Palette Mode Coding for Luma and Chroma Components
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Solution Overview
Problem
Current video coding technologies face inefficiencies in applying palette mode coding, particularly when dealing with non-square coding units and separate coding of luma and chroma components, as they often require complex prediction and encoding processes that can lead to increased complexity and reduced coding efficiency.
Innovation Solution
The proposed solution involves using a quadtree plus binary tree (QTBT) structure for video coding, where luma and chroma components are jointly or separately partitioned into blocks using a coding unit (CU) structure, with palette mode applied to luma blocks and non-palette mode to chroma blocks, and determining scan directions based on CU shapes to optimize coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If palette mode coding is applied to colour video data with separate luma and chroma components, then coding efficiency is improved, but the complexity of the encoding process increases due to separate CU structures and prediction requirements
Solution Approach 1:
The patent segments the colour video data into separate luma and chroma components, each with their own CU structures. This allows independent optimization of palette mode application for each component, improving coding efficiency while managing complexity through modular processing of Y, U, and V channels separately
Solution Approach 2:
The patent applies different coding modes locally - palette mode can be selectively applied to luma blocks while using non-palette modes for chroma blocks based on local characteristics. This local quality approach optimizes the balance between coding efficiency and complexity by applying complex palette mode only where most beneficial
2Measurement precision
If joint partitioning of luma and chroma components is used with palette mode, then prediction accuracy is improved, but the device complexity increases due to joint CU structure management
Solution Approach 1:
The patent merges the partitioning structures of luma and chroma components by using the same CU structure for both components. This joint partitioning approach improves prediction accuracy by ensuring consistent block boundaries across colour channels, while the merging itself simplifies the overall structure compared to completely independent partitioning
3Adaptability or versatility
If non-square CUs are supported with palette mode coding, then adaptability to various block shapes is improved, but the difficulty of determining scan direction and prediction increases
Solution Approach 1:
The patent explicitly supports non-square CUs with asymmetric dimensions, allowing the coding structure to adapt to various block shapes. The asymmetry in CU dimensions is handled by establishing clear rules for scan direction determination based on the relative width and height comparisons, making the asymmetric shapes manageable through systematic direction selection
Data Source
AI summary
Methods and apparatus for a coding system using palette mode coding for colour video are disclosed. According to method, when the palette mode is enabled, separate coding of luma and chroma components is disabled or if separate coding of luma and chroma components, the palette mode is disabled. According to another method, when the palette mode is enabled for the current image, palette mode coding is only applied to the luma blocks and non-palette mode coding is applied to the chroma blocks. According to yet another method, palette mode coding is applied to the luma blocks using luma palettes if the palette mode is selected for the luma blocks and palette mode coding applying to the chroma blocks using chroma palettes if the palette mode is selected for the chroma blocks. According to yet another method, the scan direction for a non-square CU depends on the shape of the non-square.