Method for distributing video image set bit based on H.264

Abstract

A bit distribution method of groups of video pictures based on H.264 is applied to a video picture encoder which controls the code rate of video stream encoded in real time. The method comprises the following steps: A. the approximation of the quantization parameter mean QPm of a first frame in the video stream GOP is estimated and set as QPi; B. the frame I in the video stream GOP is encoded; C. the present output code rate is calculated; D. according to the code rate calculated in the step C, the QP value of the subsequent frame B or P is adjusted; E. the frame B or P is encoded; F. when the video stream is not over, the step C is executed once again; G. the video stream is over. According to the target code rate and the complexity of the picture contents, the bit distribution method reasonably determines a quantization parameter of the first frame in the groups of video pictures, thus carrying out the bit distribution on the groups of pictures; under the circumstance of one-time encoding, the optimization of the rate distortion can be well realized and the quality of the pictures is relatively stable.

Description

technical field [0001] The present invention relates to coding and decoding technology in the field of video compression, in particular to an H.264-based image group bit allocation method. It is used for rate control of real-time encoded video streams. Background technique [0002] For video real-time communication, due to the limited bandwidth of the communication channel, it is necessary to control the code rate of the video encoding to ensure the smooth transmission of the video code stream and the full utilization of the channel bandwidth. For different application scenarios, there are various rate control strategies in the prior art. The so-called rate control is to dynamically adjust the parameters of the encoder to obtain the target number of bits. It allocates certain bits to a video group of pictures (GOP: Group Of Picture), pictures or sub-pictures in a video sequence. A GOP is a group of images with strong temporal correlation. A GOP usually contains frames in ...

AI Technical Summary

Problems solved by technology

[0011] Therefore, the disadvantage of the above x264 encoder rate control method: the image quality has a significant jump in the first few seconds, that is, the image quality of the first few frames is very poor, and then it improves, which is actually a very fatal weakness

[0012] In order to ensure the continuity and stability of image quality, if all frames of the same GOP are compressed using the same QP, problems will also occur, because the encoding types and image contents between frames are different. If the same QP is used for compression, the size of the compressed code stream will be different, which will inevitably cause the video code rate to be out of control and the image quality to fluctuate more.

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