4:1:1 Chroma Subsampling for 4K2K HDMI Transmission
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Solution Overview
Problem
Conventional HDMI specifications face challenges in increasing the refresh rate of high-resolution video data, such as 4K2K, without increasing the data transfer quantity due to the large amount of data per frame.
Innovation Solution
The implementation of a video transmission system using a 4:1:1 format for video data, where the first color difference component and second color difference component of one pixel are allocated to two clock cycles of one transmission channel, and the brightness components of four pixels are allocated to two clock cycles of two other channels, allowing for efficient data transmission over existing HDMI infrastructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high resolution video data (4K2K) is transmitted through conventional HDMI interface, then video quality is improved, but refresh rate cannot be increased due to large data transfer quantity
Solution Approach 1:
The patent changes the video data format parameters from conventional 4:4:4 or 4:2:2 chroma subsampling to 4:1:1 chroma subsampling. This parameter change reduces the amount of color difference component data transmitted while maintaining luminance quality, thereby enabling 4K2K video transmission at 60Hz refresh rate without exceeding the HDMI interface's data transfer capacity
Solution Approach 2:
The patent applies partial chroma subsampling (4:1:1) instead of full chroma sampling (4:4:4). By transmitting only one chroma component for every four luma samples, the system reduces the total data quantity to fit within the HDMI interface limitations while still providing acceptable video quality through the human visual system's lower sensitivity to chroma resolution
2Productivity
If data transfer quantity is increased to achieve higher refresh rate, then refresh rate is improved, but transmission speed requirement increases
Solution Approach 1:
The patent changes the chroma subsampling ratio from conventional values to 4:1:1, which fundamentally alters the data compression ratio. This parameter change enables 60Hz refresh rate transmission at the existing HDMI bandwidth without requiring increased transmission speed, as the reduced data quantity from 4:1:1 subsampling fits within the original interface capacity
3Adaptability or versatility
If conventional HDMI specification is used for 4K2K transmission, then compatibility is maintained, but transmission capacity is insufficient for high refresh rate
Solution Approach 1:
The patent uses partial chroma subsampling (4:1:1) that is more aggressive than conventional HDMI chroma sampling. This partial action approach reduces data transfer capacity requirements to fit within existing HDMI bandwidth limits while maintaining compatibility with the HDMI interface hardware and protocol
Solution Approach 2:
The patent modifies the video data format parameters (chroma subsampling ratio) to 4:1:1, which changes the data compression characteristics. This parameter change enables the system to operate within the original HDMI interface capacity while achieving 4K2K@60Hz transmission, thus maintaining compatibility without requiring capacity expansion
Data Source
AI summary
A device includes a transmitter that transmits, via an interface comprising first, second, and third transmission channels, video data having a 4:1:1 format to a display device. 4:1:1 represents a ratio of a sampling frequencies of a brightness component, to a first color difference component, to a second color difference component. The first and second color difference components of one pixel in a first horizontal line of a first frame of the video data are allocated and transmitted within two clock cycles of the first transmission channel. Brightness components of four pixels in the first horizontal line are allocated and transmitted within two clock cycles of the second and third transmission channels. The transmitter transmits the video data for all of the pixels of the first horizontal line, and thereafter, sets pixels in a second horizontal line as a target to be transmitted.