Self-describing error correction of consolidated media content

Patent metadata

Field	Value
Publication number	US-9559805-B2
Application number	US-201414531015-A
Country	US
Kind code	B2
Filing date	Nov 3, 2014
Priority date	Nov 3, 2014
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

Abstract

Presented herein are downstream recovery (error correction) techniques for an aggregated/consolidated media stream. In one example, a consolidated media stream that includes source media packets from one or more sources is sent to one or more downstream receiving devices. Based on the source media packets, one or more self-describing recovery packets for downstream error correction of the source media packets are generated. The self-describing recovery packets include a mapping to the source media packets used to generate the self-describing recovery packets, thereby avoiding the addition of error correction information in the consolidated media stream. The one or more self-describing recovery packets are sent to each of the downstream receiving devices as a separate stream.

First claim

What is claimed is:

1. A method comprising:
obtaining one or more source media packets;
sending, to at least one downstream receiving device, a consolidated media stream that includes the source media packets and no error correction overhead;
generating, based on the source media packets, one or more self-describing recovery packets for downstream error correction of the source media packets, wherein the self-describing recovery packets include a mapping to the source media packets used to generate the self-describing recovery packets to avoid the addition of error correction overhead to the source packets of the consolidated media stream, wherein generating the one or more self-describing recovery packets for downstream error correction of the source media packets comprises:
composing a source block that includes the source media packets as source symbols;
generating one or more recovery source block headers that describe the composition of the source block, wherein the recovery source block header includes a count of source media streams referenced in the recovery source block header and, for each referenced source media stream, a stream reference describing the source media packets from that stream which are used in the source block, wherein a source media stream reference comprises a stream synchronization source identifier, a sequence number of the first packet from that source media stream referenced in this source block, and at least one of a count of contiguous packets or a bitmap which describes discontinuous packets; and
generating recovery symbols for the source media packets; and

sending the one or more self-describing recovery packets to the downstream receiving device.

2. The method of claim 1 , wherein the consolidated media stream sent to the downstream receiving device may be overlapping in composition with a consolidated media stream sent to an alternate downstream receiving device.

3. The method of claim 1 , wherein the use and degree of recovery symbols may be dynamically configured based on distribution loss conditions between a sending device and the downstream receiving device.

4. The method of claim 1 , wherein composing a source block comprises:
on a packet-by-packet basis, determining if any of the source media packets should be logically fragmented as two or more source symbols within the source block.

5. The method of claim 4 , wherein determining if any of the source media packets should be logically fragmented comprises:
determining whether or not a length of a transport header for a self-describing recovery packet, when combined with the length of a recovery source block header and a maximum length of the recovery payload, exceeds a predetermined maximum packet length.

6. The method of claim 4 , wherein determining if any of the source media packets should be logically fragmented comprises:
identifying a distribution for the lengths of the source media packets and correlated the size of the source symbols in the source block with the identified distribution of the source media packet lengths.

7. The method of claim 4 , wherein the application of logical fragmentation to each source media packet is described by a compact map in the recovery source block header.

8. The method of claim 4 , further comprising applying logical fragmentation to each source media packet that is described by an ordered presentation of first and second fragments, enabling the determination of packet lengths in a split recovery process without the use of an explicit fragmentation map.

9. The method of claim 1 , wherein generating the recovery symbols for the source media packets comprises:
performing forward error correction (FEC) encoding of the source media packets.

10. The method of claim 1 , wherein the downstream receiving device is a mid-point device located upstream from an endpoint device, and wherein the method further comprises:
decoding the self-describing recovery packets to perform error correction of the source media packets and to generate a set of error corrected source media packets;
generating a consolidated media stream that includes the error corrected source media packets;
generating, based on the error corrected source media packets, one or more further self-describing recovery packets for downstream error correction of the error corrected source media packets, wherein the additional self-describing recovery packets include a mapping to the error corrected source media packets;
sending the consolidated media stream that includes the error corrected source media packets to a second downstream receiving device; and
sending the one or more additional self-describing recovery packets to the second downstream receiving device.

11. An apparatus comprising:
one or more network interface devices;
a memory; and
a processor coupled to the memory and the network interface devices, wherein the processor:
obtains one or more source media packets,
sends, to at least one downstream receiving device, a consolidated media stream that includes the source media packets and no error correction overhead;
generates, based on the source media packets, one or more self-describing recovery packets for downstream error correction of the source media packets, wherein the self-describing recovery packets include a mapping to the source media packets used to generate the self-describing recovery packets to avoid the addition of error correction overhead to the source packets of the consolidated media stream, wherein to generate the one or more self-describing recovery packets for downstream error correction of the source media packets, the processor:
composes a source block that includes the source media packets as source symbols;
generates one or more recovery source block headers that describe the composition of the source block, wherein the recovery source block header includes a count of source media streams referenced in the recovery source block header and, for each referenced source media stream, a stream reference describing the source media packets from that stream which are used in the source block, wherein a source media stream reference comprises a stream synchronization source identifier, a sequence number of the first packet from that source media stream referenced in this source block, and at least one of a count of contiguous packets or a bitmap which describes discontinuous packets; and
generates recovery symbols for the source media packets; and
sends the one or more self-describing recovery packets to the downstream receiving device.

12. The apparatus of claim 11 , wherein to compose a source block, the processor:
determines, on a packet-by-packet basis, if any of the source media packets should be logically fragmented as two or more source symbols within the source block.

13. The apparatus of claim 12 , wherein the application of logical fragmentation to each source media packet is described by a compact map in the recovery source block header.

14. The apparatus of claim 12 , wherein the processor is configured to apply a logical fragmentation to each source media packet that is described by an ordered presentation of first and second fragments, enabling the determination of packet lengths in a split recovery process without the use of an explicit fragmentation map.

15. The apparatus of claim 11 , wherein the downstream receiving device is a mid-point device located upstream from an endpoint device, and wherein the processor further:
decodes the self-describing recovery packets to perform error correction of the source media packets and to generate a set of error co

Assignees

• Cisco Tech Inc

Inventors

• Bright-Thomas Paul G
• Hakonsen Greg
• Sandbakken Geir
• Prior William Geoffrey
• Caramma Marcello
• Ramalho Michael A

Classifications

• H04L65/608

  Electricity · mapped topic

• G06F11/10

  Adding special bits or symbols to the coded information, e.g. parity check, casting out 9's or 11's · CPC title

• H04L1/0042

  Encoding specially adapted to other signal generation operation, e.g. in order to reduce transmit distortions, jitter, or to improve signal shape (H04L1/0067 takes precedence) · CPC title

• H04L65/607

  Electricity · mapped topic

• H04L1/0076

  Distributed coding, e.g. network coding, involving channel coding (coding in both space and time H04L1/0618; cooperative diversity H04B7/022) · CPC title