Low latency data encoder

• US 6,725,412 B1
• Filed: 08/15/2000
• Issued: 04/20/2004
• Est. Priority Date: 08/15/2000
• Status: Expired due to Term

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Smithers, Michael J., Gundry, Kenneth J., Vernon, Stephen D., Truman, Michael M.
• Primary Examiner(s): Decady, Albert
• Assistant Examiner(s): Britt, Cynthia
• Application Number:
  US09/639,012
• Time in Patent Office: 1,344 Days
• Field of Search: 714/758
• US Class Current: 714/758
• CPC Class Codes: G11B 20/1803 by redundancy in data representation
• CPC Class Codes: H03M 13/09 Error detection only, e.g. using cyclic redundancy check [CRC] codes or single parity bit

Abstract

Codeword-position-caused encoder latency is reduced by avoiding the requirement for knowledge of the message prior to generating an error detecting or concealing codeword associated with the message. A pseudo error detecting or concealing codeword is inserted in place of the normal error detecting or concealing codeword appropriate for the segment of information to which the error detecting or concealing codeword relates. In order to satisfy the requirement of conventional decoders, the pseudo error detecting or concealing information must match or be appropriate for the segment so that the decoder sees the codeword and message segment as valid or error free. This is accomplished by modifying or perturbing at least a portion of the segment to which the pseudo codeword relates. The invention is particularly useful for maintaining the backward compatibility of audio data encoding formats in which the minimum latency is too long (e.g., computer games, where the player performs some operation leading to a sound, and that sound must not be perceptibly delayed with respect to the operation).

Claims

1. A method for reducing latency in the transmission of coded information relative to received information, wherein

the coded information includes error detecting or concealing information valid for said coded information,

the coded information further includes an encoded version of said received information or a modified form of an encoded version of said received information,

the coded information optionally includes auxiliary information that may include null bits, and

wherein the coded information is transmitted in a format in which at least some of the error detecting or concealing information has an assigned position or positions that do not follow all of said encoded version of the received information or said modified form of said encoded version of the received information,

comprising generating said coded information, which coded information includes pseudo error detecting or concealing information that is not valid for said encoded version of said received information or for said encoded version of said received information and said optional auxiliary information, wherein said generating includes at least one of

a) modifying an encoded version of said received information in a manner that affects the validity of the error detecting or concealing information, and

b) modifying said auxiliary information in a manner that affects the validity of the error detecting or concealing information,

so that said pseudo error detecting or concealing information is valid for said coded information, and

transmitting said coded information, whereby the transmission of coded information may begin before all of said received information is received.

2. A method according to claim 1 wherein said pseudo error detecting or concealing information is in the form of at least one error correcting or concealing codeword.

3. A method according to claim 2 wherein said codeword is in the form of at least one error detecting cyclic redundancy check (CRC) word.

4. A method according to any one of claims 1, 2, or 3 wherein said error detecting or concealing information has an assigned position preceding an encoded version of said received information or a modified form of an encoded version of said received information.

5. A method according to any one of claims 1, 2, or 3 wherein said error detecting or concealing information has an assigned position between the beginning and end of an encoded version of said received information or a modified form of an encoded version of said received information.

6. A method according to claim 1 wherein said pseudo error detecting or concealing information is arbitrary.

7. A method according to claim 6 wherein said pseudo error detecting or concealing information is a random number or a pseudo-random number.

8. A method according to claim 1 wherein said pseudo error detecting or concealing information conveys information.

9. A method for reducing latency in the transmission of coded information relative to received information, wherein the coded information is formatted into a frame that includes an encoded version of said received information or a modified form of an encoded version of said received information and a cyclic redundancy check (CRC) word having an assigned position preceding the encoded version of the received information or a modified form of the encoded version of the received information and that is valid for coded information in a first portion of the frame, comprising

generating said coded information, which coded information includes at least one pseudo CRC word in the position of and in place of said CRC word, said pseudo CRC word not being valid for the coded information in said first portion of the frame, wherein said generating generates the coded information in the first portion of the frame after said pseudo CRC word so that the pseudo CRC word is valid for the first portion of the frame, and

transmitting said coded information, whereby the transmission of coded information may begin before all of said received information is received.

10. A method according to claim 9 wherein two additional CRC words are generated and inserted in the first portion of the frame and after said pseudo CRC word.

11. A method according to claim 10 wherein the additional CRC word occurring first in the frame is a forward generated CRC word and the additional CRC word occurring second in the frame is a reverse generated CRC word.

12. A method according to claim 9 or claim 10 wherein said at least one additional CRC word is carried in auxiliary information.

13. A method according to claim 9 wherein said pseudo CRC word is a random number or a pseudo-random number.

14. A method according to claim 9 wherein said pseudo CRC word conveys information.