Code rate estimation method and fast mode decision-making method based on code rate estimation

Abstract

The invention discloses a code rate estimation method and a fast mode decision-making method based on code rate estimation. The code rate calculation formula is as follows: Rori = Rhdr + Re, Rhdr is ahead bit code rate, and Re is a TU code rate; the TU code rate calculation comprises the following steps: S1) carrying out code rate estimation through a weighted quantization coefficient sum SQC, and representing as Rsqc; S2) determining position information Zpos based on a CG level; S3) determining a context model inversion parameter Mturn; S4) determining whether to use the last non-zero coefficient position information Ztlp of the TU level; and S5) calculating the final TU code rates: Rzpos = a1Zpos, Rturbn = a2Mturbn and Rtlp = a3Ztlp, substituting Rzpos, Rturbn and Rtlp into a formula Re, and fitting the calculated code rates to obtain coefficients a1, a2 and a3. According to the method, the code rate is estimated quickly and accurately, so that the aims of reducing the video codingburden and saving the coding time can be fulfilled in the range of acceptable performance loss.

Description

Technical field [0001] The invention relates to the field of video coding, in particular to a code rate estimation method and a fast mode decision method based on code rate estimation. Background technique [0002] In the video encoding process, mode decision-making has a huge time consumption. First of all, in the H.265 video codec standard, there are very flexible block divisions, such as coding units (CU) and transformation units (TU) based on quadtrees. As well as the prediction unit (PU), all CU / PU / TU need to undergo rate-distortion optimization to get the optimal division method. As far as the CU is concerned, the size is 64x64, 32x32, 16x16, and the division is based on the code rate ( The overall performance of R) and distortion (D). It describes the coding quality of the video. The code rate needs to traverse each coefficient to obtain the syntax element of the coefficient level, and then it can complete the entropy coding to obtain the code rate. This process is accompa...

AI Technical Summary

Problems solved by technology

[0010] The above code rate estimation technology uses parameters such as the sum of quantized coefficients (SQC), the number of coefficients greater than one (NG1) and the number of non-zero coefficients (NZ) to perform classification fitting after HDQ quantization. The larger the coefficient, the more code rate consumption, so these parameters can intuitively reflect the code rate information, but the disadvantage of this type of method is that the description of the parameters is too rough and does not take into account the correlation between the code rates between the coefficients. Because the code rate of the coefficient is correlated, the code rate of the previous coefficient will have an impact on the code rate of the next coefficient. If it is not considered, it will lead to performance degradation

[0014] The above code rate estimation technology is to obtain the transform coefficients after performing discrete cosine transform (DCT) on the residual coefficients before HDQ, and process and fit the transform coefficients to predict the code rate. This method uses a threshold to imitate HDQ The process, that is, the transformation coefficient judges whether the coefficient is quantized to non-zero through a threshold, and the transformation coefficient is proportional to the quantization coefficient, so the transformation coefficient can also reflect the code rate to a certain extent, but the disadvantage of this technique is that : Because the quantization process is omitted, the use of transform coefficients to describe the bit rate will be more ambiguous, and the context has a tendency to affect the bit rate during the encoding process, while CABAC is encoded based on accurate quantization coefficients, so the use of residual coefficients means Therefore, the correlation between coefficients and coefficient blocks cannot be considered, resulting in serious performance degradation

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