Bit stream analyzing method and apparatus

• US 6,185,339 B1
• Filed: 09/22/1998
• Issued: 02/06/2001
• Est. Priority Date: 09/24/1997
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Ozaki, Nozomu
• Primary Examiner(s): Couso, Jose L.
• Application Number:
  US09/158,034
• Time in Patent Office: 868 Days
• Field of Search: 382/232, 382/236, 382/238, 382/240, 382/242, 382/248, 382/250, 358/432, 358/433, 348/384, 348/394, 348/395, 348/400-404, 348/407-416, 348/420-421, 348/425, 348/430, 348/431, 348/699
• US Class Current: 382/232
• CPC Class Codes: H04N 19/423 characterised by memory arrangements H04N19/433 takes precedence
• CPC Class Codes: H04N 19/436 using parallelised computational arrangements
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/91 Entropy coding, e.g. variable length coding [VLC] or arithmetic coding
• CPC Class Codes: H04N 21/426 Internal components of the client ; Characteristics thereof H04N5/44 takes precedence

Abstract

The present invention enables to enhance a processing performance in analyzing a bit stream of decoding a variable-length code to be successively processed.

The present invention provides an MPEG video decoder for decoding an MPEG video stream including: a pre-purser 3 (bit stream divider) for detecting a slice start code of Slice layer and dividing a bit stream into two sub streams; video decoders 9 and 10 for decoding the sub streams separately from each other; a memory controller (memory interface) for combining with consistency the decoded data from the video decoders 9 and 10; and an external memory 4.

Claims

1. A bit stream analyzing method for analyzing a video bit stream of MPEG encoded data comprising the steps of:

detecting a slice header code for each slice unit of the MPEG encoded video bit stream;

dividing said bit stream into a plurality of sub streams according to the detection of said slice header code;

decoding said plurality of sub streams separately from each other; and

combining said plurality of sub streams which have been decoded into a decoded video bit stream.

2. A bit stream analyzing method as claimed in claim 1, said method further comprising:

a step of continuously repeating a predetermined operation by a predetermined number of times after detection of said specific pattern;

a step of carrying out decode operation if no error has occurred in said continuous predetermined operations, and

a step of detecting said specific code pattern from a new position if an error has occurred in said continuous predetermined operations.

3. A bit stream analyzing apparatus for analyzing a video bit stream of MPEG encoded data comprising:

detecting means for detecting a slice header code for each slice unit of the MPEG encoded video bit stream;

dividing means for dividing said bit stream into a plurality of sub streams according to the detection of said slice header code;

decoding means for decoding said plurality of sub streams separately from each other; and

control means for combining said plurality of sub streams which have been decoded into a decoded video bit stream.

4. A bit stream analyzing apparatus as claimed in claim 3, wherein a predetermined operation is repeated by a predetermined number of times after detection of said specific pattern;

and if no error has occurred in said continuous predetermined operations, a decode operation is carried out, and if an error has occurred in said continuous predetermined operations, detection of said specific code pattern is tried again from a new position.

5. A bit stream analyzing method for analyzing a bit stream containing a Huffman-coded compressed data, said method comprising:

a first decode step for decoding said bit stream, starting at a head of said bit stream;

a match detection step for shifting a data in the middle of said bit stream so as to be compared with a Huffman table to detect whether a match is present;

a boundary detection step for detecting a boundary of a Huffman code according to a result of said match detection;

a second decode step for decoding a data starting at said boundary position of said bit stream; and

a combine step for combining a result of said first decode step starting at the head of said bit stream with a result of said second decode step starting at said boundary position of said bit stream.

6. A bit stream analyzing method as claimed in claim 5, wherein said match detection step is carried out by simultaneous comparison with a plurality of types of Huffman tables so that a matched Huffman table is used for continuing the match detection within a predetermined range and if an error is caused in the match detection in said predetermined range, control is returned to said step of one-bit shift and comparison with a Huffman table.

7. A bit stream analyzing apparatus for analyzing a bit stream containing a Huffman-coded compressed data, said apparatus comprising:

first decode means for decoding said bit stream, starting at a head of said bit stream;

match detection means for shifting a data in the middle of said bit stream so as to be compared with a Huffman table to detect whether a match is present;

boundary detection means for detecting a boundary of a Huffman code according to a result of said match detection;

second decode means for decoding a data starting at said boundary position of said bit stream; and

combine means for combining a result of said first decode step starting at the head of said bit stream with a result of said second decode step starting at said boundary position of said bit stream.

8. A bit stream analyzing apparatus as claimed in claim 7, wherein said match detection means carries out simultaneous comparison with a plurality of types of Huffman tables so that a matched Huffman table is used for continuing the match detection within a predetermined range and if an error is caused in the match detection in said predetermined range, said step of one-bit shift and comparison with a Huffman table is carried out.