Lossless Video Coding with Split Residual Blocks for Large CUs

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Solution Overview

Problem

Existing video coding standards like VVC face challenges in efficiently handling lossless coding modes, particularly with residual blocks larger than 32x32, leading to inefficiencies and potential codec implementation issues.

Innovation Solution

Propose methods to align the maximum residual coding block size for lossless CUs with the maximum block size supported by transform skip mode, and selectively choose residual coding schemes for lossless CUs, avoiding unnecessary application of decoder-side tools like BDOF and DMVR.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the maximum residual coding block size for lossless CUs is increased beyond 32x32, then the coding efficiency is improved, but the codec implementation becomes problematic and computational complexity increases

Engineering Contradiction:

Improvecoding efficiencyVSAvoidcodec implementation complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent divides large residual blocks (greater than 32x32) into multiple smaller sub-blocks of 32x32 or smaller. This segmentation allows the residual coding to be performed on manageable block sizes that are compatible with existing codec implementations, while still achieving efficient compression through proper handling of the partitioned blocks in lossless mode.

Inventive Principle:

Principle #1Segmentation

2Productivity

If decoder-side tools like BDOF and DMVR are applied to lossless CUs, then the coding efficiency is improved, but the computational complexity increases

Engineering Contradiction:

Improvecoding efficiencyVSAvoidcomputational complexity

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent applies different processing qualities to different coding modes. For lossless CUs, decoder-side tools like BDOF and DMVR are selectively avoided or applied with reduced intensity, recognizing that lossless coding already achieves perfect reconstruction without needing additional refinement tools. This local differentiation optimizes computational resources by avoiding redundant processing in modes where it provides minimal benefit.

Inventive Principle:

Principle #3Local quality

3Productivity

If the residual coding block size is aligned with transform skip mode maximum block size, then the coding efficiency is improved, but the flexibility in handling various block sizes is reduced

Engineering Contradiction:

Improvecoding efficiencyVSAvoidblock size flexibility

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent introduces dynamic block size handling where the residual coding block size can adapt between different modes. When operating in lossless mode with large blocks, the system dynamically partitions them into 32x32 sub-blocks. When operating in transform skip mode or other modes, the full flexibility of various block sizes is maintained. This dynamic approach allows the system to optimize for coding efficiency in specific modes while preserving versatility across different operating conditions.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12477121B2Lossless coding modes for video coding

Publication Date: 2025.11.18 BEIJING DAJIA INTERNET INFORMATION TECH CO LTD

AI summary

Methods and apparatuses are provided for video coding with lossless coding modes. The method includes: partitioning a video picture into a plurality of CUs comprising a lossless CU; determining a residual coding block size of the lossless CU; and in response to determining that the residual coding block size of the lossless CU is greater than a predefined maximum value, splitting the residual coding block into two or more residual blocks for residual coding.