Adaptive Scan Order Entropy Coding for Transform Coefficients
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Solution Overview
Problem
Existing video encoding and decoding technologies face inefficiencies in compression due to fixed scan orders and dependency on intra-prediction modes, leading to increased bit usage and complexity, particularly when numerous intra-prediction modes are available.
Innovation Solution
Adaptive scan order determination based on information within the current block, such as quantized transform coefficients, to optimize entropy coding, reducing dependency on external block parameters and improving coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed scan orders are used for entropy coding, then device complexity is reduced, but coding efficiency deteriorates due to inability to adapt to coefficient distribution
Solution Approach 1:
The patent implements dynamic scan order selection by determining a second scan order based on the distribution of non-zero coefficients in the first group, allowing the encoding process to adapt to different coefficient patterns rather than using a fixed scan order throughout
Solution Approach 2:
The patent changes the scan order parameter based on the observed coefficient distribution in the first group, selecting from multiple possible scan orders (e.g., zigzag, horizontal, vertical, diagonal) to optimize the encoding of subsequent coefficient groups
2Measurement precision
If dependency on intra-prediction modes is increased, then measurement precision of coefficient distribution is improved, but device complexity increases due to multiple mode dependencies
Solution Approach 1:
The patent extracts the scan order determination from dependency on intra-prediction mode by using only the coefficient values from the first group to determine the scan order for subsequent groups, eliminating the need to track and depend on prediction mode information
Solution Approach 2:
The patent segments the transform coefficients into multiple groups and applies different scan orders to different groups, with the second group's scan order determined independently by the coefficient distribution in the first group rather than by prediction mode
3Productivity
If adaptive scan order is implemented, then coding efficiency is improved by matching scan order to coefficient distribution, but device complexity increases due to additional determination steps
Solution Approach 1:
The patent performs preliminary encoding of the first group of coefficients using a default scan order before determining the optimal scan order for subsequent groups, allowing the system to gather coefficient distribution information early and make informed decisions about future scan orders without delaying the overall encoding process
Data Source
AI summary
An encoded bitstream is stored on a non-transitory computer-readable storage medium. The encoded bitstream is configured for decoding by operations that include decoding a subset of quantized transform coefficients of a quantized transform block using a first scan order; determining, based on the subset of the quantized transform coefficients, a second scan order; decoding, based on the second scan order, remaining quantized transform coefficients of the quantized transform block; obtaining a current block based on the quantized transform coefficients.