Reference Picture Selection After Intra Frames for Error-Resilient Decoding
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Solution Overview
Problem
Conventional moving picture coding and decoding methods face challenges in correctly decoding pictures following an intra coded picture, especially when stream errors occur, as they rely on previous pictures for reference, leading to potential decoding failures.
Innovation Solution
The method determines an intra coded picture as an anchor and restricts reference pictures to only those coded after it, ensuring that decoding can start from any intra coded picture and maintain accuracy even with stream errors by using a moving picture coding and decoding apparatus that selects appropriate reference pictures from memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional moving picture decoding methods use previous pictures as reference for decoding current pictures, then decoding efficiency is improved, but decoding reliability deteriorates when stream errors occur
Solution Approach 1:
The patent segments the reference picture set into two distinct parts: (1) pictures decoded before the current picture in display order, and (2) pictures decoded after the current picture in display order. This segmentation allows the decoder to selectively use only the second part as reference pictures, preventing error propagation from the first part while maintaining efficient inter-picture decoding. The segmentation resolves the contradiction by enabling reliable decoding (using only error-free future pictures) without sacrificing decoding efficiency (still using multiple reference pictures).
2Quantity of substance
If the decoder uses any available previous pictures as reference, then the number of reference pictures increases improving compression, but error propagation risk increases
Solution Approach 1:
The patent extracts and removes the harmful component (pictures decoded before the current picture in display order) from the reference picture set. By taking out only the error-prone pictures and retaining only the safe reference pictures (those decoded after the current picture in display order), the system maintains a sufficient number of reference pictures for good compression while eliminating the source of error propagation. This extraction principle directly resolves the contradiction between having many reference pictures and avoiding error propagation.
3Adaptability or versatility
If the system allows reference to any coded picture for maximum flexibility, then coding versatility is improved, but decoding accuracy deteriorates when stream errors occur
Solution Approach 1:
The patent applies preliminary action by pre-establishing a constrained reference picture selection rule before decoding occurs: only pictures decoded after the current picture in display order may be used as references. This preliminary constraint prevents the decoder from accidentally using error-corrupted pictures as references, thereby maintaining high decoding accuracy. At the same time, the system retains coding versatility by still allowing multiple future pictures to be used as references, just with a predetermined directional constraint that ensures accuracy.
Data Source
AI summary
A moving picture coding apparatus 1 includes a counter unit 102 which counts the number of pictures following an intra coded picture; and a motion estimation unit 101 which compares respectively only reference pictures which are the intra coded picture or the following pictures, selected from among a reference picture Ref1, a reference picture Ref2 and a reference picture Ref3 stored in memories 408˜410, with a picture signal Vin, and determines the reference picture whose inter picture differential value is smallest.