Intra Block Copy Transform Coding for Stable Video Compression

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Solution Overview

Problem

Existing video encoding and decoding technologies face challenges in efficiently handling intra prediction and transform coding, particularly in reducing cross-component redundancy and numerical stability issues in determining filter parameters, which affect compression efficiency and computational complexity.

Innovation Solution

The implementation of intra block copy methods, such as intra template matching prediction (TMP) and low-frequency non-separable transforms (LFNST), along with multiple transform selection (MTS), to derive intra prediction information from reference blocks and apply selected transform coding to current blocks, optimizing the encoding and decoding processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If intra block copy methods are used for prediction, then compression efficiency is improved, but determining filter parameters becomes more complex and numerically unstable

Engineering Contradiction:

Improvecompression efficiencyVSAvoidfilter parameter determination complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent uses lightweight, pre-defined filter kernels (3-tap and 5-tap separable filters) instead of complex adaptive filters. These simple filter kernels are applied directly to the reference block after intra block copy prediction, avoiding the need for complex parameter optimization while maintaining compression efficiency.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the approach from determining complex filter parameters to using fixed, pre-defined filter kernels with simple tap structures. The filter selection is based on the prediction mode rather than optimizing parameters, which simplifies the process and improves numerical stability while preserving compression performance.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If complex transform coding is applied to current blocks, then coding precision is improved, but computational complexity increases

Engineering Contradiction:

Improvecoding precisionVSAvoidcomputational complexity

Core Design Contradiction:

Measurement precisionVSPower

Solution Approach 1:

The patent segments the transform coding process by applying different transform types (DST-I, DST-II, DCT-II) to different frequency regions or block types. This segmentation allows high precision where needed while reducing computational complexity in other regions, optimizing the balance between coding precision and computational load.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different transform coding strategies to different parts of the video data based on local characteristics. For example, certain transform types are applied to specific prediction modes or block regions where they provide the best precision-to-complexity ratio, rather than using a single complex transform throughout.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20260019583A1A method, an apparatus and a computer program product for video encoding and decoding

Publication Date: 2026.01.15 NOKIA TECHNOLOGIES OY

AI summary

A method comprising: processing a video frame; determining a reference block for a current block of the video frame; predicting the current block with an intra block copy method; deriving intra prediction information for the current block based on the reference block; selecting a transform coding for the current block based on the intra prediction information; and applying the selected transform coding to the current block.