Fractional Chroma Quantization Parameter Offsets in Video Compression
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Solution Overview
Problem
Current video compression techniques face challenges in achieving improved compression ratios with minimal sacrifice in image quality, especially with limited network resources and increasing demands for higher video quality, due to the limitations of integer-based chroma quantization parameters.
Innovation Solution
The implementation of fractional quantization parameter offsets allows for non-integer values in chroma quantization parameters, enabling finer adjustments and improved compression efficiency by using methods such as fractional chroma QP offsets and delta QP for luma components, which are signaled and utilized in the encoding and decoding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If integer-based chroma quantization parameters are used, then the encoding and decoding processes are simple, but the compression efficiency and image quality cannot be sufficiently improved
Solution Approach 1:
The patent changes the quantization parameter from integer-based to fractional-based, allowing for more precise control of chroma quantization. This enables finer adjustments to the quantization step size, improving compression efficiency and image quality by better balancing luma and chroma coding precision without requiring fundamentally different encoding/decoding architectures
2Manufacturing precision
If higher video quality is demanded, then image quality improves, but the bit rate increases and network resources are consumed faster
Solution Approach 1:
By introducing fractional chroma quantization parameters, the patent enables more efficient allocation of bits between luma and chroma components. This allows achieving higher perceived video quality at lower bit rates by optimizing the quantization process to match human visual system characteristics more closely
Solution Approach 2:
The patent applies different quantization precision levels to different color components (luma vs. chroma) and allows region-specific quantization parameter adjustments. This local quality control enables better compression by allocating more precision where the human eye is more sensitive while maintaining acceptable quality elsewhere
3Productivity
If integer quantization parameters are used, then the coding process is computationally efficient, but the compression ratio cannot be sufficiently improved
Solution Approach 1:
The patent transitions from integer to fractional quantization parameters, enabling more precise control over the quantization step size. This increased precision allows for finer tuning of compression levels, achieving better compression ratios while maintaining image quality through more granular adjustment capabilities
Data Source
AI summary
A method of coding includes receiving a bitstream, obtaining a chroma quantization parameter range offset, a luma quantization parameter, quantization parameter offsets, and coefficients; calculating first intermediate chroma quantization parameters using the chroma quantization parameter range offset, the luma quantization parameter, and the quantization parameter offsets; where the first intermediate chroma quantization parameters have non-integer values; determining second intermediate chroma quantization parameters based on the first intermediate chroma quantization parameters, where the second intermediate chroma quantization parameters have non-integer values; calculating final chroma quantization parameters based on the second intermediate chroma quantization parameters and the chroma quantization parameter range offset; calculating a quantization step using the final chroma quantization parameters; quantizing the coefficients using the quantization step to produce quantized coefficients and transforming the quantized coefficients to residual pixels; and combining the residual pixels with prediction pixels to obtain reconstructed pixels.