Code rate control algorithm based on fullness degree of virtual encoding buffer area

Abstract

The invention provides code rate control algorithm based on the fullness degree of a virtual encoding buffer area, which meets the requirement of target code rate by strictly controlling the scope of the fullness degree of the virtual encoding buffer area on an encoding end, determines a quantization parameter (QP) value according to the fullness degree of a current virtual encoding buffer area and the change of the fullness degree of the virtual encoding buffer area after the last frame is encoded with the fullness degree of the current virtual buffer area, the change of the fullness degree and the quantization step length of the fullness degree as the input, determines the maximum and minimum QP values according to the complicacy mean of absolute difference (MAD) value of the original data or the residual data of an image or an audio frame, and restricts the scope of the QP value through the maximum and minimum QP values. According to the algorithm, a result is better balanced between code rate control convergence and image or audio quality by considering the changes of the actual complicacy of the image and audio data by strictly controlling the scope of the fullness degree of the virtual encoding buffer area on the encoding end.

Description

technical field [0001] The invention belongs to digital audio and video coding technology, and in particular relates to a code rate control algorithm of digital audio and video coding. Background technique [0002] Bit rate control is one of the very important technologies in audio and video coding. Its main task is to effectively control the audio and video encoder to select the quantization step size so that the size of the output bit stream meets the actual bandwidth limit of the transmission channel, and, as much as possible To obtain the optimal decoded image or audio sampling, bit rate control has always been a hot issue in the field of audio and video coding technology research. Any audio and video standard without bit rate control will have limited application. At present, the well-known algorithms mainly include MPEG-2TM -5, MPEG-4VM8, H.263TMN-8 and H.264JVT-F086, JVT-G012, etc. [0003] Generally speaking, we can decompose the rate control algorithm into two step...

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Problems solved by technology

[0004] For MPEG-2 TM-5, MPEG-4 VM8, H.263 TMN-8 and H.264JVT-F086, JVT-G012 and other algorithms due to RDO (Rate distortion Optimization) iterative calculation (bit allocation), its complexity Higher (such as JVT-F086 requires secondary encoding); due to the large prediction error of the rate-distortion model (calculation of quantization parameters) (such as JVT_G012, MPEG-4VM8), the control effect of the target bit rate is not good, and frame skipping must be used to achieve CBR mode; and when the complexity of the residual data (such as MAD: Mean Average Difference) has a large error or cannot be obtained, the target bit rate control effect is poor and the convergence is poor

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