Method to support forward error correction for real-time audio and video data over internet protocol networks

• US 8,990,663 B2
• Filed: 12/21/2006
• Issued: 03/24/2015
• Est. Priority Date: 12/21/2006
• Status: Active Grant

• Current Assignee: Thomson Licensing (Vantiva SA)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Liu, Hang, Champel, Mary-Luc, Wu, Mingquan, Ma, Xiaojun, Zhang, Huanqiang, Li, Jun
• Primary Examiner(s): PATEL, JIGAR P
• Application Number:
  US12/448,156
• Publication Number:
  US 20090276686A1
• Time in Patent Office: 3,015 Days
• Field of Search: 714/776
• 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;

re-ordering said media packets to form a two dimensional matrix of a number of columns and a number of rows;

generating media bit strings from said media packets;

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;

further padding at a trailing end of said previously padded bit strings such that each padded bit string has a length of the longest bit string;

applying a forward error correcting code across said generated media bit strings to generate a plurality of forward error correcting bit strings;

generating forward error correcting packets from said forward error correcting bit strings; and

transmitting said generated forward error correcting packets, said forward error correcting packets separated by a dimension of said two dimensional matrix of said media packets which served as a basis for generation of said forward error correcting packets, wherein said forward error correcting packets are generated without changing a format of said media packets and are transmitted separately from said media packets using different port than a port used to transmit said media packets enabling non-forward error correcting systems to receive and recover said media packets.

2. 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.

3. The method according to claim 2, 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.

4. 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.

5. The method according to claim 4, 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.

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

means for receiving media packets;

means for re-ordering said media packets to form a two dimensional matrix of a number of columns and a number of rows;

means for generating media bit strings from said media packets;

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;

means for further padding at a trailing end of said previously padded bit strings such that each padded bit string has a length of the longest bit string;

means for applying a forward error correcting code across said generated media bit strings to generate a plurality of forward error correcting bit string;

means for generating forward error correcting packets from said forward error correcting bit strings; and

means for transmitting said generated forward error correcting packets, said forward error correcting packets separated by a dimension of said two dimensional matrix of said media packets which served as a basis for generation of said forward error correcting packets, wherein said forward error correcting packets are generated without changing a format of said media packets and are transmitted separately from said media packets using a different port than a port used to transmit said media packets enabling non-forward error correcting systems to receive and recover said media packets.

7. The apparatus according to claim 6, 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.

8. The apparatus according to claim 7, 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.

9. The apparatus according to claim 6, wherein each of said generated forward error correcting bit strings is used to fill in a forward error correction packet header.

10. The apparatus according to claim 9, 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.

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

re-ordering received media packets to form a two-dimensional matrix of a number of columns and a number of rows of received media packets;

forming media bit strings from received and re-ordered media packets;

forming forward error correcting bit strings from received forward error correcting packets, wherein said forward error correcting packets are generated without changing a format of said media packets and are transmitted separately from said media packets using a different port than a port used to transmit said media packets enabling non-forward error correcting systems to receive and recover said media packets;

padding said media bit strings to the length of the forward error correcting bit strings;

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.

12. The method according to claim 11, further comprising removing padding said media bit strings at a trailing end of said media bit strings to a length of said forward error correcting bit strings.

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

means for re-ordering received media packets to form a two-dimensional matrix of a number of columns and a number of rows of received media packets;

means for forming media bit strings from received media packets;

means for forming forward error correcting bit strings from received forward error correcting packets, wherein said forward error correcting packets are generated without changing a format of said media packets and are transmitted separately from said media packets using a different port than a port used to transmit said media packets enabling non-forward error correcting systems to receive and recover said media packets;

means for removing padding said media bit strings to the length of the forward error correcting bit strings;

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

means for generating recovered media packets from said recovered media bit strings; and

means for re-ordering said recovered media packets to form a two dimensional matrix of a number of columns and a number of rows of recovered media packets.

14. The apparatus according to claim 13, further comprising means for removing 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 protecting real time media, comprising:

a real time transport protocol packetization module, said real time transport protocol packetization module receiving media packets;

said real time transport protocol packetization module re-ordering said media packets to form a two dimensional matrix of a number of columns and a number of rows;

said real time transport protocol packetization module generating media bit strings from said media packets;

said real time transport protocol packetization module 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;

said real time transport protocol packetization module further padding at a trailing end of said previously padded bit strings such that each padded bit string has a length of the longest bit string;

a forward error correction encoding and packetization module, said forward error correction encoding and packetization module applying a forward error correcting code across said generated media bit strings to generate a plurality of forward error correcting bit string, said forward error correction encoding and packetization module in communication with said real time transport protocol packetization module;

said forward error correction encoding and packetization module generating forward error correcting packets from said forward error correcting bit strings; and

a user datagram protocol and internet packet stack and network interface module, said a user datagram protocol and internet packet stack and said network interface module transmitting said generated forward error correcting packets, said forward error correcting packets separated by a dimension of said two dimensional matrix of said media packets which served as a basis for generation of said forward error correcting packets, wherein said forward error correcting packets are generated without changing a format of said media packets and are transmitted separately from said media packets using a different port than a port used to transmit said media packets enabling non-forward error correcting systems to receive and recover said media packets, said a user datagram protocol and internet packet stack in communication with said network interface module, said a user datagram protocol and internet packet stack also in communication with said forward error correction encoding and packetization module.

16. The apparatus according to claim 15, 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.

17. The apparatus according to claim 16, 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.

18. The apparatus according to claim 15, wherein each of said generated forward error correcting bit strings is used to fill in a forward error correction packet header.

19. The apparatus according to claim 18, further comprising:

said forward error correction encoding and packetization module 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;

said forward error correction encoding and packetization module 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

said forward error correction encoding and packetization module 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.

20. The apparatus according to claim 15, further comprising a storage 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, wherein said forward error correcting packets are generated without changing a format of said media packets and are transmitted and received separately from said media packets using a different port than a port used to transmit said media packets enabling non-forward error correcting systems to receive and recover said media packets.

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

a forward error correction encoding and packetization module, said forward error correction encoding and packetization module re-ordering received media packets to form a two-dimensional matrix of a number of columns and a number of rows of received media packets;

said forward error correction encoding and packetization module forming media bit strings from received media packets;

said forward error correction encoding and packetization module forming forward error correcting bit strings from received forward error correcting packets, wherein said forward error correcting packets are generated without changing a format of said media packets and are transmitted separately from said media packets using a different port than a port used to transmit said media packets enabling non-forward error correcting systems to receive and recover said media packets;

a real time transport protocol packetization module, said real time transport protocol packetization module removing padding said media bit strings to the length of the forward error correcting bit strings, said real time transport protocol packetization module in communication with said forward error correction encoding and packetization module;

said real time transport protocol packetization module decoding said media bit strings and said forward error correcting bit strings to obtain recovered media bit strings;

said real time transport protocol packetization module generating recovered media packets from said recovered media bit strings; and

said real time transport protocol packetization module re-ordering said recovered media packets to form a two dimensional matrix of a number of columns and a number of rows of recovered media packets.

22. The apparatus according to claim 21, further comprising said real time transport protocol packetization module removing padding said media bit strings at a trailing end of said media bit strings to a length of said forward error correcting bit strings.

23. The apparatus according to claim 21, further comprising a storage 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, wherein said forward error correcting packets generated without changing a format of said media packets and are transmitted and received separately from said media packets using a different port than a port used to transmit said media packets enabling non-forward error correcting systems to receive and recover said media packets.