IntraBC Reference Picture List Construction for HEVC
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Solution Overview
Problem
In the context of High Efficiency Video Coding (HEVC) with Screen Content Coding, the current picture may not always be included in the reference picture list during Intra Picture Block Copy (IntraBC) mode, leading to issues with encoding and decoding of IntraBC blocks.
Innovation Solution
The current picture is treated as a reference picture and included in one or both reference picture lists by ensuring its presence through unfiltered versions and specific flag signaling, allowing it to be inserted in a predefined position within the reference picture list, ensuring its availability for IntraBC mode coding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current picture is not included in the reference picture list, then the maximum number of reference pictures is maintained, but the IntraBC mode cannot function correctly
Solution Approach 1:
The reference picture list is segmented into two separate lists: List 0 containing temporal reference pictures from other pictures, and List 1 containing the current picture as reference for IntraBC mode. This segmentation allows the current picture to be included without exceeding the maximum reference picture count for inter prediction, while still enabling IntraBC functionality.
Solution Approach 2:
A new reference picture list (List 1) is introduced as an intermediary structure to hold the current picture. This mediator list allows the current picture to be accessed for IntraBC mode without conflicting with the maximum reference picture limit in List 0, thus resolving the contradiction between maintaining the limit and enabling IntraBC.
2Ease of operation
If the current picture is included in the reference picture list, then IntraBC mode can function correctly, but the maximum number of reference pictures is exceeded
Solution Approach 1:
The reference picture list is segmented into two separate lists: List 0 containing temporal reference pictures from other pictures, and List 1 containing the current picture as reference for IntraBC mode. This segmentation allows the current picture to be included without exceeding the maximum reference picture count for inter prediction, while still enabling IntraBC functionality.
Solution Approach 2:
Different parts of the reference picture list management are assigned different qualities/functions: List 0 maintains strict adherence to the maximum reference picture limit for inter prediction, while List 1 provides specialized support for IntraBC mode. This local differentiation allows each list to optimize for its specific purpose without compromising the other.
3Ease of operation
If reference picture list modification is used to include the current picture, then IntraBC mode is enabled, but the encoder and decoder complexity increases
Solution Approach 1:
The current picture is preliminarily added to List 1 during the reference picture list construction phase, before actual encoding/decoding operations. This preliminary action ensures that the current picture is readily available for IntraBC mode without requiring complex runtime modifications or checks, thereby reducing overall system complexity.
Solution Approach 2:
Instead of modifying the existing List 0 structure, a separate List 1 is created by copying the necessary reference picture management logic. This copying approach allows independent management of IntraBC reference pictures without affecting the main reference picture list, simplifying the overall management complexity.
Data Source
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AI summary
A method and apparatus of reference picture list construction for video encoding and decoding includes considering a current picture when an Intra Picture Block Copy (IntraBC) mode is allowed. Embodiments of the reference picture list construction process comprise receiving input data of a current slice in the current picture, determining a temporary reference picture list for the current slice, and determining a final reference picture list from the temporary reference picture list. The reference picture list construction process further comprises adjusting the final reference picture list by setting the current picture to a predefined position in the final reference picture list if the IntraBC mode is allowed. An example of the predefined position is the last position. An example of the reference picture list construction only inserts the current picture into the predefined position when reference picture list modification is not used.