HEVC Transform Tree Syntax Negative Index Resolution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The High Efficiency Video Coding (HEVC) standard's baseline transform tree syntax uses a variable (trafoDepth) as an index for flags, leading to potential negative indices and confusion in signaling hierarchically adjacent chroma blocks' non-zero coefficients, which needs to be addressed for efficient encoding and decoding.
Innovation Solution
A method is introduced to determine if a slice is inter-predicted and check for a parameter in the slice header associated with weighted prediction, using it to perform weighted prediction if enabled, and an improved transform tree syntax is implemented to avoid negative indices and clarify transform block splitting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the baseline transform tree syntax uses trafoDepth as an index to signal chroma block coefficients, then the syntax can be compact, but it results in negative indices when trafoDepth is 0 and causes confusion in signaling
Solution Approach 1:
The patent changes the indexing parameter from trafoDepth to trafoType, where trafoType is derived from trafoDepth but ensures non-negative values. Specifically, when trafoDepth equals 0, trafoType is set to 0 instead of -1, eliminating the negative index problem while maintaining the hierarchical structure signaling capability.
2Adaptability or versatility
If the transform tree syntax uses hierarchical depth as an index, then the structure can represent the tree hierarchy, but it creates confusion when the index becomes negative
Solution Approach 1:
The patent introduces trafoType as an intermediary variable between trafoDepth and the actual array indexing. This intermediary transforms the potentially negative trafoDepth values into non-negative trafoType values, maintaining the hierarchical relationship while ensuring clear and unambiguous syntax interpretation.
Data Source
AI summary
A method, apparatus, article of manufacture, and a memory structure for performing transform tree processing in advanced coding schemes is disclosed. Logical statements having two operands that can result in negative flag indexes have been replaced with conditional multiple logical statements with single operands.