Quantization Parameter Selection in Display Stream Compression

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Solution Overview

Problem

Existing video compression techniques, such as display stream compression (DSC), face challenges in determining an optimal quantization parameter (QP) that works across different types of content without relying on a specific rate-distortion model, which can be time-consuming and resource-intensive.

Innovation Solution

A method to calculate QP independently of a rate-distortion model by considering the difference between the bit budget for the current block and the number of bits for encoding the previous block, along with adjustments based on buffer fullness and flatness, allowing for efficient QP determination across various content types.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If rate-distortion models are used to determine QP, then picture quality can be optimized, but computational complexity and implementation cost increase

Engineering Contradiction:
Improvepicture quality optimizationVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the essential function of rate-distortion optimization by removing the complex rate-distortion modeling component. Instead of using full rate-distortion models, the invention uses a simplified approach that determines QP based on buffer fullness and basic rate control, achieving acceptable picture quality without the computational burden of complex models.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces expensive, complex rate-distortion models with a simple, lightweight QP determination method that uses easily accessible information (buffer fullness, current block characteristics). This simplified approach is computationally inexpensive and can be implemented in real-time without requiring heavy computational resources.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Productivity

If content-type-specific rate-distortion models are used, then coding efficiency improves, but implementation difficulty and cost increase

Engineering Contradiction:
Improvecoding efficiencyVSAvoidimplementation difficulty
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The patent creates a universal QP determination method that works across different content types without requiring separate rate-distortion models for each content category. The same simple algorithm based on buffer fullness and basic rate control is applied universally, eliminating the need for complex content-type-specific modeling while maintaining acceptable coding efficiency.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent changes the approach from using complex rate-distortion parameters specific to each content type to using simple, universal parameters such as buffer fullness and basic block characteristics. This parameter simplification makes the system easier to implement while maintaining adaptability to different content types through the universal algorithm.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If complex rate-distortion modeling is performed in real-time, then picture quality optimization is achieved, but processing time increases

Engineering Contradiction:
Improvepicture quality optimizationVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary rate control by maintaining a buffer and tracking bit consumption in advance. The QP determination uses pre-computed buffer fullness information and simple rate control metrics, avoiding the need for complex real-time rate-distortion modeling during the actual encoding process, thus reducing processing time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces the mechanical computation of complex rate-distortion models with a simpler information-processing approach that uses buffer fullness and basic rate control metrics. This substitution dramatically reduces computational complexity and processing time while maintaining the essential function of QP optimization.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP3132602B1System and method for selecting quantization parameter (QP) in display stream compression (DSC)
Publication Date: 2021.04.14 QUALCOMM INC
  • EP3132602B1 patent drawingFigure 1A
  • EP3132602B1 patent drawingFigure 1B
  • EP3132602B1 patent drawingFigure 2A

AI summary

An apparatus for coding video data according to certain aspects includes a memory for storing the video data and a processor. The memory includes a buffer. The processor is configured to receive the video data to be coded. The processor is further configured to determine a quantization parameter (QP) of a current block of the video data without considering a type of content of the video data and a rate-distortion model associated with the type of content. The processor is also configured to code the current block in a bitstream using the determined QP.