Video Coding Subpictures and Tiles With Adaptive Chroma QP Tables
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Solution Overview
Problem
Current video coding standards face challenges in efficiently processing and decoding video data due to limitations in quantization parameter control, chroma QP table management, and subpicture-related syntax elements.
Innovation Solution
The proposed solution involves refining the management of initial quantization parameters, chroma QP tables, and subpicture-related syntax elements within the video coding framework. This includes signaling initial QP values in multiple layers, allowing different chroma QP tables for various picture types, and optimizing subpicture-related syntax element inclusion or omission based on specific conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple chroma QP tables are used for different picture types, then chroma coding precision is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by allowing different chroma QP tables to be used for different picture types (inter pictures vs. intra pictures). The decoder selectively applies appropriate QP tables based on the picture type, enabling optimized chroma coding precision for each type without requiring all tables to be simultaneously active, thus balancing precision improvement with complexity management.
Solution Approach 2:
The patent implements dynamics by making the chroma QP table selection adaptive based on picture type. The syntax element sps_subeqtableinter_chroma_qp_table_flag dynamically controls whether separate chroma QP tables are used for inter pictures, allowing the system to adapt its complexity level based on the specific coding requirements of each picture type.
2Productivity
If subpicture-related syntax elements are optimized based on conditions, then video coding efficiency is improved, but device complexity increases
Solution Approach 1:
The patent applies dynamics by making syntax element inclusion conditional based on the value of sps_subpic_same_res_flag. When this flag indicates all subpictures have the same resolution, the patent omits redundant syntax elements (sps_subpic_width_minus1 and sps_subpic_height_minus1), reducing complexity. When subpictures have different resolutions, the full syntax set is included to maintain coding efficiency.
Solution Approach 2:
The patent extracts and removes redundant syntax elements from the bitstream when conditions allow. By checking sps_subpic_same_res_flag, the patent selectively omits width and height syntax elements for subpictures when they are redundant, reducing the amount of data that needs to be processed and transmitted while maintaining complete information when needed.
3Measurement precision
If quantization parameter table management is refined with multiple layers, then video decoding performance is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing quantization parameter management into multiple layers: sequence parameter set level (sps) and picture parameter set level (pps). This hierarchical structure allows different QP tables to be defined at different levels, enabling fine-grained control over chroma QP values for different picture types while organizing the complexity in a manageable hierarchical manner.
Solution Approach 2:
The patent adds a new dimension to QP table management by introducing picture-type-specific chroma QP tables (separate tables for inter and intra pictures) in addition to the standard luma QP tables. This creates a multi-dimensional QP management structure that considers both color component (luma/chroma) and picture type (inter/intra), enabling more precise control without requiring a complete redesign of the QP system.
Data Source
AI summary
Embodiments for video encoding and video decoding are described. One example method includes performing a conversion between a video and a bitstream of the video according to a rule, wherein the rule specifies that only one of two conditions is true when a number of subpictures minus 1 indicated by a first syntax element in a sequence parameter set is greater than zero and when a current subpicture with a subpicture index subpicIdx of a first video picture of the video has a second syntax element in the sequence parameter set indicates that a subpicture with the subpicture index subpicIdx of each video picture of the video in a coded layer video sequence is treated as a video picture in a decoding process that excludes an in-loop filtering operation.