Retransmission-based stream repair and stream join
First Claim
1. A method comprising:
- receiving a multicast media stream at a media retransmission device;
caching the multicast media stream in a local media cache at the media retransmission device, wherein the media retransmission device shares an IP address with at least one other media retransmission device, and wherein the shared IP address is for addressing retransmission requests from at least one media stream receiver;
receiving a unicast Internet Protocol (IP) request from the at least one media stream receiver for retransmission of the cached multicast media stream, wherein the retransmission request is directed to the media retransmission device according to an IP topology relationship between the media retransmission device and the at least one media stream receiver, and wherein the retransmission requests are Real-Time Transport Control Protocol (RTCP) Negative Acknowledgement (NACK) packets that include the shared IP address as a destination address;
sending a unicast IP message to the requesting media stream receiver to dynamically instantiate a unicast Real Time Transport (RTP) repair session; and
unicasting a cached requested portion of the multicast media stream to the media stream receiver.
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Abstract
The Real-time Transport Protocol (RTP) and its related standards define a retransmission packet format and a way to give feedback via Negative ACKnowledge (NACK) packets for data that has been lost. In one embodiment, a unicast RTP repair session is associated with a main Source Specific Multicast (SSM) multicast session. Real-time Transport Control Protocol (RTCP) NACK packets are then used for feedback to a SSM feedback target address. This dynamically instantiates unicast RTP repair for multicast sessions. The repair scheme can be used for repairing multicast channels or joining new multicast channels. In another embodiment, a media transmission device shares an IP address with one or more other media transmission devices. The shared IP address can also be used to route multiple identical multicast media streams to different media stream receivers.
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Citations
14 Claims
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1. A method comprising:
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receiving a multicast media stream at a media retransmission device; caching the multicast media stream in a local media cache at the media retransmission device, wherein the media retransmission device shares an IP address with at least one other media retransmission device, and wherein the shared IP address is for addressing retransmission requests from at least one media stream receiver; receiving a unicast Internet Protocol (IP) request from the at least one media stream receiver for retransmission of the cached multicast media stream, wherein the retransmission request is directed to the media retransmission device according to an IP topology relationship between the media retransmission device and the at least one media stream receiver, and wherein the retransmission requests are Real-Time Transport Control Protocol (RTCP) Negative Acknowledgement (NACK) packets that include the shared IP address as a destination address; sending a unicast IP message to the requesting media stream receiver to dynamically instantiate a unicast Real Time Transport (RTP) repair session; and unicasting a cached requested portion of the multicast media stream to the media stream receiver. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. Software encoded on a non-transitory computer-readable media and when executed operable to:
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cache an Internet Protocol (IP) transmitted media stream at a media retransmission device, wherein the media retransmission device shares an IP address with at least one other media retransmission device and wherein the shared IP address is for addressing retransmission requests from at least one media stream receiver; identify the shared IP address to the at least one receiver receiving the media stream, wherein the shared IP address is associated with the media stream; receive a retransmission request addressed to the shared IP address, wherein the retransmission request is directed to the media retransmission device according to an IP topology relationship between the media retransmission device and the at least one media stream receiver, and wherein the retransmission requests are Real-Time Transport Control Protocol (RTCP) Negative Acknowledgement (NACK) packets that include the shared IP address a destination address; identify the retransmission request as a media stream repair request; and responsive to identifying the media stream repair request, send a portion of the cached media stream indicated as lost or corrupted in the repair request; wherein the repair request dynamically instantiates a unicast RTP repair session with a requesting receiver. - View Dependent Claims (9, 10, 11, 12, 13)
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14. Logic encoded on a non-transitory tangible media for execution and when executed operable to:
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cache an Internet Protocol (IP) transmitted media stream at a media retransmission device, wherein the media retransmission device shares an IP address with at least one other media retransmission device and wherein the shared IP address is for addressing retransmission requests from at least one media stream receiver; identify the shared IP address to the at least one media stream receiver receiving the media stream; receive a retransmission request addressed to the shared IP address, wherein the retransmission request is directed to the media retransmission device according to an IP topology relationship between the media retransmission device and the at least one media stream receiver, and wherein the retransmission requests are Real-Time Transport Control Protocol (RTCP) Negative Acknowledgement (NACK) packets that include the shared IP address a destination address; identify the retransmission request as a channel join request; and responsive to identifying the channel join request, send a portion of the cached media stream to the receiver, wherein the join request dynamically instantiates a unicast RTP repair session with a requesting receiver for sending decoder information and a group of cached media stream frames required for decoding a new media stream.
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Specification