Dependent Quantization of Transform Coefficients Using Dequantization State
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Solution Overview
Problem
Existing video coding methods using independent scalar quantization often result in less accurate reconstructed transform coefficients, leading to suboptimal decoded video quality due to insufficient consideration of the current state information during quantization.
Innovation Solution
Implement dependent scalar quantization where the set of reconstruction values for transform coefficients depends on the values of preceding coefficients, using a weighted sum to adjust for quantization errors by shifting the quantization indices based on current state information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If independent scalar quantization is used, then the quantization process is simple and fast, but the reconstructed transform coefficients are less accurate leading to suboptimal decoded video quality
Solution Approach 1:
The patent implements dynamic quantization where the quantization process adapts based on the current state. The quantizer uses state information from previous coefficients to dynamically adjust the reconstruction values, transitioning from static independent quantization to dynamic dependent quantization that responds to input conditions
Solution Approach 2:
The patent introduces feedback by using the current state (derived from previous quantized coefficients) to influence the current quantization decision. The state machine maintains memory of previous operations and feeds this information back into the quantization process, creating a closed-loop system that improves accuracy
2Measurement precision
If quantization indices are simply shifted to adjust for quantization errors, then the process is computationally efficient, but accuracy is reduced when multiple quantizers are used
Solution Approach 1:
The patent changes the parameter being used for adjustment from a fixed shift amount to a state-dependent offset. Instead of uniformly shifting all quantization indices by the same amount, the system selects different offset values based on the current state, allowing more precise correction tailored to each quantization context
3Reliability
If more accurate dequantized transform coefficients are achieved through dependent quantization, then decoded video quality improves, but the complexity of the quantization system increases
Solution Approach 1:
The patent segments the quantization process into distinct states and transitions, breaking down the complex dependent quantization into manageable state machine components. Each state represents a specific quantization context, allowing the system to handle complexity through structured segmentation rather than monolithic processing
Data Source
AI summary
An example method of video coding includes receiving a video bitstream that includes a plurality of blocks and a plurality of quantized transform coefficients. The method includes deriving a dequantized transform coefficient for a first quantized transform coefficient of the plurality of quantized transform coefficients. The method also includes obtaining an adjusted transform value and reconstructing a first block using the adjusted transform value. Systems and storage mediums for storing instructions/executing instructions for performing the example method are also disclosed.