Video Encoding Quantization Thresholding
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Solution Overview
Problem
Existing video encoding methods, such as Rate-Distortion Optimized Quantization, are complex and inefficient, leading to higher bitrates for the same image quality.
Innovation Solution
A method that splits digital images into blocks, transforms them into coefficients, organizes these coefficients into sets, and quantizes them by comparing the sum of magnitudes to a threshold dependent on the number of coefficients within a predefined range, setting coefficients to zero if the sum is below the threshold, and using a deadzone parameter that scales with the index of the coefficients for optimized quantization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Rate-Distortion Optimized Quantization algorithm is used, then encoding efficiency is improved, but implementation complexity increases
Solution Approach 1:
The patent divides the transform coefficients into multiple non-overlapping sets and processes each set independently with a simplified quantization rule. This segmentation allows the complex rate-distortion optimization to be replaced by simpler local decisions on each coefficient set, reducing implementation complexity while maintaining encoding efficiency.
Solution Approach 2:
The patent changes the quantization parameter by using a simplified threshold-based approach instead of the complex rate-distortion optimization algorithm. By transforming the quantization decision from a complex optimization problem to a simple parameter comparison (sum of magnitudes vs. threshold), the implementation complexity is significantly reduced while preserving the essential function of optimizing encoding efficiency.
2Device complexity
If traditional quantization methods are used, then encoding complexity is reduced, but bitrate increases for the same quality
Solution Approach 1:
The patent introduces a feedback mechanism where the quantization decision for each coefficient set is based on the sum of magnitudes of coefficients in that set. This feedback loop allows the encoder to adaptively adjust which coefficients are retained or zeroed out, optimizing the bitrate for a given quality level while keeping the complexity low through the simple sum-comparison rule.
Solution Approach 2:
The patent modifies the traditional quantization parameters by using a dynamic threshold that depends on the sum of coefficient magnitudes. This parameter change enables the system to achieve lower bitrates by more aggressively zeroing out coefficients when their combined magnitude is below the threshold, while maintaining quality when coefficients are significant.
3Quantity of substance
If quantization sets more coefficients to zero, then bitrate is reduced, but image quality degrades
Solution Approach 1:
The patent applies different quantization decisions to different local regions (coefficient sets) based on their specific characteristics. By evaluating the sum of magnitudes for each set and making localized zeroing decisions, the patent preserves important local image features while removing less significant details, thus reducing bitrate without excessive quality degradation.
Solution Approach 2:
The patent uses a adaptive threshold parameter that changes based on the sum of coefficient magnitudes. This dynamic parameter adjustment allows the system to be more aggressive in zeroing coefficients when their total magnitude is low (reducing bitrate) while being more conservative when the magnitude is high (preserving quality), thus optimizing the bitrate-quality tradeoff.
Data Source
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AI summary
The present invention concerns a method for encoding a video sequence, comprising the following steps by a processing unit of an encoding device: - splitting a digital image from the video sequence into blocks of values; - for each block: ∘ transforming the values of the block into transform coefficients; ∘ organizing these transform coefficients into several sets of transform coefficients; ∘ quantizing the transform coefficients into quantized coefficients; ∘ encoding the block using the quantized coefficients; - encoding the video sequence based on the encoding of the blocks; wherein the quantizing step further comprises for quantized coefficients corresponding to one set of transform coefficients: ∘ comparing a sum value representing a result of summing magnitudes of the quantized coefficient values with a threshold, the threshold depending on the number of said summed quantized coefficients, said quantized coefficient magnitudes being comprised within a predefined range; and ∘ setting the quantized coefficients to zero if the summing result is below the threshold.