Uni-directional Prediction Restriction for B Slice Coding Efficiency

Solution Overview

Problem

Existing video coding technologies face inefficiencies in generating predictive video blocks for bi-directionally inter predicted PUs in B slices, leading to increased complexity and memory bandwidth requirements, especially when the number of small bi-directionally inter predicted PUs increases.

Innovation Solution

Restricting some PUs in B slices to uni-directional inter prediction by generating a merge candidate list and selecting only uni-directional merge candidates, thereby reducing the number of reference blocks used for predictive video block generation, which decreases complexity and memory bandwidth requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If bi-directional inter prediction is used for all PUs in B slices, then prediction accuracy is improved, but device complexity and memory bandwidth requirements increase

Engineering Contradiction:

Improveprediction accuracyVSAvoidcomplexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies different prediction methods to different PUs within the same slice based on their size. Small PUs (8x8 or smaller) use uni-directional inter prediction, while larger PUs use bi-directional inter prediction. This local differentiation optimizes the balance between prediction accuracy and processing complexity for each region.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the prediction process by dividing PUs into different categories based on size thresholds. By segmenting PUs into small (8x8 or smaller) and large (>8x8) categories, the system can apply different prediction strategies to each segment, reducing overall complexity while maintaining accuracy where needed.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If bi-directional inter prediction is used for all PUs in B slices, then prediction accuracy is improved, but memory bandwidth requirements increase

Engineering Contradiction:

Improveprediction accuracyVSAvoidmemory bandwidth

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent applies different prediction methods to different PUs within the same slice based on their size. Small PUs (8x8 or smaller) use uni-directional inter prediction, while larger PUs use bi-directional inter prediction. This local differentiation optimizes the balance between prediction accuracy and processing complexity for each region.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the prediction process by dividing PUs into different categories based on size thresholds. By segmenting PUs into small (8x8 or smaller) and large (>8x8) categories, the system can apply different prediction strategies to each segment, reducing overall complexity while maintaining accuracy where needed.

Inventive Principle:

Principle #1Segmentation

3Device complexity

If uni-directional inter prediction is restricted to small PUs only, then device complexity is reduced, but prediction accuracy deteriorates

Engineering Contradiction:

ImprovecomplexityVSAvoidprediction accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies different prediction methods to different PUs within the same slice based on their size. Small PUs (8x8 or smaller) use uni-directional inter prediction, while larger PUs use bi-directional inter prediction. This local differentiation optimizes the balance between prediction accuracy and processing complexity for each region.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the prediction process by dividing PUs into different categories based on size thresholds. By segmenting PUs into small (8x8 or smaller) and large (>8x8) categories, the system can apply different prediction strategies to each segment, reducing overall complexity while maintaining accuracy where needed.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9426463B2Restriction of prediction units in B slices to uni-directional inter prediction

Publication Date: 2016.08.23 QUALCOMM INC

AI summary

A video coding device generates a motion vector (MV) candidate list for a prediction unit (PU) of a coding unit (CU) that is partitioned into four equally-sized PUs. The video coding device converts a bi-directional MV candidate in the MV candidate list into a uni-directional MV candidate. In addition, the video coding device determines a selected MV candidate in the merge candidate list and generates a predictive video block for the PU based at least in part on one or more reference blocks indicated by motion information specified by the selected MV candidate.