Video Coding with Adaptive Chroma Sampling Formats
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Solution Overview
Problem
Current video coding technologies, such as HEVC, face challenges in achieving optimal compression and quality for professional broadcast and digital cinema applications, particularly in managing chroma channels to maintain image quality and compression efficiency.
Innovation Solution
The proposed solution involves a video data compression and decompression apparatus that utilizes a flexible coding unit structure, adaptive prediction and transform units, and specific scanning and entropy encoding techniques to optimize chroma channel processing, allowing for variable block sizes and non-square transform units to align with image features, thereby improving compression efficiency and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 4:2:0 block structure is used to compress chroma channels, then data compression ratio is improved, but image quality deteriorates
Solution Approach 1:
The patent applies different chroma sampling formats (4:2:0, 4:2:2, 4:4:4) to different regions or types of content based on quality requirements. Professional broadcast and digital cinema applications can use 4:2:2 or 4:4:4 for high-quality regions while 4:2:0 suffices for other content, achieving local optimization of both compression and quality.
Solution Approach 2:
The patent enables dynamic switching between different chroma sampling formats based on content characteristics and quality requirements. The system can adaptively select the appropriate chroma format for different video sequences or regions, optimizing the balance between compression efficiency and image quality in real-time.
2Device complexity
If fixed macroblock structure is used, then device complexity is reduced, but compression efficiency deteriorates
Solution Approach 1:
The patent segments the video content into different coding units with varying chroma sampling formats. By dividing the video stream into multiple segments that can use different chroma formats (4:2:0, 4:2:2, 4:4:4), the system achieves better compression efficiency without requiring complex variable-size blocks throughout the entire system.
Solution Approach 2:
The patent creates a universal block structure that can handle multiple chroma sampling formats within the same macroblock framework. This multi-functional approach allows the fixed macroblock structure to support both compressed (4:2:0) and high-quality (4:2:2, 4:4:4) chroma formats, achieving improved compression efficiency without increasing device complexity.
3Productivity
If chroma channels are heavily compressed, then data transmission efficiency is improved, but colour accuracy deteriorates
Solution Approach 1:
The patent changes the chroma sampling parameters (from 4:2:0 to 4:2:2 or 4:4:4) to maintain colour accuracy for professional broadcast and digital cinema applications. By adjusting this key parameter, the system achieves both high data transmission efficiency through compression and preserved colour accuracy through appropriate sampling format selection.
Data Source
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AI summary
A video coding or decoding method using inter-image prediction to encode input video data in which each chrominance component has 1/Mth of the horizontal resolution of the luminance component and 1/Nth of the vertical resolution of the luminance component, where M and N are integers equal to 1 or more, comprises: storing one or more images preceding a current image; interpolating a higher resolution version of prediction units of the stored images so that the luminance component of an interpolated prediction unit has a horizontal resolution P times that of the corresponding portion of the stored image and a vertical resolution Q times that of the corresponding portion of the stored image, where P and Q are integers greater than 1; detecting inter-image motion between a current image and the one or more interpolated stored images so as to generate motion vectors between a prediction unit of the current image and areas of the one or more preceding images; and generating a motion compensated prediction of the prediction unit of the current image with respect to an area of an interpolated stored image pointed to by a respective motion vector; in which the interpolating step comprises: applying a xR horizontal and xS vertical interpolation filter to the chrominance components of a stored image to generate an interpolated chrominance prediction unit, where R is equal to (U x M x P) and S is equal to (V x N x Q), U and V being integers equal to 1 or more; and subsampling the interpolated chrominance prediction unit, such that its horizontal resolution is divided by a factor of U and its vertical resolution is divided by a factor of V, thereby resulting in a block of MP x NQ samples.