Switchable Filter Index for Video Resampling Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing video coding techniques face challenges in efficiently compressing video data while maintaining high quality, particularly when dealing with reference picture resampling across different pixel grids, as conventional filters perform poorly when used for fractional accuracy in such scenarios.
Innovation Solution
The implementation of a system that identifies filter index information for a current block and determines if the reference picture size differs from the current picture size, using a default filter index for sample rate conversion processes instead of the current filter index, thereby improving encoding and decoding efficiency by selecting appropriate filters for interpolation and resampling tasks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional filters are used for reference picture resampling, then the filtering process is simple, but the fractional accuracy in motion prediction deteriorates
Solution Approach 1:
The patent changes the filter parameters (coefficients) based on the resampling context. When reference picture resampling is detected, the system switches to a second set of filter coefficients optimized for resampling operations, whereas conventional filters use a fixed first set of coefficients. This parameter adaptation resolves the contradiction by providing high fractional accuracy when needed while maintaining simple filtering when resampling is not required.
Solution Approach 2:
The filtering system transitions from a static, fixed-filter approach to a dynamic, context-adaptive approach. The filter dynamically selects between different coefficient sets based on whether reference picture resampling is detected, allowing the system to optimize fractional accuracy for motion prediction when resampling occurs while maintaining simplicity in other scenarios.
2Productivity
If different sized reference pictures are used for inter-prediction, then video compression efficiency is improved, but filtering accuracy deteriorates
Solution Approach 1:
The system detects when reference pictures of different sizes are used (indicating resampling) and automatically switches to a second set of filter coefficients designed specifically for resampling operations. This allows the system to maintain high filtering accuracy even when compression efficiency benefits from using differently sized reference pictures.
Solution Approach 2:
The patent introduces an intermediary detection mechanism that identifies when reference picture resampling is occurring. This detection acts as a mediator between the compression efficiency benefit of using different sized pictures and the filtering accuracy requirement, triggering the appropriate filter coefficient selection to maintain accuracy across both scenarios.
3Device complexity
If a fixed filter index is used for all blocks, then processing complexity is reduced, but encoding and decoding results deteriorate
Solution Approach 1:
Instead of using a fixed filter index for all blocks, the system dynamically changes the filter index based on whether reference picture resampling is detected for each block. This allows the system to maintain low processing complexity through simple detection logic while significantly improving encoding and decoding results by applying the appropriate filter coefficients for each block's specific resampling context.
Data Source
AI summary
Techniques are described for video encoding and decoding using reference picture resampling with switchable filters. One example involves obtaining a current picture and a reference picture, identifying filter index information for a current block of the current picture, and determining that a first picture size value of the current picture and a second picture size value of the reference picture are different. Based on the determining that the first picture size value of the current picture and the second picture size value of the reference picture are different, performing a resampling process using a default filter index in place of a current filter index identified by the filter index information. Additional examples can use the current filter index identified by the filter index information in subsequent blocks. In various examples, the current filter index can be derived or signaled.