Reference Picture List Index Inference for Slice Header Bit Savings
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Solution Overview
Problem
Existing video coding technologies face inefficiencies in managing reference picture lists, leading to increased bandwidth usage and reduced compression efficiency, especially in high-quality video streaming and storage scenarios.
Innovation Solution
Implementing a flag (rpl1_idx_present_flag) to determine whether the index to a second reference picture list structure is the same as the first, allowing for inferred indexing and reducing redundant signaling in video bitstreams, which can be included in picture or sequence parameter sets and slice headers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the index to the second reference picture list structure is explicitly signaled in the slice header, then the decoder can accurately identify the reference picture list structure, but the bandwidth usage increases and compression efficiency decreases
Solution Approach 1:
The patent applies the copying principle by allowing the second reference picture list structure to copy the index from the first reference picture list structure when they are identical. Instead of transmitting the index separately for both lists, the decoder copies the index value from the first list structure to the second, eliminating redundant bit transmission while maintaining accurate identification of reference picture list structures
Solution Approach 2:
The patent extracts only the necessary information for reference picture list identification. By using a flag to indicate whether the second list index is present, the system extracts and transmits only the essential data - either just the first list index (when lists are identical) or both indices (when they differ) - thereby reducing unnecessary bandwidth consumption
2Loss of information
If redundant indexing information is transmitted for both reference picture list structures, then complete reference information is available, but the bitstream size increases and compression ratio deteriorates
Solution Approach 1:
The patent implements partial action by conditionally transmitting index information. Instead of always transmitting both reference picture list indices, the system transmits only what is necessary - the first list index always, and the second list index only when it differs from the first. This partial transmission approach maintains complete reference information while minimizing bitstream size
Solution Approach 2:
The patent merges the indexing information for both reference picture list structures into a unified signaling mechanism. By using a single flag (rpl1_idx_present_flag) to control the presence of the second list index and allowing inference from the first list index, the system combines what would otherwise be separate transmission requirements into one efficient signaling approach, reducing overall bitstream volume
3Loss of energy
If a flag is introduced to indicate presence of the second reference picture list index, then bandwidth is reduced through inferred indexing, but the device complexity increases due to additional flag parsing logic
Solution Approach 1:
The patent applies self-service by enabling the decoder to automatically infer the second reference picture list index from the first list index when the flag indicates absence. The decoding logic serves itself by using already-decoded information (the first list index) to derive the second index without requiring additional transmission, thereby reducing bandwidth while the added complexity remains manageable through this self-referential approach
Data Source
AI summary
A method of decoding a coded video bitstream is provided. The method includes parsing a flag; parsing a first reference picture list structure; determining that an index to a second reference picture list structure is not present in a slice header of the coded video bitstream and inferring that the index to the second reference picture list structure is the same as an index to the first reference picture list structure when the flag has a first value; determining that the index to the second reference picture list structure is present in the slice header when the flag has a second value; generating a reference picture list using the first reference picture list structure or the second reference picture list structure; and performing inter-prediction based on the reference picture list to generate a reconstructed block.