METHOD AND SYSTEM FOR COMMUNICATING H.263 MACROBLOCK BOUNDARIES USING H.221 BAS FOR RFC2190-COMPLIANT FRAGMENTATION

• US 20080240123A1
• Filed: 03/27/2007
• Published: 10/02/2008
• Est. Priority Date: 03/27/2007
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Cutaia, Nicholas Joseph
• Granted Patent: US 7,995,590 B2
• Time in Patent Office: Days
• US Class Current: 370/401
• CPC Class Codes: H04L 65/103 in the network
• CPC Class Codes: H04L 65/65 Network streaming protocols, e.g. real-time transport protocol [RTP] or real-time control protocol [RTCP]

Abstract

A method includes receiving a Real-Time Transport Protocol (RTP) packet at a first gateway and translating the RTP packet into a H.221 frame. The H.221 frame includes a H.263-compressed video bitstream. The H.221 frame may also include a H.221 Bit-Rate Allocation Signal (BAS) message to communicate RFC2190-compliant fragmentation boundary information containing Macroblock (MB) boundary to a second gateway, if there is no picture start code (PSC) or Group of Block start code (GBSC) at a start portion of the RTP packet. The method further includes transmitting the H.221 frame from the first gateway to the second gateway; and fragmenting the H.263 video bitstream contained in the H.221 frame at a PSC, a GBSC, or a Macroblock (MB) boundary contained in the H.221 BAS fragmentation message.

Claims

1. A method comprising:

receiving a Real-Time Transport Protocol (RTP) packet at a first gateway, the RTP packet including a H.263-compressed video bitstream;

searching for a Picture Start code (PSC) or a Group of Block start code (GBSC) at a start portion of the RTP packet;

translating the RTP packet into a H.221 frame;

transmitting the H.221 frame containing the H.263-compressed video bitstream to a second gateway;

fragmenting the H.263-compressed video bitstream in the second gateway according to RFC2190; and

including in the H.221 frame a H.221 Bit-Rate Allocation Signal (BAS) fragmentation message containing a Macroblock (MB) boundary, if the first gateway cannot locate the PSC or the GBSC at the start portion of the RTP packet.

2. The method of claim 1, in which the RTP packet is encapsulated with a H.263 payload header followed by the H.263-compressed video bitstream according to RFC2190.

3. The method of claim 1, in which the first gateway and the second gateway are configured to translate from H.323 to H.320 and vice versa.

4. The method of claim 1, in which including in the H.221 frame a H.221 Bit-Rate Allocation Signal (BAS) fragmentation message containing a Macroblock (MB) boundary comprises generating a NS-comm H.221 BAS fragmentation message according to ITU-T Recommendation H.221 Appendix A Section A.9 (Escape table values).

5. The method of claim 4, in which the NS-comm H.221 BAS fragmentation message comprising:

a NS-comm field;

a temporal reference (TR) field indicating a specific picture in the H.263-compressed video bitstream to be fragmented at the Macroblock boundary; and

a Bit offset (BO) field indicating a number of bits from a Picture Start code (PSC) in which a fragmentation would occur.

6. The method of claim 4, in which the BO field is a 16-bit field.

7. The method of claim 4, in which the NS-comm field is set to FF.

8. The method of claim 1, in which fragmenting the H.263-compressed video bitstream in the second gateway comprises fragmenting the H.263-compressed video bitstream at one of a PSC, a GBSC, or the Macroblock (MB) boundary.

9. The method of claim 1, further comprising:

detecting a H.221 BAS fragmentation message at the second gateway, if any; and

storing the H.221 BAS fragmentation message in a queue in the second gateway;

10. The method of claim 1, further comprising translating the H.221 frame into one or more of a RFC2190 mode A RTP packet, a RFC2190 mode B RTP packet, and a RFC2190 mode C RTP packet at the second gateway.

11. The method of claim 1, further comprising communicating a Maximum Transmission Unit (MTU) size of an underlying network between the first gateway and the second gateway in a H.221 BAS channel using a non-ITU command.

12. A system comprising:

a first endpoint coupled to a first gateway via a first network, the first gateway being configured to;

receive a Real-Time Transport Protocol (RTP) packet;

translate the RTP packet into a H.221 frame, the H.221 frame including a H.263-compressed video bitstream;

include in the H.221 frame a H.221 Bit-Rate Allocation Signal (BAS) fragmentation message containing a Macroblock (MB) boundary, if the first gateway cannot locate a Picture Start code (PSC) or a Group of Block start code (GBSC) at a start portion of the RTP packet;

transmit the H.221 frame to a second gateway;

a second endpoint coupled to the second gateway via a second network; and

the first gateway and the second gateway coupled to each other via a circuit switched network.

13. The system of claim 12, in which the first endpoint and the second endpoint are H.323-compliant terminals.

14. The system of claim 12, in which the first gateway and the second gateway are configured to translate between H.323 and H.320 protocols.

15. The system of claim 12, in which the second gateway is configured to:

detect a H.221 BAS fragmentation message, if any;

store the H.221 BAS fragmentation message in a queue;

fragment the H.263-compressed video bitstream according to RFC2190; and

translate the H.221 frame into a RTP packet.

16. The system of claim 15, in which fragmenting the H.263-compressed video bitstream comprises fragmenting the H.263-compressed video bitstream at one of a PSC, a GBSC, or the Macroblock (MB) boundary.

17. The system of claim 15, in which translating the H.221 frame into a RTP packet comprises translating the H.221 frame into one or more of a RFC2190 mode A RTP packet, a RFC2190 mode B RTP packet, and a RFC2190 mode C RTP packet.

18. The system of claim 12, in which the first gateway and the second gateway are coupled to each other via a Public Switched Telephone Network (PSTN) or an Integrated Service Digital Network (ISDN).

19. Logic encoded in one or more tangible media for execution, and when executed on a machine, operable to:

receive a Real-Time Transport Protocol (RTP) packet at a first gateway;

translate the RTP packet into a H.221 frame, the H.221 frame including a H.263-compressed video bitstream;

include in the H.221 frame a H.221 Bit-Rate Allocation Signal (BAS) fragmentation message containing a Macroblock (MB) boundary, if the first gateway cannot locate a Picture Start code (PSC) or a Group of Block start code (GBSC) at a start portion of the RTP packet;

transmit the H.221 frame from the first gateway to the second gateway;

fragment the H.263 video bitstream at one of a PSC, a GBSC, or the Macroblock (MB) boundary according to RFC2190.

20. The logic of claim 19, in which including in the H.221 frame a H.221 Bit-Rate Allocation Signal (BAS) fragmentation message containing a Macroblock (MB) boundary comprises generating a NS-comm H.221 BAS fragmentation message according to ITU-T Recommendation H.221 Appendix A Section A.9 (Escape table values), the NS-comm H.221 message including:

a NS-comm field;

a temporal reference (TR) field indicating a specific picture in the H.263 video bitstream to be fragmented at a Macroblock boundary; and

a Bit offset (BO) Wield indicating number of bits from a picture start code (PSC) in which a fragmentation would occur.

21. The logic of claim 19, further operable to:

detect a H.221 BAS message at the second gateway, if any; and

store the H.221 BAS message in a queue in a RTP packetization module of the second gateway.

22. The logic of claim 19, further operable to translate the H.221 frame into one or more of a RFC2190 mode A RTP packet, a RFC2190 mode B RTP packet, and a RFC2190 mode C RTP packet.