Intra Prediction Angle Encoding for Video Compression
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Solution Overview
Problem
In high efficiency video coding (HEVC) and future video coding (FVC), the compression efficiency of prediction mode information indicating the angle of intra prediction is low due to the use of context-adaptive binary arithmetic coding (CABAC), leading to an insufficient reduction in code amount for prediction mode information.
Innovation Solution
A method is introduced where the prediction mode information is encoded using a combination of a first encoding method for flag information and a second encoding method for remaining bit values, utilizing locally decoded pixel values to estimate the angle and generate a bit string, thereby reducing the code amount of prediction mode information by using CABAC for context modeling and bypass mode for fixed probability encoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If context-adaptive binary arithmetic coding (CABAC) is used for encoding prediction mode information, then encoding accuracy is improved, but code amount reduction is insufficient
Solution Approach 1:
The prediction mode information is segmented into two parts: a flag indicating whether the intra prediction angle is equal to or greater than 45 degrees, and the actual intra prediction angle. This segmentation allows different encoding methods to be applied to different parts, optimizing overall compression efficiency while maintaining encoding accuracy.
Solution Approach 2:
Different encoding strategies are applied to different parts of the prediction mode information based on their local characteristics. The flag uses context-adaptive binary arithmetic coding (CABAC) for high accuracy, while the actual angle uses exponential-Golomb coding for better compression, creating a localized optimization approach.
2Ease of operation
If the intra prediction angle is encoded directly, then encoding simplicity is maintained, but compression efficiency is reduced
Solution Approach 1:
Before encoding the actual intra prediction angle, a flag is first generated to indicate whether the angle is equal to or greater than 45 degrees. This preliminary action allows the decoder to anticipate the range of the angle and apply appropriate decoding strategies, improving compression efficiency without significantly complicating the encoding process.
Solution Approach 2:
The encoding approach changes based on the value of the intra prediction angle. By introducing a flag that indicates the angle range (less than 45 degrees or 45 degrees and greater), the system adapts the encoding parameters dynamically, achieving better compression efficiency while maintaining relative encoding simplicity.
Data Source
AI summary
An information processing device includes: a memory; and a processor coupled to the memory and configured to: determine an angle of intra prediction for a block to be encoded in an image included in a video, and encode the block to be encoded using the angle of intra prediction; generate a bit value indicating an estimation result of the angle using a locally decoded pixel value of an encoded pixel adjacent to the block to be encoded; generate a bit string indicating the angle of intra prediction and generate flag information indicating whether a partial bit value of the bit string matches the bit value indicating an estimation result of the angle; and encode the flag information by a first encoding method and encode a remaining bit value of the bit string by a second encoding method.