Subpicture Signaling Layout for Scalable VVC Bitstreams
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing designs for signaling of subpictures, tiles, and slices in VVC face issues such as limited subpicture count, redundant syntax elements, and inefficient signaling mechanisms, which hinder efficient video encoding and decoding processes.
Innovation Solution
The proposed solution involves modifying the coding of sps_num_subpics_minus1 to enable more than 256 subpictures per picture, conditioning syntax element signaling based on present flags, and optimizing the signaling of subpicture IDs and lengths in sequence and picture parameter sets to reduce redundancy and improve parsing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of subpictures is limited to 256 per picture using existing signaling mechanisms, then the syntax structure remains simple, but the adaptability and versatility of video coding are reduced
Solution Approach 1:
The patent applies dynamics by making the bitwidth of the subpicture count field variable rather than fixed. The field width is determined based on the actual number of subpictures in the picture, allowing the signaling mechanism to adapt its complexity to the content requirements. This resolves the contradiction by enabling support for more than 256 subpictures when needed while maintaining compact signaling when the subpicture count is low.
Solution Approach 2:
The patent changes the parameter of bitwidth dynamically based on the number of subpictures. Instead of using a fixed 8-bit field that limits subpicture count to 256, the system adjusts the field width to match the actual requirements, thereby expanding adaptability without permanently increasing complexity. This parameter change allows flexible scaling from small to large numbers of subpictures.
2Reliability
If syntax elements are always included in parameter sets, then reliability of information transmission is improved, but loss of information increases due to redundant signaling
Solution Approach 1:
The patent extracts and removes redundant syntax elements from the parameter sets. By analyzing which subpicture signaling elements are actually needed based on the subpicture count and configuration, the system eliminates unnecessary repetitions and conditional elements, thereby reducing bitstream redundancy while maintaining all essential information for reliable decoding.
Solution Approach 2:
The patent applies partial action by conditionally including syntax elements only when necessary. Instead of always transmitting all possible subpicture parameters, the system transmits only the subset of parameters actually required for the current picture configuration, reducing redundancy while ensuring reliability of the transmitted information.
3Measurement precision
If subpicture identifiers are explicitly signaled in every picture header, then measurement precision of subpicture positioning is improved, but loss of time increases due to repeated signaling
Solution Approach 1:
The patent applies preliminary action by signaling subpicture identifiers and configuration information once in the sequence parameter set (SPS) at the beginning, rather than repeating them in every picture header. This preliminary signaling establishes the subpicture framework that can be reused across multiple pictures, maintaining precision while eliminating redundant transmission and reducing parsing time.
Solution Approach 2:
The patent merges the subpicture identifier signaling into the sequence parameter set, combining multiple pieces of subpicture configuration information into a single location. This consolidation eliminates the need for separate signaling in each picture header, thereby maintaining identifier accuracy while significantly reducing the time loss associated with repeated parsing of identical information.
4Device complexity
If conditional signaling based on flags is implemented, then device complexity is reduced by avoiding unnecessary processing, but ease of operation decreases due to conditional logic requirements
Solution Approach 1:
The patent uses dynamic conditional signaling controlled by flags in the parameter sets. The presence or absence of subpicture-related syntax elements is determined by flag values, allowing the decoding process to adaptively skip unnecessary processing steps. This dynamic approach reduces device complexity by avoiding fixed processing of all possible elements while maintaining relatively simple operation through clear flag-based control logic.
Data Source
AI summary
Methods, devices and systems for signaling the use of subpictures in coded video pictures are described. One example method of video processing includes performing a conversion between a video and a bitstream of a video, wherein the bitstream conforms to a format rule, and wherein the format rule specifies that a first syntax element, which indicates whether a picture of the video can be partitioned, is conditionally included in a picture parameter set (PPS) of the bitstream based on values of a second syntax element, which indicates whether identifiers of subpictures are signaled in the PPS, and a third syntax element, which indicates, in the PPS, a number of the subpictures.