Video Coding Interpolation Filters and Rounding Error Reduction
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Solution Overview
Problem
Conventional video coding techniques face inefficiencies in compression due to fixed interpolation filters and intermediate rounding errors, which affect the accuracy of predictive data interpolation in motion compensation processes.
Innovation Solution
Implementing a system that uses pre-defined interpolation filters to generate multiple interpolated prediction data sets, allowing selection of the best filter for compression and encoding, while eliminating intermediate rounding errors by storing non-rounded half-pixel values for quarter-pixel interpolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fixed interpolation filters are used in conventional video coding, then device complexity is reduced, but compression efficiency deteriorates due to inability to adapt to different video content characteristics
Solution Approach 1:
The patent implements dynamic filter selection where the encoder chooses from multiple pre-defined interpolation filters (e.g., 6-tap, 8-tap, 10-tap filters) based on the specific video content characteristics. This allows the system to adapt to different scenarios such as high-motion vs. low-motion content, achieving better compression efficiency without requiring complex adaptive filter design during encoding
Solution Approach 2:
The patent changes the parameter of interpolation filter type (number of taps, filter coefficients) to optimize compression performance. By pre-defining multiple filters with different characteristics and selecting the appropriate one for each coding unit, the system achieves adaptability while keeping the complexity manageable through pre-computed filter sets
2Manufacturing precision
If intermediate rounding is performed during half-pixel interpolation, then computational complexity is reduced, but manufacturing precision deteriorates due to rounding errors affecting quarter-pixel interpolation accuracy
Solution Approach 1:
The patent performs preliminary rounding of half-pixel values to integers before using them in quarter-pixel interpolation calculations. By preparing rounded values in advance and using them consistently throughout the interpolation process, the system eliminates the propagation of rounding errors while maintaining computational efficiency
Solution Approach 2:
The patent creates copies of interpolated values at different precision levels - keeping both the original high-precision interpolated values and rounded integer versions. These copies are used in different stages of the process: high-precision values for final output and rounded values for subsequent interpolation calculations, thus eliminating error accumulation
Data Source
AI summary
This disclosure describes various interpolation techniques performed by an encoder and a decoder during the motion compensation process of video coding. In one example, an encoder interpolates pixel values of reference video data based on a plurality of different pre-defined interpolation filters. In this example, the decoder receives a syntax element that identifies an interpolation filter, and interpolates pixel values of reference video data based on the interpolation filter identified by the syntax element. In another example, a method of interpolating predictive video data includes generating half-pixel values based on integer pixel values, rounding the half-pixel values to generate half-pixel interpolated values, storing the half-pixel values as non-rounded versions of the half-pixel values, and generating quarter-pixel values based on the non-rounded versions of the half-pixel values and the integer pixel values.