Method and system for symbol binarization

• US 20040008769A1
• Filed: 07/10/2002
• Published: 01/15/2004
• Est. Priority Date: 07/10/2002
• Status: Active Grant

• Current Assignee: Broadcom Corporation (Broadcom, Inc.)
• Original Assignee: VideoLocus, Inc. (Broadcom, Inc.)
• Inventors: Winger, Lowell
• Granted Patent: US 6,744,387 B2
• Time in Patent Office: Days
• US Class Current: 375/240.02
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/625 using discrete cosine transform [DCT]
• CPC Class Codes: H04N 19/91 Entropy coding, e.g. variable length coding [VLC] or arithmetic coding

Abstract

The present invention is directed to an improved method for the binarization of data in an MPEG data stream. The invention makes use of unary binarization to create codewords up until an index threshold. Once the threshold has been met, succeeding code symbols have appended to them an exp-Golomb suffix. This hybrid binarization scheme reduces the number of binary codewords to be processed by a Binary Arithmetic Coder (BAC), thus reducing the computation required by the BAC.

Claims

1. A method of binarization, said method comprising the step of determining if a code symbol index value is less than a threshold value, if so then constructing a codeword using a first binarization model;

else constructing a codeword using a second binarization model.

2. The method of claim 1 wherein said first binarization model is a unary binarization.

3. The method of claim 1 wherein said second binarization model is a exp-Golomb model.

4. The method of claim 1 wherein said second binarization model comprises the steps of:

a) forming an initial prefix of 1'"'"'s, equal in number to said threshold value minus one;

b) determining the number of bits, γ

+1 required to represent v−

(N−

2) where γ

=└

log₂ (v−

(N−

2)) ┘

, v is the code symbol index value, and N is the threshold value, and then transforming y into a unary representation to create a result;

c) appending the result of step b) to the result of step a);

d) determining the least significant bits, of v−

(N−

2)−

2γ and

e) appending the result of step d) in its binary representation to the result of step c) to create said codeword.

5. A binarization system, said system comprising means for determining if a code symbol index value is less than a threshold value, if so then utilizing means for constructing a codeword using a first binarization model;

else utilizing means for constructing a codeword using a second binarization model.

6. The system of claim 5 wherein said first binarization model comprises means for unary binarization.

7. The system of claim 5 wherein said second binarization model comprises means for exp-Golomb binarization.

8. The system of claim 5 wherein said second binarization model comprises means for:

a) forming an initial prefix of 1'"'"'s, equal in number to said threshold value minus one;

b) determining the number of bits, γ

+1 required to represent v−

(N−

2) where γ

=└

log₂ (v−

(N−

2)) ┘

, v is the code symbol index value, and N is the threshold value, and then transforming y into a unary representation to create a result;

c) appending the result of step b) to the result of step a);

d) determining the least significant bits, of v−

(N−

2)−

2**γ

; and

e) appending the result of step d) in its binary representation to the result of step c) to create said codeword.

9. A computer readable medium containing instructions for binarization, comprising instructions for determining if a code symbol index value is less than a threshold value, if so then constructing a codeword using a first binarization model;

else constructing a codeword using a second binarization model.

10. The medium of claim 9 wherein said first binarization model is a unary binarization.

11. The medium of claim 9 wherein said second binarization model is a exp-Golomb model.

12. The medium of claim 9 wherein said second binarization model comprises instructions for:

a) forming an initial prefix of 1'"'"'s, equal in number to said threshold value;

b) determining the number of bits, γ

+1, required to represent v−

(N−

2) where γ

=┐

log₂ (v−

(N−

2)) ┘

, v is the code symbol index value, and N is the threshold value, and then transforming y into a unary representation to create a result;

c) appending the result of step b) to the result of step a);

d) determining the least significant bits, of v−

(N−

2)−

2**γ

; and

e) appending the result of step d) in its binary representation to the result of step c) to create said codeword.