Method and system for providing site independent real-time multimedia transport over packet-switched networks
First Claim
1. A system for providing site independent real-time multimedia transport over packet-switched networks comprising:
- a network;
a first node selected from a group of nodes wherein said first node is coupled with said network and wherein said first node comprises;
a packet store;
an automatic repeat request module coupled with said packet store;
a time clock; and
, a timing synchronizer configured to time stamp a first packet and a second packet obtained from said automatic repeat request module with a time parameter obtained from said time clock;
a plurality of second nodes selected from said group of nodes wherein said plurality of second nodes are coupled with said network and wherein said plurality of second nodes comprises;
a receiver time clock;
a receiver timing synchronizer coupled with said receiver time clock;
a clock recovery module coupled with said receiver timing synchronizer;
a receiver automatic repeat request buffer;
a receiver automatic repeat request module coupled with said receiver automatic repeat request buffer;
said first node configured to transmit to said plurality of said second nodes; and
, said plurality of second nodes configured to restore packet order, remove jitter and recover lost packets and where said each of said plurality of second nodes further comprise a network monitor configured to calculate and update a minimum hold time based on network jitter and round-trip time.
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Accused Products
Abstract
Embodiments of the invention enable minimum latency site independent real-time video transport over packet switched networks. Some examples of real-time video transport are video conferencing and real-time or live video streaming. In one embodiment of the invention, a network node transmits live or real-tine audio and video signals, encapsulated as Internet Protocol (IP) data packets, to one or more nodes on the Internet or other IP network. One embodiment of the invention enables a user to move to different nodes or move nodes to different locations thereby providing site independence. Site independence is achieved by measuring and accounting for the jitter and delay between a transmitter and receiver based on the particular path between the transmitter and receiver independent of site location. The transmitter inserts timestamps and sequence numbers into packets and then transmits them. A receiver uses these timestamps to recover the transmitter'"'"'s clock. The receiver stores the packets in a buffer that orders them by sequence number. The packets stay in the buffer for a fixed latency to compensate for possible network jitter and/or packet reordering. The combination of timestamp packet-processing, remote clock recovery and synchronization, fixed-latency receiver buffering, and error correction mechanisms help to preserve the quality of the received video, despite the significant network impairments generally encountered throughout the Internet and wireless networks.
301 Citations
19 Claims
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1. A system for providing site independent real-time multimedia transport over packet-switched networks comprising:
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a network;
a first node selected from a group of nodes wherein said first node is coupled with said network and wherein said first node comprises;
a packet store;
an automatic repeat request module coupled with said packet store;
a time clock; and
,a timing synchronizer configured to time stamp a first packet and a second packet obtained from said automatic repeat request module with a time parameter obtained from said time clock;
a plurality of second nodes selected from said group of nodes wherein said plurality of second nodes are coupled with said network and wherein said plurality of second nodes comprises;
a receiver time clock;
a receiver timing synchronizer coupled with said receiver time clock;
a clock recovery module coupled with said receiver timing synchronizer;
a receiver automatic repeat request buffer;
a receiver automatic repeat request module coupled with said receiver automatic repeat request buffer;
said first node configured to transmit to said plurality of said second nodes; and
,said plurality of second nodes configured to restore packet order, remove jitter and recover lost packets and where said each of said plurality of second nodes further comprise a network monitor configured to calculate and update a minimum hold time based on network jitter and round-trip time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for providing site independent real-time multimedia transport over packet-switched networks comprising:
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encapsulating multimedia data as a first packet and a second packet;
combining said first packet and said second packet into a stream of packets;
stamping said first packet and said second packet with a time stamp and a sequence number; and
,transmitting said stream of packets over an network to a plurality of receivers. - View Dependent Claims (14, 15)
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16. A method for providing site independent real-time multimedia transport over packet-switched networks comprising:
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stamping a first packet, a second packet and at least one forward error correction packet with a time stamp of a time of arrival;
recovering a transmitter clock;
buffering said first packet, said second packet and said at least one forward error correction packet;
ordering said first packet and second packet based on a sequence number in said first packet and said second packet;
holding said first packet and said second packet in a buffer for a fixed latency to compensate for calculated network jitter;
removing said first packet and said second packet from said buffer and placing said first packet and said second packet in an error correction buffer for a fixed time;
recovering a first lost packet;
requesting resend of a second lost packet; and
,displaying multimedia using data obtained from said first packet, said second data packet, said first lost packet and said second lost packet. - View Dependent Claims (17, 18, 19)
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Specification