Video Decoder CU Division via Width-to-Height Ratio Limits
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Solution Overview
Problem
The complexity of calculating rate-distortion costs for various division manners of coding tree units (CTUs) in video encoding increases the computational burden and reduces encoding efficiency, especially when there are many feasible division methods.
Innovation Solution
The proposed method involves obtaining allowed value ranges for the width-to-height ratio of coding units (CUs) from the bitstream, which allows for the exclusion of certain division manners during decoding and reduces the bitstream's occupied bit rates by saving division information, thereby simplifying the encoding process and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the encoder side attempts to perform encoding in multiple feasible division manners according to the rate-distortion optimization algorithm, then the optimal division manner can be selected, but the calculation complexity of the encoder side increases
Solution Approach 1:
The encoder performs rate-distortion optimization and determines the optimal division manner in advance during the encoding process. The calculated division information (indicating how the CTU should be divided into CUs) is then transmitted to the decoder through the bitstream, allowing the decoder to directly use this pre-determined division information without performing complex calculations
Solution Approach 2:
The encoder calculates rate-distortion costs for multiple feasible division manners, compares these costs, and uses this feedback to select the optimal division manner. This feedback mechanism ensures optimal selection while the results are communicated to the decoder to avoid redundant calculations
2Manufacturing precision
If the encoder side selects a target division manner from all possible division manners using rate-distortion optimization, then the best division manner is obtained, but the encoding process becomes time-consuming
Solution Approach 1:
The encoder performs the time-consuming rate-distortion optimization and division manner selection in advance during encoding. The optimal division information is calculated and transmitted to the decoder, which then uses this pre-determined information directly, significantly reducing the decoder's processing time and making the overall process more efficient
3Measurement precision
If the decoder side needs to reconstruct division information for CUs, then accurate reconstruction is achieved, but more bits are occupied in the bitstream
Solution Approach 1:
The patent extracts only the essential division information (indicating how the CTU is divided into CUs) and transmits it through the bitstream. The decoder uses this extracted division information combined with the received bitstream data to reconstruct the CU division, avoiding transmission of redundant information while maintaining accurate reconstruction
Data Source
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AI summary
This application provides an encoding method and apparatus, and a decoding method and apparatus. The decoding method includes: obtaining first information of a coding tree unit CTU in a to-be-decoded picture from a bitstream, where the first information is used to indicate an allowed value range of a width-to-height ratio of a CU obtained by dividing the CTU; obtaining division information of the CTU from the bitstream; dividing the CTU into one or more CUs based on the first information and the division information, where a width-to-height ratio of the one or more CUs falls within the value range indicated by the first information, and the plurality of CUs do not overlap each other; and decoding the one or more CUs to obtain a reconstructed pixel of the one or more CUs. In this application, division of CUs in some shapes can be excluded based on the value range during decoding, so that some division information previously used to indicate division manners for the CUs can be saved in the bitstream, thereby reducing occupied bit rates.