Combined Intra Prediction Modes for Video Encoding
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Solution Overview
Problem
Existing video encoding and decoding technologies face limitations in efficiently predicting the borders of curvy objects and textures due to the need for additional parameters and increased syntax costs when using directional prediction modes, which can result in suboptimal compression and decoding performance.
Innovation Solution
The method involves combining intra prediction modes from neighboring video blocks and adding these combinations to the list of most probable modes used during encoding and decoding, allowing for improved prediction without significant additional syntax overhead, specifically by creating hybrid modes that linearly map directional modes over the current block's surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If directional prediction modes are used to predict curvy objects, then prediction accuracy is improved, but syntax costs and parameter requirements increase
Solution Approach 1:
The patent combines multiple intra prediction modes (planar, DC, and directional modes) into a unified combined intra prediction mode. This merging allows the system to achieve high prediction accuracy for curvy objects by integrating the strengths of different modes while using a single syntax element to select the combined mode, thereby avoiding the increased syntax costs that would result from transmitting multiple separate mode parameters.
Solution Approach 2:
The combined intra prediction mode serves multiple functions: it can predict smooth regions (inheriting from planar mode), flat regions (inheriting from DC mode), and curvy objects (inheriting from directional modes). This multi-functionality allows a single prediction mode to handle various object types effectively, improving prediction accuracy without requiring separate parameters for different prediction scenarios.
2Productivity
If multiple intra prediction modes are combined, then prediction efficiency is improved, but encoding complexity increases
Solution Approach 1:
The patent performs preliminary actions by pre-defining multiple intra prediction modes (planar, DC, and various directional modes) with fixed mathematical formulations. During encoding, the system only needs to select and apply the pre-defined combined mode rather than computing multiple separate predictions, which reduces encoding complexity while maintaining the efficiency benefits of combined prediction.
Solution Approach 2:
The patent changes the parameter representation by using a single syntax element to indicate the combined intra prediction mode instead of multiple parameters for separate modes. This parameter consolidation reduces the computational burden during encoding while still enabling the system to achieve high prediction efficiency through the integrated approach of combining multiple prediction strategies.
3Stability of the object's composition
If filtered reference samples are used, then prediction smoothness is improved, but additional parameters must be transmitted
Solution Approach 1:
The patent merges the filtering operation into the combined intra prediction mode itself. Instead of applying filtering as a separate post-processing step that would require additional parameters, the filtering is integrated into the prediction calculation, allowing the system to achieve smooth predictions while using the same syntax elements as the base combined mode.
Solution Approach 2:
The combined intra prediction mode performs self-service by internally handling the smoothing operation through its integrated formulation. The mode automatically adapts to produce smooth predictions for various object types without requiring external filtering parameters, thereby eliminating the need for additional parameter transmission while maintaining prediction smoothness.
Data Source
AI summary
Encoders and decoders of digital video signals use combined intra prediction modes for some images. In at least one embodiment, combined intra prediction modes can result from the intra prediction modes of neighboring blocks. The combined intra prediction mode can be added to a most probable modes list. Various embodiments describe techniques for combining the intra prediction modes, comprising a combination of reference samples and a combination of directions to form a prediction. Another embodiment adds a combination mode to the most probable modes list if the two modes that are combined to form it are directional modes with angle difference less than 90 degrees. Another embodiment uses a linear combination of intra prediction modes and another embodiment performs a linear combination which depends on the distance of a prediction from the left and above blocs.