Rate controlling method for wavelet coding

Abstract

The invention discloses a method for controlling rate of wavelet-encode, including: obtaining the predicted rate of the current image frame which corresponds to the preset quantization step-length. If the predicted rate can not meet the preset condition which consists of bit-value, average bit-value of frame, threshold of frame-skipping and / or rate of encode frame occupied with the buffer zone, the quantitative step-length mentioned above is adjusted to meet the precondition and the preset rate meeting the condition is taken as the target one when the quantitative step-length meets the preset range. The three components of non-zero of the current image frame multiply with the multiplier factor of the corresponding image frame, add the products together, add the number of bits used for encoding of motion vector and encoding stream organizations, the result of the above is taken as the rate forecast of the current image frame.

Description

technical field [0001] The invention relates to the field of code rate control, in particular to a code rate control method of wavelet coding. Background technique [0002] In recent years, with the deepening of wavelet theory research, the application research of wavelet coding is becoming more and more mature. Wavelet coding technology is widely used in the field of image / video compression because of its special performance of eliminating image block effects, and its unique multi-resolution analysis ability and direction selection ability consistent with human vision, and has achieved good results. [0003] Before the image is encoded by wavelet, the image needs to be transformed by wavelet. Wavelet transform is an analysis method between space domain and frequency domain. see figure 1 , is the distribution map of wavelet coefficients after the image has undergone two wavelet transformations. The image undergoes a wavelet transformation to generate four sub-bands LL1, H...

AI Technical Summary

Problems solved by technology

[0007] However, in wavelet coding, because wavelet transform is used to eliminate the spatial redundancy of the image, and motion estimation is used to eliminate the temporal redundancy of the image, the correlation between two adjacent residual frames becomes very small. It is difficult to accurately predict the current image frame bit rate by using the method of counting the coded image frame bit rate, and the target bit rate configured by the current image frame using the inaccurate predicted bit rate is also inaccurate

[0008] The inaccuracy of the target bit rate makes the number of bits used for encoding the current image frame unreasonable

For example, if there are two adjacent image frames, one has a more complex structure and the other has a simpler structure.

The data information contained in the relatively complex image frame is very large, and the target bit rate of the current image frame is determined only by counting the bit rate of the encoded image frame, which will inevitably make the target bit rate too small, resulting in the bit rate used for encoding the current image frame. The smaller the number, the lower the image quality

Correspondingly, the target bit rate configured for a relatively simple image frame must be too large, and the image quality will be correspondingly high, thus causing great fluctuations in the quality of adjacent image frames. Sensitive, excessive fluctuations in image quality can greatly degrade visuals

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