Per-Image Forward Error Correction

• US 20120260145A1
• Filed: 04/07/2011
• Published: 10/11/2012
• Est. Priority Date: 04/07/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Yang, Yan, Jeong, Hyeonkuk, Abuan, Joe S., Zhou, Xiaosong
• Granted Patent: US 8,621,320 B2
• Time in Patent Office: Days
• US Class Current: 714/758
• CPC Class Codes: H03M 13/1102 Codes on graphs and decoding on graphs, e.g. low-density parity check [LDPC] codes
• CPC Class Codes: H03M 13/1505 Golay Codes
• CPC Class Codes: H03M 13/1515 Reed-Solomon codes
• CPC Class Codes: H03M 13/152 Bose-Chaudhuri-Hocquenghem [BCH] codes
• CPC Class Codes: H03M 13/19 Single error correction without using particular properties of the cyclic codes, e.g. Hamming codes, extended or generalised Hamming codes
• CPC Class Codes: H03M 13/356 Unequal error protection [UEP]
• CPC Class Codes: H03M 13/6312 Error control coding in combination with data compression
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/007 Unequal error protection for format H04L1/0078; for codes per se H03M13/35

Abstract

Some embodiments provide a method for encoding digital video. The method receives a digital video image. The method encodes the digital video image. The method generates error correction information for the encoded digital video image using only data from the encoded digital video image. The method transmits the generated error correction information with the encoded digital video image. In some embodiments, the method determines a level of error protection for the encoded digital video image based on an image type of the encoded digital video image.

Claims

1. A computer readable medium storing a computer program which when executed by at least one processor encodes digital video, the computer program comprising sets of instructions for:

receiving a digital video image;

encoding the digital video image;

generating error correction information for the encoded digital video image using only data from the encoded digital video image; and

transmitting the generated error correction information with the encoded digital video image.

2. The computer readable medium of claim 1, wherein the set of instructions for generating error correction information comprises sets of instructions for:

dividing the encoded digital video image into a plurality of data blocks; and

generating error correction information for the encoded digital video image using information from each of the data blocks.

3. The computer readable medium of claim 1, wherein the generated error correction information depends on an image type of the encoded digital video image and statistics of a network over which the encoded digital video image and error correction information is transmitted.

4. The computer readable medium of claim 1, wherein the set of instructions for transmitting comprises a set of instructions for transmitting only a portion of the generated error correction information, the portion dependent on an image type of the encoded digital video image and statistics of a network over which the encoded digital video image and error correction information is transmitted.

5. The computer readable medium of claim 1, wherein the digital video image is an image for a video-conference.

6. A computer readable medium storing a computer program which when executed by at least one processor encodes a digital video image, the computer program comprising sets of instructions for:

identifying an image type for an encoded digital video image;

determining a level of error protection for the encoded digital video image based on the identified image type;

generating error correction information for the encoded digital video image according to the level of error protection;

transmitting the generated error correction information with the encoded digital video image.

7. The computer readable medium of claim 6, wherein the image type is an I-frame that is encoded without reference to other digital video images.

8. The computer readable medium of claim 6, wherein the image type is one of a P-frame and a B-frame that is encoded by reference to at least one other digital video image.

9. The computer readable medium of claim 6, wherein more error correction information is generated when the digital video image is encoded without reference to other digital video images than when the digital video image is encoded by reference to at least one other digital video image.

10. The computer readable medium of claim 6, wherein the error correction information comprises parity bits.

11. The computer readable medium of claim 10, wherein the error correction information includes additional parity bits when the digital video image is encoded without reference to other digital video images.

12. The computer readable medium of claim 6, wherein the encoded digital video is transmitted via a network, the computer program further comprising a set of instructions for determining statistics of the network over which the encoded digital video is transmitted.

13. The computer readable medium of claim 12, wherein the set of instructions for determining the level of error protection accounts for the statistics of the network.

14. The computer readable medium of claim 13, wherein the set of instructions for determining the level of error protection comprises sets of instructions for:

increasing an amount of error correction information when a packet loss rate of the network increases; and

decreasing the amount of error correction information when the packet loss rate of the network decreases.

15. The computer readable medium of claim 13, wherein the set of instructions for determining the level of error protection comprises sets of instructions for:

increasing an amount of error correction information when a delay time of the network decreases; and

decreasing the amount of error correction information when the delay time of the network increases.

16. A computer readable medium storing a computer program which when executed by at least one processor encodes a digital video image, the computer program comprising sets of instructions for:

determining a packet size for transmitting an encoded video image over a network;

dividing the encoded video image into a plurality of data packets to transmit over the network based on the packet size;

determining a number of packets required to generate error correction information for the encoded video image;

when the required number of packets is greater than a number of data packets into which the video image is divided, creating additional pseudo-packets comprising known data;

generating error correction information for the encoded video image using the plurality of data packets and the created pseudo-packets; and

transmitting the plurality of data packets over the network with at least one error correction information packet.

17. The computer readable medium of claim 16, wherein the packet size is based on a maximum transmission unit of the network.

18. The computer readable medium of claim 16, wherein the encoded video image is divided into a minimum number of packets possible given the packet size.

19. The computer readable medium of claim 16, wherein the number of packets required to generate error correction information is based on a code length of an error correction algorithm used to generate the error correction information.

20. The computer readable medium of claim 19, wherein the number of packets is the largest whole number divisor of the code length.

21. The computer readable medium of claim 16, wherein the pseudo-packets comprise all zero bits.