Patent ID: 7995590

Claim:
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 corresponding to a raw 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; 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; 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; depacketizing the RTP packet by stripping off a RTP fixed header, generating one or more H.221 frames by placing the raw bitstream in a video portion of the one or more H.221 frames, and sending the one or more H.221 frames to the second gateway, if the first gateway can locate the PSC or the GBSC at the start portion of the RTP packet; receiving the H.221 frame containing the H.263-compressed video bitstream at the second gateway; setting a ‘bitsAvailable’ value to a number of H.263 video bits in the H.221 frame, wherein ‘bitsAvailable’ represents a number of video bits available in the H.221 frame to be packetized into one or more RTP packets at the second gateway; searching for a PSC or a GBSC in the H.221 frame at the second gateway; incrementing a value of ‘bitsAccum’ by 1 if the second gateway cannot locate the PSC or the GBSC in the H.221 frame at the second gateway, where ‘bitsAccum’ comprises a variable value that tracks a number of video bits in the H.221 frame that has already been packetized at the second gateway; determining whether ‘bitsAccum’ exceeds the MTU size of the underlying network; buffering the H.263 video bits in the H.221 frame if ‘bitsAccum’ does not exceed the MTU size of the underlying network; finding a bit offset where one of the one or more RTP packets at the second gateway should be fragmented if ‘bitsAccum’ does exceed the MTU size of the underlying network; and transmitting the one or more RTP packets at the second gateway to an endpoint.