Dependent Scalar Quantizer Decisions for High-Throughput Entropy Coding
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Solution Overview
Problem
Existing video encoding and decoding technologies face challenges in achieving high throughput and coding efficiency when implementing dependent scalar quantization, particularly due to increased regular coded bins and interleaved bypass coded bins, which degrade performance compared to HEVC and VTM-1 designs.
Innovation Solution
A decision scheme for scalar quantizer selection in dependent scalar quantization that uses SIG-based state transition and context modeling, determining the quantizer based on the significance flag of preceding coefficients, to maintain high throughput and coding efficiency similar to HEVC and VTM-1 designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dependent scalar quantization is implemented with increased regular coded bins and interleaved bypass coded bins, then coding efficiency is improved, but throughput is degraded
Solution Approach 1:
The patent segments the transform coefficient coding process into multiple scan passes, with the first scan pass handling significance flags and the second scan pass handling remaining level information. This segmentation allows different types of data to be processed in separate stages, improving throughput by enabling parallel processing and reducing interdependencies between coding operations.
Solution Approach 2:
The patent performs preliminary action by coding significance flags in the first scan pass before coding the remaining level information in the second scan pass. This preliminary coding of significance information allows the decoder to know in advance which coefficients require further processing, enabling more efficient memory management and reducing the complexity of interleaved bypass coded bins.
2Manufacturing precision
If dependent scalar quantization is implemented, then coding efficiency is improved, but device complexity is increased
Solution Approach 1:
The patent changes the parameter used for quantizer decision from considering multiple previous coefficients to a simplified rule-based approach. The quantizer for the current coefficient is selected based on predetermined rules related to the significance flag of the current coefficient and the quantizer used for the previous coefficient in the scanning order. This parameter change reduces device complexity while maintaining the benefits of dependent scalar quantization.
Solution Approach 2:
Instead of determining the quantizer based on the values of previous coefficients (forward approach), the patent inverts the approach by using significance flags and predetermined rules to determine the quantizer. This inversion simplifies the decision-making process and reduces the computational complexity of the quantizer selection mechanism.
Data Source
AI summary
When dependent scalar quantization is used, the choice of the quantizer depends on the decoding of the preceding transform coefficient, and the entropy decoding of a transform coefficient depends on quantizer choice. To maintain high throughput in hardware implementations for transform coefficient entropy coding, several decision schemes of the scaler quantizer are proposed. In one implementation, the state transition and the context model selection are based on only regular coded bins. For example, the state transition can be based on the sum of the SIG, gt1 and gt2 flags, the exclusive-or function of the SIG, gt1 and gt2 flags, or based on only the gt1 or gt2 flag. When a block of transform coefficients is coded, the regular mode bins can be coded first in one or more scan passes, and the remaining bypass coded bins are grouped together in another one or more scan passes.