Reference Picture Management Using Coding Order Index
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Solution Overview
Problem
Existing video coding systems face challenges in efficiently managing reference pictures due to the large number of reference pictures used, which affects processing efficiency and storage requirements, particularly in standards like HEVC where flexible reference picture management is complex.
Innovation Solution
The method introduces Coding Order Index (COI) and Playing Order Index (POI) to determine reference pictures, allowing for efficient reference picture management by defining reference picture parameters in a Reference Configuration Set (RCS) that can be incorporated into bitstream headers, enabling effective reconstruction and removal of reference pictures from the decoded picture buffer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flexible reference picture management is implemented with multiple reference pictures, then video coding performance is improved, but device complexity and storage requirements increase
Solution Approach 1:
The reference picture buffer is segmented into multiple reference picture lists (List 0 and List 1), allowing independent management and selection of reference pictures from different temporal directions. This segmentation enables flexible reference picture management by organizing references into structured groups that can be selectively accessed, reducing overall system complexity while maintaining coding performance.
Solution Approach 2:
The reference picture management system dynamically adjusts the number and selection of reference pictures based on coding conditions. The encoder can flexibly configure reference picture lists with varying numbers of references (e.g., 1-5 pictures per list) and selectively activate references using flags (used_by_curr_pic_s0_flag, used_by_curr_pic_s1_flag), enabling adaptive reference management that optimizes performance while controlling complexity.
2Productivity
If a large number of reference pictures are stored in the decoded picture buffer, then inter-picture coding efficiency is improved, but storage requirements and processing overhead increase
Solution Approach 1:
The patent extracts only the necessary reference pictures from the decoded picture buffer into reference picture lists, rather than storing all decoded pictures. By selectively extracting references based on their utility for prediction, the system reduces buffer storage requirements while maintaining coding efficiency. Useless pictures are identified and excluded from reference lists, minimizing storage overhead.
Solution Approach 2:
The system discards reference pictures that are no longer useful for prediction by removing them from reference lists when they are no longer needed by current or future pictures. The max_num_ref Pictures parameter controls the maximum number of references to maintain, and references exceeding this limit or marked as useless are discarded, freeing buffer space while preserving essential references for ongoing coding.
3Measurement precision
If reference picture parameters are transmitted in the bitstream for each picture, then decoder accuracy is improved, but bitstream overhead increases
Solution Approach 1:
Instead of transmitting complete reference picture list configurations for every picture, the system transmits only partial information - specifically, the number of references to add (num_ref_to_add) and removal flags (remove_overlapping_ref Pictures_flag). This partial transmission approach provides sufficient information for accurate reconstruction while significantly reducing bitstream overhead compared to full parameter transmission.
Solution Approach 2:
Reference picture list configurations are preliminarily established and transmitted in advance through SPS (Sequence Parameter Set) and PPS (Picture Parameter Set) structures. The max_num_ref Pictures parameter and initial reference picture sets are configured beforehand, allowing subsequent pictures to reference pre-established configurations without transmitting redundant information, thereby reducing bitstream overhead while maintaining decoder accuracy.
Data Source
AI summary
A method and apparatus that determine one or more reference pictures for the current image unit and indicate the reference pictures using information associated with COIs (coding order indexes) of the reference pictures are disclosed. The image unit corresponds to a picture, a slice of the picture, or a region of the picture. Inter-picture encoding or decoding is applied to the input data using the reference pictures. The information associated with the COIs can be incorporated in a slice header or a picture header of a bitstream associated with the video sequence. Furthermore, the COI can be represented by a coded COI using a fixed number of bits, wherein the coded COI is constrained to a range from 0 to MAC_COI-1 and MAX_COI is a positive integer.