Intra Mode Derivation Using LUT-Based Integer Division
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Solution Overview
Problem
Existing video coding methods face challenges in efficiently replacing floating-point division operations with integer operations for decoder-side intra mode derivation, leading to inefficiencies in video decoding processes.
Innovation Solution
Implementing a look-up-table (LUT) to replace floating-point division operations with integer additions and multiplications for decoder-side intra mode derivation (DIMD) and template-based intra mode derivation (TIMD), thereby simplifying the decoding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If floating-point division operations are used for decoder-side intra mode derivation, then parameter derivation accuracy is improved, but computational complexity and decoding time increase
Solution Approach 1:
The patent changes the parameter type from floating-point to integer for the division operation. Specifically, it uses integer division with right bit-shifting (>>2) to replace floating-point division, maintaining sufficient accuracy while dramatically reducing computational complexity and improving decoding speed.
Solution Approach 2:
The patent introduces a look-up table (LUT) that stores pre-computed integer coefficients to replace complex floating-point division operations. This uses simple integer arithmetic and table lookup instead of expensive floating-point units, achieving similar accuracy with much lower computational cost.
2Measurement precision
If floating-point division operations are used for decoder-side intra mode derivation, then parameter derivation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent substitutes the mechanical/floating-point division operation with an equivalent integer-based computational system. It uses integer multiplication combined with right bit-shifting (>>2) to replace floating-point division, eliminating the need for complex floating-point arithmetic units in the decoder.
Solution Approach 2:
The patent introduces a look-up table (LUT) as an intermediary structure that stores pre-computed integer coefficients. This LUT acts as a mediator between the input parameters and the final derived values, replacing the need for complex real-time floating-point division with simple table lookup and integer arithmetic.
3Productivity
If integer operations are used to replace floating-point division, then decoding efficiency is improved, but parameter derivation accuracy may deteriorate
Solution Approach 1:
The patent carefully adjusts the integer parameters to maintain accuracy. It uses multiplication by 4 (<<2) followed by integer division with right-shifting (>>2), which effectively implements division by 4 while maintaining integer arithmetic. This parameter transformation preserves sufficient precision for intra mode derivation.
Solution Approach 2:
The patent uses a look-up table (LUT) that contains pre-computed integer coefficient values copied from precise floating-point calculations. These pre-computed integer values in the LUT capture the essential accuracy characteristics of the original floating-point parameters, allowing integer operations to achieve comparable derivation accuracy.
Data Source
AI summary
Methods, apparatuses, and non-transitory computer-readable storage mediums are provided for video decoding. In one method, a decoder identifies a floating-point division operation to be performed to derive parameters in decoder-side intra mode derivation (DIMD) mode or in template-based intra mode derivation (TIMD) mode; and the decoder obtains the parameters in the DIMD mode or the TIMD mode by replacing the floating-point division operation with integer additions and multiplications based on a look-up-table (LUT).