Apparatus for system decoder and method for error correction of packet data

• US 7,131,048 B2
• Filed: 08/29/2001
• Issued: 10/31/2006
• Est. Priority Date: 07/10/2001
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yokoyama, Toru, Kimura, Junichi, Suzuki, Yoshinori
• Primary Examiner(s): Lamarre, Guy J.
• Application Number:
  US09/940,576
• Publication Number:
  US 20030014705A1
• Time in Patent Office: 1,889 Days
• Field of Search: 714/748, 714/775, 714/776, 375/240.27, 375/240.28, 348/469, 348/425.3, 370/471
• US Class Current: 714/748
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0082 fields explicitly indicating existence of error in data being transmitted, e.g. so that downstream stations can avoid decoding erroneous packet; relays
• CPC Class Codes: H04L 1/16 in which the return channel carries supervisory signals, e.g. repetition request signals
• CPC Class Codes: H04L 1/1838 for semi-reliable protocols, e.g. for less sensitive applications such as streaming video buffer level management for video bitstream receiver H04N21/44004
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards
• CPC Class Codes: H04N 19/89 involving methods or arrangements for detection of transmission errors at the decoder
• CPC Class Codes: H04N 21/41407 embedded in a portable device, e.g. video client on a mobile phone, PDA, laptop constructional details of equipment or arrangements specially adapted for portable computer application G06F1/1626; arrangements specially adapted for mobile receivers in broadcast systems H04H20/57
• CPC Class Codes: H04N 21/4382 Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/6131 involving transmission via a mobile phone network wireless downlink channel access H04W74/006
• CPC Class Codes: H04N 21/64322 IP

Abstract

When a non-error-resilient application decoder receives a data stream containing syntax error due to transmission errors, such as packet losses in wireless communication, an application decoder cannot usually continue decoding the stream data anymore. According to the present invention, the data stream containing syntax error along with error correction data generated by error-detectable transmission system is inputted into an error correction part before inputted into the application decoder. The error correction part detects the error position in the data stream using the error detection data, corrects the syntax error in the stream data, and generates a stream data which is possible to be decoded by the application decoder. As a result, the data stream containing syntax error can continue decoding or be decoded in better quality by a non-error-resilient application decoder, without adding any error correcting function in the existing application decoder.

Claims

1. A data correction method comprising steps of:

inputting a data stream of encoded data generated according to a coding syntax;

detecting an infonnation indicating a position of data error in the inputted data stream;

generating an error detection data corresponding to the detected information of data error position;

outputting the inputted data stream with the generated error detection data to an error correction processor;

identifying a type of a data in the inputted data stream, which corresponds to the error position indicated by the error detection data;

correcting the data error in the inputted data stream according to the identified type and complying with the coding syntax, thereby providing a corrected data stream complying with the coding syntax; and

outputting the corrected data stream to a decoder for decoding data included in the corrected data stream.

2. A data correction method according to claim 1, wherein the correcting step including steps of:

judging whether the error interval includes a first stream header;

deleting the first stream header data and data following the first stream header up to a subsequent stream header, if the error interval includes the first stream header, and the subsequent stream header does not contain any error such that data following the subsequent stream header is decodable.

3. A data correction method according to claim 1, wherein the correcting step including steps of:

judging whether the error interval includes a first frame header indicating bidirectionally predicted-coded frame;

deleting the first frame header and first frame data following the first frame header up to a start code of a subsequent frame, if the error interval includes the first frame header.

4. A data correction method according to claim 3, if the error interval does not include the first frame header, further comprising the steps of:

generating a substitute frame header using the subsequent frame header in a video packet data, if the first frame data including an error has a video packet data, which is data of a plurality of macroblocks with a frame header; and

setting a substitute frame including the error as a frame without encoded data and setting time information, if the first frame data including the error does not have a video packet data.

5. A data correction method according to claim 1, wherein the correcting step including steps of:

judging whether the error interval includes a first stream header and a first frame header which indicates bidirectionally predicted coded frame of a first video packet;

investigating a position of a macroblock and a number of encoded macroblocks of a subsequent video packet or both of the subsequent video packet and a preceding video packet, if the error interval includes both of the first stream header and the first frame header; and

correcting a position of a macroblock and a number of encoded macroblocks of the first video packet using the invested data.

6. A data correction method according to claim 5, wherein the macroblock correcting step includes setting a flag indicating that there is no encoded data in the macroblock of the first video packet.