Symmetry-Based Interpolation Filtering for Video Coding Sub-Pixel Accuracy
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Solution Overview
Problem
Current digital video encoding and decoding techniques face challenges in accurately generating predictive data, particularly during fractional interpolation, which affects compression efficiency and video quality.
Innovation Solution
The implementation of filtering techniques that utilize coefficient symmetry and pixel symmetry to reduce data transmission between encoder and decoder, generating interpolated predictive data for sub-pixel locations, and applying interpolation-like filtering at integer pixel positions to enhance predictive data accuracy and compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If adaptive interpolation filtering with filter coefficients and offsets is implemented, then predictive data accuracy is improved, but device complexity and data transmission overhead increase
Solution Approach 1:
The filter offset is segmented into an integer component and a fractional component. The integer offset is transmitted explicitly in the bitstream, while the fractional offset is transmitted separately with coarser quantization. This segmentation allows the decoder to reconstruct the full-precision filter offset without transmitting all bits explicitly, thereby improving predictive data accuracy while managing device complexity and bitrate.
Solution Approach 2:
The patent applies different quantization levels to different components of the filter offset based on their magnitude and importance. The fractional offset, which provides fine-tuning capability, is quantized with coarser levels when the integer offset is large, as the relative importance of the fractional component decreases. This parameter change strategy maintains accuracy where needed while reducing overall complexity and bitrate.
2Measurement precision
If filter offsets are transmitted for each sub-pixel position, then interpolation precision is improved, but bit rate increases
Solution Approach 1:
The filter offset transmission is segmented into integer and fractional parts. The integer offset, which represents the dominant component, is transmitted explicitly. The fractional offset, representing the fine adjustment, is transmitted separately with reduced precision (coarser quantization). This segmentation maintains interpolation precision by preserving the important integer component while reducing bitrate through efficient encoding of the less critical fractional component.
Solution Approach 2:
The fractional offset is encoded with coarser quantization levels, effectively using a lower-precision representation for this component. This approach sacrifices some precision in the fractional part (which is less critical when integer offsets are large) in exchange for significant bitrate reduction, maintaining overall interpolation quality while reducing data transmission requirements.
Data Source
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AI summary
This disclosure describes filtering techniques applied by an encoder and a decoder during the prediction stage of a video encoding and/or decoding process. The filtering techniques may enhance the accuracy of predictive data used during fractional interpolation, and may improve predictive data of integer blocks of pixels. There are several aspects to this disclosure, including a useful twelve -pixel filter support that may be used for interpolation, techniques that use coefficient symmetry and pixel symmetry to reduce the amount of data needed to be sent between an encoder and a decoder to configure the filter support for interpolation, and techniques for filtering data at integer pixel locations in a manner that is similar to sub-pixel interpolation. Other aspects of this disclosure concern techniques for encoding information in the bitstream to convey the type of filter used, and possibly the filter coefficients used. Predictive coding of filter coefficients is also described.