Intra-frame Prediction Mode Selection in Video Encoding
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Solution Overview
Problem
The selection of an optimal intra-frame prediction mode in video encoding is time-consuming due to the need to calculate prediction residuals for all 35 intra-frame prediction modes, which slows down the video encoding process.
Innovation Solution
A method that first determines the optimal intra-frame prediction mode for a downsampled unit and adjacent units, reducing the number of prediction residuals that need to be calculated by selecting candidate modes based on these optimal modes, thereby accelerating the prediction mode selection process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If prediction residuals are calculated for all 35 intra-frame prediction modes, then the optimal intra-frame prediction mode can be accurately selected, but the video encoding speed decreases
Solution Approach 1:
The patent applies preliminary action by performing downsampling on the current block before mode decision, and by using the optimal mode obtained from the downsampled unit as a preliminary result to guide the full-resolution mode selection. This preliminary processing reduces the computational burden of calculating prediction residuals for all 35 modes at full resolution, while still maintaining accurate optimal mode selection.
Solution Approach 2:
The patent segments the mode decision process into two stages: first, mode decision on a downsampled unit with reduced resolution; second, using the obtained optimal mode to guide the full-resolution mode selection. This segmentation allows the system to perform rough mode filtering at lower computational cost, then refine the selection at full resolution, thereby improving encoding speed without sacrificing accuracy.
2Loss of time
If the number of candidate intra-frame prediction modes is reduced, then the encoding time is shortened, but the accuracy of optimal mode selection may be compromised
Solution Approach 1:
The patent uses the optimal mode obtained from the downsampled unit as a preliminary result to guide the full-resolution mode selection. This preliminary mode information is used to determine the search range and candidate modes for the final decision, ensuring that the reduced set of candidate modes still includes the optimal mode while minimizing the number of prediction residual calculations required.
Data Source
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AI summary
Disclosed are a prediction mode selection method, a video encoding device and a storage medium, belonging to the technical field of video encoding. The method comprises: acquiring a first optimal intra-frame prediction mode of a down-sampling unit corresponding to a target prediction unit, wherein the down-sampling unit is obtained, by means of division, after an image frame that the target prediction unit belongs is down-sampled, and the first optimal intra-frame prediction mode is obtained by performing pre-encoding analysis on the down-sampling unit; according to the first optimal intra-frame prediction mode, adding a candidate intra-frame prediction mode to a candidate mode set; according to a second optimal intra-frame prediction mode of an adjacent prediction unit corresponding to the target prediction unit, adding a candidate intra-frame prediction mode to the candidate mode set; and according to a prediction residual and an encoding cost value corresponding to the candidate intra-frame prediction modes in the candidate mode set, determining an optimal intra-frame prediction mode of the current prediction unit. The embodiments of the present application achieve the effect of improving a video encoding speed while reducing the consumed time of intra-frame prediction mode selection.