Packet loss anticipation and pre emptive retransmission for low latency media applications
In many low latency media applications it is important to transmit media data packets from a media source to one or more media destinations as promptly as possible, while also ensuring that all media data packets that may be lost due to transmission errors are retransmitted and received correctly at the media destination. This invention described a system to do this with a system and methods for anticipating media data packet loss and making preemptive media data packet retransmission requests by dynamically computing a metric and decision logic for retransmission request that includes a need based factor from the media consuming application.
1. A system for low latency transport of media data over an IP network from a media source to a plurality of media destination devices, comprising:
an internet protocol communication network;
a media source device comprising a media transport source component and adapted to communicate with the communication network; and
a plurality of media destination devices each comprising a media transport destination component and a media consuming component and adapted to communicate with the communication network;
wherein the media transport source component sends media data in packets to a first media destination device using the communication network;
wherein the first media destination device receives the packets, places them in a collection, and uses the packets in the collection to provide media data to the media consuming component;
wherein the first media destination device detects a missing packet in the collection, computes a time delay for the missing packet, and uses the time delay to determine whether to ask the media source device to retransmit the missing packet; and
further wherein the first media destination device sends a requests for the retransmission of the missing packet to the media source device.
2. The system of claim 1 where the media source device identifies each said packet sent with a sequentially incrementing packet identifier; and
wherein the first media destination device detects missing packets by identifying a first packet having a highest packet identifier that has been received, detects a second packet that has not been received by identifying a packet identifier that is lower than the noted highest packet identifier for which no corresponding packet has been received; and classifies the second packet as a missing packet.
3. The system of claim 1 , wherein the determination to request a retransmission comprises the steps of computing a retransmission metric for the missing packet, comparing the retransmission metric to a threshold, and determining that a packet should be retransmitted if the retransmission metric is above the threshold.
4. The system of claim 1 , wherein the time delay for the missing packet is computed by subtracting, from a current time, the time that the latest packet, that has been received that possesses a packet identifier that is lower than the missing packet's packet identifier.
5. The system of claim 3 , wherein the media consuming component of the first media destination device provides a media data need value to the media destination device; and
wherein the first media destination device uses the media data need value in computing the retransmission metric for the missing packet.
6. The system of claim 1 , wherein the network is a home wireless network.
7. The system of claim 1 , wherein the media source device is a smart phone.
8. The system of claim 1 , wherein the media source device is an Internet service.
9. The system of claim 8 , wherein the Internet service is controlled by a mobile device of a user.
10. The system of claim 1 , wherein a plurality of media destination devices each receives a single media channel of a multichannel media object.
11. The system of claim 10 , wherein a first media channel is a video channel and a plurality of second media channels of the multichannel media object are a plurality of separate audio channels.
12. The system of claim 11 , wherein the plurality of separate audio channels collectively constitute a stereo or surround sound audio system.