H.264 Study Notes 6-exponential Columbus code

In H.264, the use of cabac requires binarization, and the exponential Columbus encoding is a binary processing method of cabac. The specific process of the K-order index Columbus codec is as follows:

A. Encoding Process:Assume that the number to be encoded is codenum (must be a non-negative integer)

[Mzeors] [1] [info] is taken as the index after Columbus encoding, and mzero indicates M 0.

1. Describe codenum in binary format (if less than K bits, add 0 to the Front) and remove the next K bits (if it is exactly K bits, remove K bits and get 0 ), add 1 to the result (value) to obtain the binary number T1;

2. m is the binary digit T1 minus one;

3. Then, connect the rounded K-bit in step 1 to the end of step T1, and get [1] [info].

Set the binary number of [info] to I. The encoding process can also be described as follows:

[1 info] is the binary representation of codenum + 2 ^ K. M = I-k is the number of 0 in mzeros.

The total encoding length is codelen = m + 1 + I = 2 m + k + 1.

B. decoding process:

1. Read 0 consecutive times, and the number of 0 consecutive times is M;

2. Calculate codelen = 2 m + k + 1. The number of digits in [1 info] is I = codelen-M = m + k + 1;

3. Read the I-bit binary code word and convert it into a 10-digit system, which is assumed to be w. From W = codenum + 2 ^ K, codenum = W-2 ^ K.

C. Example:

For k = 0: codenum = 3. The encoding is as follows:

The binary value is 11. If K = 0 is removed, 100 is obtained after 1 is added;

So m = 2;

The encoded result is [mzeros] [1] [info] = [mzeros] [1 info] = 00100.

Decoding is as follows:

Read 2 consecutive 0 s, so m = 2; codelen = 2 m + 1 + k = 5; so you need to read 3 more code streams 100, [1 info] is 100, convert to decimal result W is 4, so codenum = W-2 ^ K = 4-1 = 3;

For k = 0 and codenum = 6, the encoding is 00111;

For k = 3 and codenum = 3, the encoding is 1011;

For k = 3 and codenum = 6, the encoding is 1110;

For k = 3 and codenum = 10, the encoding is 010010;

H.264 Study Notes 6-exponential Columbus code