Gradual Refresh Signaling for Independent Partial-Region Decoding
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Solution Overview
Problem
Existing video coding schemes like HEVC restrict intra prediction and motion vectors within tiles, making it difficult to independently decode specific partial image regions, leading to degraded coding efficiency.
Innovation Solution
A video decoding apparatus configures a partial image region within a picture for intra prediction, inter prediction, and loop filter processing, while handling regions outside the partial image region similarly to outside the picture, and uses signaling mechanisms for gradual refresh in a coded stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If tiles are used to split pictures for parallel coding and decoding, then decoding efficiency is improved, but intra prediction and motion vector are restricted within tiles, making it difficult to independently decode specific partial image regions
Solution Approach 1:
The invention introduces a new segmentation unit called a 'partial image region' that can be independently decoded. This partial image region is a sub-region within a tile that can be selectively decoded without requiring the entire tile or other regions, enabling fine-grained independent decoding while maintaining the benefits of tile-based parallel processing.
Solution Approach 2:
The invention applies different decoding characteristics to different regions. Within a tile, certain partial image regions can be decoded with restricted prediction (intra prediction and motion vector limited to the partial region) while other regions use normal prediction, allowing localized optimization for independent decoding capability without sacrificing overall decoding efficiency.
2Adaptability or versatility
If motion vector direction is restricted on the coding side to enable partial decoding, then independent decoding capability is improved, but coding efficiency is significantly degraded
Solution Approach 1:
The invention introduces a dynamic flag (partial image region flag) that can be set or cleared based on the specific coding situation. When the flag is set, prediction is restricted to enable partial decoding; when cleared, normal prediction is used to maximize coding efficiency. This dynamic control allows the system to adapt between the two modes without being permanently constrained.
Solution Approach 2:
The invention changes the prediction parameters (intra prediction range and motion vector direction) based on the partial image region flag. When the flag is set, prediction parameters are restricted to the partial region; when cleared, full-range prediction is used. This parameter change mechanism enables the system to switch between independent decoding mode and high-efficiency coding mode.
3Adaptability or versatility
If a partial image region is configured for restricted prediction processing, then independent decoding of partial regions is enabled, but device complexity increases
Solution Approach 1:
The partial image region flag serves multiple functions: it indicates whether prediction should be restricted, it defines the scope of intra prediction, and it controls motion vector direction. By using a single flag variable, the system achieves complex prediction control without proportionally increasing device complexity.
Solution Approach 2:
The partial image region flag acts as an intermediary parameter that mediates between the decoding apparatus and the prediction processing units. Instead of complex hardware control logic, the flag serves as a simple control signal that directs the prediction processing to operate in restricted or full mode, simplifying the overall device architecture.
Data Source
AI summary
A method for signaling gradual refresh for encoding a set of pictures performed by an electronic device is provided. The method identifies a first picture in the set of pictures as being associated with a gradual refreshed picture, and stores a network abstraction layer (NAL) unit type in a coded stream associated with the first picture. The NAL unit type identifies a presence of the gradual refreshed picture. The method then stores, in the coded stream, an enable flag to identify a use of the gradual refresh for encoding at least a subset of pictures in the set of pictures.