Video Encoder Chroma Sampling Rate Adaptation
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Solution Overview
Problem
Current video encoding technologies face limitations in supporting high chroma resolution formats like YUV 4:4:4, especially in hardware implementations, and previous approaches for enhancing quality through higher bit rates are inefficient and complex, particularly for content with rich color information.
Innovation Solution
A method that selectively encodes high chroma resolution details on a region-by-region basis using decision rules, allowing existing encoders operating on low-resolution formats like YUV 4:2:0 to provide high chroma resolution, by packing and unpacking sample values into multiple coded pictures with different sampling rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If YUV 4:2:0 chroma sampling format is used for encoding/decoding, then bit rate is reduced and compression efficiency is improved, but chroma resolution and color fidelity deteriorate
Solution Approach 1:
The video stream is segmented into multiple sub-sequences, where some sub-sequences are encoded in YUV 4:2:0 format for compression while other sub-sequences are encoded in YUV 4:4:4 format for high chroma resolution. This segmentation allows different parts of the video to use different chroma sampling rates based on their specific requirements.
Solution Approach 2:
Different chroma sampling rates are applied to different regions or types of video content. Content requiring high color fidelity (such as screens with text, graphics, or rich color information) is encoded in YUV 4:4:4 format, while typical natural video content is encoded in YUV 4:2:0 format, optimizing both compression and quality where needed.
2Manufacturing precision
If YUV 4:4:4 chroma sampling format is used for encoding/decoding, then chroma resolution and color fidelity are improved, but device complexity and hardware support requirements increase
Solution Approach 1:
The system dynamically switches between YUV 4:2:0 and YUV 4:4:4 encoding formats based on the content being processed. By detecting content characteristics (such as presence of text, graphics, or rich color information), the encoder adapts the chroma sampling rate in real-time, using the more complex YUV 4:4:4 format only when necessary rather than universally.
3Manufacturing precision
If higher bit rate is used to improve quality, then chroma resolution is improved, but compression efficiency and rate-distortion performance worsen
Solution Approach 1:
The invention changes the chroma sampling rate parameter from the conventional fixed YUV 4:2:0 to a variable parameter that can be set to YUV 4:4:4 when high chroma resolution is needed. This parameter change allows the system to achieve high chroma resolution without universally increasing bit rate, as the higher resolution format is used selectively based on content requirements.
Data Source
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AI summary
Innovations in encoding of video pictures in a high-resolution chroma sampling format (such as YUV 4:4:4) using a video encoder operating on coded pictures in a low-resolution chroma sampling format (such as YUV 4:2:0) are presented. For example, according to a set of decision rules, high chroma resolution details are selectively encoded on a region-by-region basis such that increases in bit rate (due to encoding of sample values for the high chroma resolution details) happen when and where corresponding increases in chroma resolution are likely to improve quality in noticeable ways. In this way, available encoders operating on coded pictures in the low-resolution chroma sampling format can be effectively used to provide high chroma resolution details.