Data receiving apparatus and method

a data receiving and data technology, applied in the direction of synchronisation signal speed/phase control, television system, coding, etc., can solve the problems of long time-consuming and laborious, no effective and satisfactory research in this field, and the failure to detect the start code in the data stream

Inactive Publication Date: 2005-11-08
MITSUBISHI ELECTRIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0033]The method may further include the step of ceasing the error masking and resuming block data decoding when a start code is detected corresponding to a layer which is the same as or higher in the layer hierarchy than the layer in which no selection was made.
[0034]The selecting step may include generating a replacement start signal if one of the expected start codes does not match the start code correspondin

Problems solved by technology

Successful detection of a start code in a data stream has long been a challenge.
However, no effective and satisfactory research has been conducted in this field.
The error detection may lead to a suspension of an operation.
Consequently, the conventional start code decoder cannot effectively deal with a data stream with two or more types of start codes which are to be detected or identified.
However, the conventional method is of no use for the detection of a start code value which can be a plurality of values, some of which differ from one another by one bit.
Application of the conventional method to a start code detection with this coded data stream may cause serious decoding damage in a decoder.

Method used

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Examples

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embodiment 1

[0082]FIG. 1 shows a decomposition of a video sequence of MPEG-1 video data with different data elements in layers. A decoder of the present invention is intended primarily to decode digital video data in a layered bit stream according to the method prescribed by ISO / IEC 11172-2 (MPEG-1).

[0083]With reference to FIG. 1, a video sequence consists of one or more groups of pictures or GOPs. A GOP is a series of one or lore pictures. A picture contains one or more slices. A slice is a series of two or more macroblocks. A macroblock is a plurality of blocks. Thus, digital video data are organized by hierarchical levels of data or in layers. A top level in hierarchy in the video sequence is a sequence layer. The next level in the hierarchy is a GOP layer followed by a picture layer. A picture layer is followed by a slice layer. A macroblock layer follows a slice layer and the lowest level in the hierarchy is a block layer following a macroblock layer.

[0084]A bit stream of coded video data ...

embodiment 4

[0151]With further reference to FIG. 16, a decoder of the present invention can have a start code replacement unit which prioritizes layer based expected start codes. FIG. 20 is a block diagram of a start code replacement unit 31a. The embodiment of FIG. 20 is similar the embodiment of FIG. 16, except that the similarity calculator 32 and the similarity based replacement identifier 34 are replaced by a priority assigning numerator 37 and a priority based replacement identifier 39, respectively.

[0152]The start code replacement unit 31a according to this embodiment selects a replacement start code based on a priority based evaluation of layer based expected start codes. Layer based expected start codes in FIG. 10 are prioritized in order of their expectation of occurrence in the bit stream. Each of the layer based expected start codes is assigned a numerical value based on its probability of occurrence.

[0153]FIG. 21 shows a block diagram of the priority assigning numerator 37 where th...

embodiment 5

[0160]With further reference to the evaluation memory table 40 in the priority assigning numerator 37 in FIG. 21, the probability of occurrence can be assigned a priority number in descending or ascending order from the highest or lowest probability of occurrence rather than a value of the probability of occurrence. FIG. 25 shows another example of the evaluation memory table 40. According to this embodiment, each of the layer based expected start codes is given a priority number in descending order from the highest expectation of occurrence. According to the table in FIG. 25, the group_start_code is the first in the priority order, the extension_data_start_code is the second in the priority order and the user_data_start_code is the third in the priority order when the latest layer is a sequence.

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Abstract

The present invention is to provide a decoder which detects a start code in a layered coded data stream on a layer basis for improving an error detecting function to reduce possible damaging effects, and replaces a detected start code with minor error by an appropriate start code to maintain decoding.The decoder includes a unique pattern detector which detects a start code pattern in a layered coded data stream, a start code identifier which identifies the detected start code pattern based on a given condition, a similarity calculator which calculates similarity as an evaluation between the error detected start code pattern and an expected start code based on layer, and a similarity based replacement identifier which replaces the error detected start code pattern by the most appropriate replacement selected based on the similarity based evaluation, and otherwise the priority based replacement identifier which selects a replacement by the priority order.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a data receiving method and apparatus, and more specifically to a decoder which deals with a coded data stream in a regularly organized layered structure of user information including video, audio, data and so forth.[0003]2. Description of the Related Art[0004]It has been a common practice to use a start code as a signal for synchronization or for execution startup of a process. Successful detection of a start code in a data stream has long been a challenge. It is also important to deal successfully with a situation where a start code pattern is detected by error and, particularly, to maintain a decoding operation without interruption by an error detection. However, no effective and satisfactory research has been conducted in this field.[0005]Japanese Unexamined Patent Publication No. 288129 / 1989 discloses a conventional system which tries to detect a start code of a fixed bit pattern wi...

Claims

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Application Information

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IPC IPC(8): H03M13/00H04L29/06H04L7/08H04N7/24H04N7/52H04N7/56H04N19/00H04N19/895
CPCH04N7/52H04N7/56H04N21/238H04N19/895
InventorSEKIGUCHI, SHUN-ICHIMURAKAMI, TOKUMICHIKATO, YOSHIAKI
OwnerMITSUBISHI ELECTRIC CORP