Adaptive B-picture Quantization Control for Video Encoding
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Solution Overview
Problem
Current video compression techniques do not effectively manage bit rate for B-picture types, leading to suboptimal quality and increased visual artifacts, as they often resort to higher quantization step sizes or uniform dead zone ratios.
Innovation Solution
A video encoder selects a non-uniform quantizer with a larger dead zone ratio for B-picture types, applying it to AC coefficients but not DC coefficients, to control bit rate and improve quality without increasing quantization step sizes, thereby reducing visual artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If higher quantization step sizes are used for B-picture types, then bit rate is controlled, but visual artifacts increase and quality deteriorates
Solution Approach 1:
The patent applies different dead zone ratios to different coefficient types (AC vs DC coefficients) within B-pictures. Specifically, a larger dead zone ratio is applied to AC coefficients while maintaining a smaller ratio for DC coefficients, allowing selective compression that preserves important visual information while controlling bit rate.
Solution Approach 2:
The patent changes the dead zone ratio parameter specifically for B-picture AC coefficients to a larger value, distinguishing it from other picture types and coefficient types. This parameter change enables more aggressive compression of less important frequency components while maintaining quality where it matters most.
2Device complexity
If uniform dead zone ratios are used for all picture types, then implementation is simplified, but bit rate management for B-pictures becomes suboptimal
Solution Approach 1:
The patent introduces dynamic selection of quantizer parameters based on picture type. The encoder dynamically chooses different dead zone ratios for B-pictures compared to other picture types, and dynamically applies different ratios to different coefficient types within B-pictures, optimizing bit rate management for each context.
Solution Approach 2:
The patent applies different dead zone ratios to different coefficient types (AC vs DC coefficients) within B-pictures. Specifically, a larger dead zone ratio is applied to AC coefficients while maintaining a smaller ratio for DC coefficients, allowing selective compression that preserves important visual information while controlling bit rate.
3Quantity of substance
If quantization step sizes are increased to control bit rate, then bit rate is reduced, but quality and detail preservation worsen
Solution Approach 1:
The patent applies different dead zone ratios to different coefficient types (AC vs DC coefficients) within B-pictures. Specifically, a larger dead zone ratio is applied to AC coefficients while maintaining a smaller ratio for DC coefficients, allowing selective compression that preserves important visual information while controlling bit rate.
Solution Approach 2:
The patent changes the dead zone ratio parameter specifically for B-picture AC coefficients to a larger value, distinguishing it from other picture types and coefficient types. This parameter change enables more aggressive compression of less important frequency components while maintaining quality where it matters most.
Data Source
AI summary
The present application is directed to techniques and tools for adapting the quantizer as well as the quantization step size used during video encoding. For example, a video encoder uses a non-uniform quantizer (having a relatively large dead zone ratio) for B-picture types, but uses a uniform quantizer for other types of pictures. In many encoding scenarios, this helps the encoder control bit rate for the B-picture types instead of resorting to higher quantization step sizes, which improves overall quality for the B-picture types.