Hierarchical Image Coding for Low-Memory High-Frame-Rate Decoding
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Solution Overview
Problem
Conventional image coding and decoding methods face inefficiencies in processing, particularly when attempting to decode high-frame-rate videos using lower-frame-rate decoding capabilities, leading to buffer overflow and increased memory requirements.
Innovation Solution
An image coding method that hierarchically codes pictures into multiple layers, allowing decoding times to be set at equal intervals for lower-layer pictures without referencing higher layers, and an image decoding method that decodes pictures based on these time intervals, reducing memory requirements and enabling efficient decoding even with lower-frame-rate capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional image coding methods are used to decode high-frame-rate videos, then video quality is maintained, but buffer overflow occurs and memory requirements increase
Solution Approach 1:
The patent divides pictures into multiple hierarchical layers (first layer, second layer, third layer, etc.) based on temporal scalability. Each layer contains pictures with different temporal identifiers, allowing the decoding apparatus to process only relevant layers. This segmentation prevents buffer overflow by controlling which pictures are decoded and when, while maintaining decoding efficiency through selective processing of hierarchical layers.
Solution Approach 2:
The patent introduces dynamic decoding time adjustment where decoding times for pictures in different hierarchical layers are set differently. Specifically, decoding times for pictures in the same hierarchical layer are set to equal intervals, while pictures in higher layers have different decoding time characteristics. This dynamic timing control prevents buffer overflow by synchronizing decoding operations with display capabilities, while maintaining overall decoding efficiency.
2Productivity
If pictures reference higher hierarchical layers, then coding efficiency improves, but decoding complexity increases
Solution Approach 1:
The patent inverts the conventional reference direction by restricting pictures to reference only pictures in the same or lower hierarchical layers, never higher layers. This inversion simplifies the decoding process by eliminating the need to access higher layers during decoding, while maintaining coding efficiency through the hierarchical structure that allows lower layers to be decoded independently first.
Solution Approach 2:
The patent performs preliminary coding of pictures in lower hierarchical layers before higher layers. The hierarchical structure is designed so that pictures in lower layers can be decoded and referenced without requiring access to higher layers. This preliminary ordering of coding operations simplifies decoding by ensuring that all referenced pictures are already available in memory when needed.
3Ease of operation
If decoding times are set at equal intervals for all pictures, then decoding simplicity is maintained, but buffer overflow occurs in high-frame-rate scenarios
Solution Approach 1:
The patent applies different decoding time characteristics to different local groups of pictures based on their hierarchical layer. Specifically, pictures in the same hierarchical layer have equal interval decoding times for simplicity, while pictures in higher layers have different decoding time settings to prevent buffer overflow. This local differentiation maintains decoding simplicity for the majority of pictures while preventing buffer overflow in critical high-frame-rate scenarios.
Data Source
AI summary
An image coding method of hierarchically coding a plurality of pictures to generate a bitstream, includes: coding each of the plurality of pictures, which belongs to any one of a plurality of hierarchical layers, with reference to a picture belonging to a hierarchical layer which is same as or lower than a hierarchical layer to which the picture belongs, and without reference to a picture belonging to a hierarchical layer which is higher than the hierarchical layer to which the picture belongs; and generating the bitstream by coding the coded pictures and time information indicating decoding times of the coded pictures. The time information indicates that the decoding times are set at equal intervals for low-layer pictures which are the plurality of pictures other than highest-layer pictures belonging to a highest layer among the plurality of hierarchical layers.