Intra Prediction Transform Switching for Lower Video Encoding Load
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing two-step frequency transform in video coding, such as in Joint Exploration Test Model (JEM) software, requires improvement in processing amount for blocks to which intra prediction is applied.
Innovation Solution
Implementing a two-step frequency transform using explicit multiple core transform (EMT) as the primary transform and non-separable secondary transform (NSST) with adaptive selection of transform bases, and adjusting transform processes based on intra prediction modes and block characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a second transform is performed on first transform coefficients using a second transform basis, then compression efficiency is improved, but processing load increases significantly
Solution Approach 1:
The patent changes the parameter of transform basis selection by comparing the first transform basis with a predetermined transform basis. Based on this comparison, the system dynamically adjusts whether to perform the second transform, thereby optimizing the balance between compression efficiency and processing load through parameter-based decision making
Solution Approach 2:
The patent introduces dynamic adaptability by making the second transform optional rather than fixed. The system dynamically determines whether to apply the second transform based on the relationship between transform bases, allowing flexible adjustment of processing complexity while maintaining compression performance when needed
2Loss of energy
If transform bases and parameters are optimized to improve compression efficiency, then compression efficiency improves, but device complexity increases
Solution Approach 1:
The patent simplifies device complexity by changing the parameter selection strategy. Instead of optimizing multiple transform bases and parameters independently, the system uses a predetermined transform basis as a reference point, reducing the search space and computational complexity while maintaining compression efficiency
Solution Approach 2:
The patent employs a predetermined transform basis that serves as a reusable reference, eliminating the need for complex real-time optimization of transform parameters. This approach uses a fixed, simple reference structure that reduces device complexity while still enabling effective compression when the second transform is applied
Data Source
AI summary
An encoder that encodes a current block in a picture includes circuitry and memory. Using the memory, the circuitry: determines whether to use intra prediction for the current block; and when determining to use intra prediction, (i) performs a first transform on a residual signal of the current block using a first transform basis to generate first transform coefficients; and (ii-1) performs a second transform on the first transform coefficients using a second transform basis to generate second transform coefficients and quantizes the second transform coefficients, when an intra prediction mode of the current block is a predetermined mode or when the first transform basis is same as a predetermined transform basis; and (ii-2) quantizes the first transform coefficients without performing the second transform when the intra prediction mode is different from the predetermined mode and the first transform basis is different from the predetermined transform basis.