Bite rate control method and apparatus thereof

Abstract

The invention discloses a bite rate control method and an apparatus thereof. The method comprises the following steps: calculating a complexity deviation between a present macroblock and a video frame that the macroblock is located at; carrying out bit allocation of the present macroblock according to the complexity deviation; and determining a quantization coefficient of the present macroblock according to the bit allocation of the present macroblock. In the prior art, bit allocation of a macroblock is carried out simply by dividing a macroblock number in a video frame of one frame by a bit of the video frame of the frame; compared with the bit allocation of the macroblock in the prior art, the bit allocations of macroblocks in the invention are respectively carried out by evaluating complexity deviations of all macroblocks, so that a complex macroblock can obtain more bits and thus the quality of a video image is good and stable. Moreover, the method for evaluating a complexity deviation of a macroblock is simple and effective, so that operation complexity can be reduced and effectiveness is also ensured.

Description

【Technical field】 [0001] The invention relates to the field of digital image processing, in particular to a code rate control method and device in video compression. 【Background technique】 [0002] Bit rate control technology is one of the key factors affecting the coding efficiency of video encoders. Its main task is to effectively control the video encoder so that the size of its output bit stream meets the actual bandwidth limit of the transmission channel and obtains the optimal output as much as possible. Decode the image. In view of the importance of bit rate control technology, it has always been a hot issue in the field of video coding technology research. At present, the well-known algorithms are mainly formulated by the International Organization for Standardization (ISO), the International Electrotechnical Commission (IEC) and the International Telecommunication Union (ITU). The code rate control algorithm represented by TML5, TMN8 and H.264. [0003] The main f...

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Problems solved by technology

[0004] In the first step of code bit allocation, the macroblock-level code rate control method is usually used, that is, the code bits are allocated in units of frames; and in the second step of calculating quantization parameters, in order to overcome the traditional TML5 and TMN8 code rate control algorithm Insufficient at the macroblock level, there is already a macroblock-level rate control algorithm in the prior art, and it can accurately control the coding bit of a video frame to the expected range, but it usually only simply sets each The expected number of code bits for each macroblock is the same, so the objective coding quality of the video frame can only be improved to a certain extent

It should be realized that the residual texture information is different for each macroblock in a video frame, so if it is assumed that the expected number of code bits for each macroblock is the same, then the macroblock with more residual information will be Give a larger QP, so that the detailed information of this type of macroblock cannot be fully displayed, which will affect the overall quality of the video frame

In addition, each step of the existing macroblock-level rate control algorithm requires a lot of calculations, and even some algorithms are based on an accurate rate-distortion mathematical model (RDO, rate distortion optimization). The large amount of calculation required is the embedding Therefore, it is necessary to reduce the complexity of the macroblock-level rate control algorithm as much as possible, and to flexibly allocate an appropriate number of codes for different types of macroblocks in the video frame. bit

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