Reference Picture List Constraints for RADL Video Coding
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Solution Overview
Problem
In multi-layer video coding, the constraints on reference picture lists for RADL (Random Access Decodable Leading) pictures and subpictures are not properly set, leading to potential decoding issues due to incorrect referencing of RASL (Random Access Skipped Leading) pictures across layers with different resolutions.
Innovation Solution
The constraints on active entries in reference picture lists are revised to ensure that RADL pictures and subpictures do not reference RASL pictures that precede an IRAP (Intra Random Access Point) or belong to a different layer, with specific flags and syntax elements used to manage mixed NAL unit types and subpicture treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reference picture lists allow flexible referencing across layers with different resolutions, then coding efficiency is improved, but decoding reliability deteriorates due to incorrect referencing of RASL pictures
Solution Approach 1:
The patent applies parameter changes by modifying the reference picture list construction rules based on picture type parameters. Specifically, it changes the behavior of reference picture list 0 and reference picture list 1 depending on whether the current picture is a RADL picture, thereby controlling which reference pictures can be used and preventing incorrect cross-layer referencing while maintaining efficient coding through selective reference usage.
Solution Approach 2:
The patent applies local quality by implementing different reference picture list constraints for different picture types (RADL vs. other picture types). Instead of applying uniform constraints across all pictures, it locally adapts the referencing rules based on the specific picture type, allowing flexible referencing where appropriate (improving coding efficiency) while preventing incorrect referencing in RADL pictures (maintaining decoding reliability).
Data Source
AI summary
Method and apparatus for signaling or parsing constrained active entries in reference picture lists for multi-layer coding are disclosed. For the decoder side, when the current picture is a RADL (Random Access Decodable Leading) picture, reference picture list 0 or reference picture list 1 of the current picture is mandatorily required to contain no active entry corresponding to a RASL (Random Access Skipped Leading) picture with pps_mixed_nalu_types_in_pic_flag equal to 0 or a picture that precedes an associated IRAP (Intra Random Access Point) picture in decoding order, and wherein an active entry in the reference picture list 0 or the reference picture list 1 of the RADL picture can refer to a RASL picture with the pps_mixed_nalu_types_in_pic_flag equal to 1 and a referenced RASL picture either belongs to the same layer or a different layer than a layer containing the current picture which is the RADL picture.