714/776
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0084 Formats for payload data

Abstract

A method and apparatus are described for protecting real time media including receiving media packets, generating media bit strings from the media packets, applying a forward error correcting code across the generated media bit strings to generate at least one forward error correcting bit string and generating at least one forward error correcting packet from the at least one forward error correcting bit string. Also described are a method and apparatus for recovering from losses of real time media packets including forming media bit strings from received media packets, forming forward error correcting bit strings from received forward error correcting packets, decoding the formed media bit strings and forward error correcting bit strings to obtain recovered media bit strings and recover lost media packets from the recovered media bit strings. Further described is a data structure for a forward error correcting header on computer readable media.

Claims

1. A method for protecting real time media, said method comprising:

receiving media packets;

generating media bit strings from said media packets;

applying a forward error correcting code across said generated media bit strings to generate at least one forward error correcting bit string; and

generating at least one forward error correcting packet from said at least one forward error correcting bit string.

2. The method according to claim 1, further comprising:

padding each of said generated media bit strings to a nearest multiple of symbols at a trailing end of each of said generated media bit strings; and

further padding at a trailing end of said previously padded bit string such that each padded bit string is a length of a longest bit string.

3. The method according to claim 1, wherein each of said media bit strings is generated by concatenating a set of fields from a real time transport protocol header, a payload length and a payload of each of said media packets in an order,

4. The method according to claim 3, further wherein said set of fields and said order comprises a marker bit, a payload type, a timestamp, a representation of a length of a media payload and said media payload.

5. The method according to claim 1, wherein each of said generated forward error correcting bit strings is used to fill in a forward error correction packet header

6. The method according to claim 5, further comprising:

inserting a predetermined number of low order bits of an index of said forward error correcting packet into a first index field of said forward error correction packet header;

inserting a predetermined number of higher order bits of said index of said forward error correcting packet into a second index field of said forward error correction packet header; and

setting a total number field of said forward error correction packet header to a predetermined number indicating a total number of forward error correcting packets and media packets in a forward error correcting block.

7. An apparatus for protecting real time media, comprising:

means for receiving media packets;

means for generating media bit strings from said media packets;

means for applying a forward error correcting code across said generated media bit strings to generate at least one forward error correcting bit string; and

means for generating at least one forward error correcting packet from said at least one forward error correcting bit string.

8. The apparatus according to claim 7, further comprising:

means for padding each of said generated media bit strings to a nearest multiple of symbols at a trailing end of each of said generated media bit strings; and

means for further padding at a trailing end of said previously padded bit string such that each padded bit string is a length of a longest bit string.

9. The apparatus according to claim 7, wherein each of said media bit strings is generated by concatenating a set of fields from a real time transport protocol header, a payload length and a payload of each of said media packets in an order.

10. The apparatus according to claim 9, further wherein said set of fields and said order comprises a marker bit, a payload type, a timestamp, a representation of a length of a media payload and said media payload.

11. The apparatus according to claim 7, wherein each of said generated forward error correcting bit strings is used to fill in a forward error correction packet header.

12. The apparatus according to claim 11, further comprising:

means for inserting a predetermined number of low order bits of an index of said forward error correcting packet into a first index field of said forward error correction packet header;

means for inserting a predetermined number of higher order bits of said index of said forward error correcting packet into a second index field of said forward error correction packet header; and

means for setting a total number field of said forward error correction packet header to a predetermined number indicating a total number of forward error correcting packets and media packets in a forward error correcting block.

13. A method for recovering from losses of real time media packets, said method comprising:

forming media bit strings from received media packets;

forming forward error correcting bit strings from received forward error correcting packets;

decoding said media bit strings and said forward error correcting bit strings to obtain recovered media bit strings; and

generating recovered media packets from said recovered media bit strings.

14. The method according to claim 13, further comprising padding said media bit strings at a trailing end of said media bit strings to a length of said forward error correcting bit strings.

15. An apparatus for recovering from losses of real time media packets, comprising:

means for forming media bit strings from received media packets;

means for forming forward error correcting bit strings from received forward error correcting packets;

means for decoding said media bit strings and said forward error correcting bit strings to obtain recovered media bit strings; and

means for generating recovered media packets from said recovered media bit strings.

16. The apparatus according to claim 15, further comprising means for padding said media bit strings at a trailing end of said media bit strings to a length of said forward error correcting bit strings.

17. A computer readable medium having stored thereon a data structure for a forward error correcting header, said data structure comprising a field for indicating a total number of forward error correcting packets and media packets.

18. A computer readable medium having stored thereon a data structure for a forward error correcting header, said data structure comprising a field for storing a predetermined number of a forward error correcting packet index.