Moving Image Coding Intra Refresh Timing Control
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Solution Overview
Problem
Existing moving image coding techniques face challenges in reducing the variability of code amounts for intra macroblocks, leading to increased buffer sizes and potential delays, while also compromising image quality due to the need for rough quantization and distinguishable intra macroblocks.
Innovation Solution
A moving image coding apparatus that includes a reset-timing determination unit, an activity calculation unit, and an intra MB determination unit, which determines the timing for intra refresh processes and calculates activity values to selectively set macroblocks as intra macroblocks, thereby optimizing coding and reducing code variability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If intra refresh process is performed for all macroblock lines at the same timing, then the intra refresh process is simple to implement, but the code amount varies significantly per frame requiring large buffer size
Solution Approach 1:
The patent divides the frame into multiple macroblock line groups (first group and second group) and performs intra refresh processes on different groups at different timings. This segmentation of the refresh timing across multiple groups reduces peak code amount by distributing intra macroblocks across frames, thereby reducing buffer size requirements while maintaining implementation feasibility.
2Manufacturing precision
If intra macroblocks are scattered in units of macroblocks, then scanning line artifacts are reduced, but the code amount for intra macroblocks increases significantly
Solution Approach 1:
The patent applies different intra refresh strategies to different macroblock line groups. The first macroblock line group undergoes intra refresh at one timing while the second group undergoes intra refresh at a different timing. This local differentiation in refresh timing optimizes the balance between image quality (reducing scanning line artifacts) and code amount control.
3Quantity of substance
If intra macroblocks are quantized roughly to reduce code amount, then code variability is reduced, but image quality deteriorates significantly
Solution Approach 1:
The patent dynamically adjusts the timing of intra refresh processes for different macroblock line groups based on the frame structure and coding requirements. By making the refresh timing flexible and adaptive rather than fixed and uniform, the system can maintain image quality while controlling code variability through optimized intra macroblock distribution across frames.
Data Source
AI summary
Moving images are coded with reduced deterioration in the image quality while variations in the amount of code per frame are being reduced. A moving image coding apparatus includes a remaining picture number obtaining unit, an activity calculation unit, an intra MB determination unit, and a coding unit. The remaining picture number obtaining unit detects the temporal position of the current frame image, and determines the reset timing at which an intra refresh process is reset in a manner that the reset timing differs for each macroblock line (MBL). The activity calculation unit calculates an activity value for each macroblock (MB). The intra MB determination unit determines a MB to be set as an intra MB based on the activity value calculated by the activity calculation unit. The coding unit codes the MB set as an intra MB through an intra coding process.