Adaptive Filter Coefficient Encoding for Video Bitrate Reduction
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Solution Overview
Problem
Current video coding standards face a significant coding overhead due to the representation of adaptive filter coefficients, particularly in low-resolution videos, where the overhead can exceed 10% of the total bit rate, mainly because many adaptive filter coefficients are used per frame, leading to increased bit rate requirements.
Innovation Solution
The method involves entropy encoding adaptive filter coefficients by predicting and encoding the prediction error, leveraging the assumption that un-quantised adaptive filter coefficients typically sum to one and exploiting symmetry in filter coefficients to reduce the number of bits required for representation, using techniques such as mirroring and subdividing filter matrices to optimize encoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If many adaptive filter coefficients are used per frame to improve prediction accuracy, then the prediction quality is improved, but the coding overhead increases substantially
Solution Approach 1:
The patent extracts only the essential information from adaptive filter coefficients by representing them in a simplified form (e.g., using a small number of parameters to describe the filter characteristics) rather than transmitting all individual coefficients, thereby reducing coding overhead while maintaining prediction accuracy
Solution Approach 2:
The patent changes the representation parameters of adaptive filter coefficients from individual coefficient values to a compact parameter set that captures the essential filter characteristics, reducing the quantity of data to be transmitted while preserving the predictive functionality
2Measurement precision
If adaptive filter coefficients are provided to the decoder to improve reconstruction quality, then the reconstruction accuracy is improved, but the bit rate increases by more than 10% for low resolution video
Solution Approach 1:
The patent extracts only the necessary information from adaptive filter coefficients for reconstruction purposes, transmitting a compact representation rather than full coefficient data, thereby reducing bit rate overhead while maintaining reconstruction accuracy
Solution Approach 2:
The patent uses a simplified copy or approximation of the adaptive filter coefficients (represented by a small number of parameters) that can be reconstructed at the decoder side, reducing the amount of data to be transmitted while preserving the essential filtering functionality
Data Source
AI summary
A method of encoding a plurality of adaptive filter coefficients (104, 107, 112) into a bitstream (110). The method comprises the steps of entropy encoding (109) the adaptive filter coefficients (104, 107, 112) into the bitstream (110), whereby a prediction (202) for an instance (204) of the adaptive filter coefficients is determined (201) based on at least one of the remaining adaptive filter coefficients (206), a prediction error (205) is determined (203) based on the difference between the instance (204) of the adaptive filter coefficients and the prediction (202), and wherein the step of entropy encoding (109) the plurality of adaptive filter coefficients (104, 107, 112) comprises entropy encoding (109) the prediction error (205) for the instance (204) of the adaptive filter coefficients and entropy encoding (109) the remaining adaptive filter coefficients (206). Further is provided a corresponding method of decoding a bitstream (110) of encoded adaptive filter coefficients into decoded adaptive filter coefficients (116, 118, 120, 123).