Mixed NAL Unit Signaling for Adaptive Subpicture Decoding

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Solution Overview

Problem

Existing video coding technologies struggle with efficiently handling changes in picture size and resolution within a coded video sequence, particularly in modern standards like VVC, where adaptive resolution changes (ARC) are not adequately addressed, leading to inefficiencies in encoding and decoding processes.

Innovation Solution

The method involves identifying Network Abstraction Layer (NAL) unit types based on flags in mixed NAL units within subpictures, allowing for adaptive resolution changes (ARC) by signaling ARC parameters through various options such as slice headers, tile group headers, or higher-level parameter sets, enabling efficient decoding of subpictures with independent resolution changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If adaptive resolution changes are implemented in VVC, then encoding and decoding flexibility is improved, but system complexity increases due to lack of standardized signaling mechanisms

Engineering Contradiction:

Improveresolution adaptabilityVSAvoidsystem complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The picture is divided into multiple subpictures, each of which can independently apply adaptive resolution changes. This segmentation allows different resolution adjustments in different regions without requiring complex global control mechanisms, thus improving resolution adaptability while managing system complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Existing NAL unit structures and parameter sets in VVC are extended to support adaptive resolution changes. The same signaling infrastructure is made multi-functional by adding ARC-specific parameters to existing structures, avoiding the need for entirely new complex signaling mechanisms.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If multiple NAL unit types are used for different subpictures, then decoding accuracy is improved, but data overhead increases

Engineering Contradiction:

Improvedecoding accuracyVSAvoiddata overhead

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

Multiple subpictures with different NAL unit types are merged into a single NAL unit structure. The first subpicture uses one NAL unit type while subsequent subpictures use a different NAL unit type, but all are contained within the same NAL unit boundary. This merging approach maintains decoding accuracy through proper type differentiation while reducing data overhead by eliminating redundant NAL unit headers.

Inventive Principle:

Principle #5Merging (Combining)

3Manufacturing precision

If reference pictures are resampled for different resolutions, then picture quality is improved, but processing time increases

Engineering Contradiction:

Improvepicture qualityVSAvoidprocessing time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

Reference pictures are resampled in advance and stored in a reference picture buffer before being needed for decoding. This preliminary action allows the decoder to quickly retrieve pre-processed reference pictures at the required resolution without performing time-consuming resampling operations during the actual decoding process, thus maintaining picture quality while reducing processing time.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12470739B2Method for signaling of mixed NAL unit type in coded video stream

Publication Date: 2025.11.11 TENCENT AMERICA LLC

AI summary

A method, computer program, and computer system is provided for coding video data. Video data including one or more subpictures is received. A network abstraction layer (NAL) unit type associated with each of the one or more subpictures is identified based on checking a flag corresponding to mixed NAL units in the one or more subpictures. The video data is decoded based on the identified NAL unit types.