Common DPB Management for Multi-Layer Video Decoding
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Solution Overview
Problem
Existing video decoders face challenges in managing a common decoded picture buffer (DPB) for multi-layer video data, as existing methods either maintain sub-DPBs for each layer or a common DPB, leading to issues such as premature removal of reference pictures and buffer overflow.
Innovation Solution
A technique that involves performing a picture output and removal process on the DPB by removing only decoded pictures from the first layer before decoding a current picture, and then conducting a picture bumping process across all layers after removing the last decoding unit from the coded picture buffer (CPB), ensuring necessary reference pictures are retained and the buffer is not overloaded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common DPB is used for all layers, then device complexity is reduced, but reference pictures may be prematurely removed
Solution Approach 1:
The patent segments the DPB management into two distinct processes: layer-specific picture output and removal (applied to the current layer only), and cross-layer picture bumping (applied to all layers). This segmentation allows the system to use a common DPB structure while preventing premature removal of reference pictures by ensuring that removal operations respect layer-specific dependencies before performing broader buffer management.
2Reliability
If picture bumping is performed only for the current layer, then layer-specific reference integrity is maintained, but the DPB may become overly full
Solution Approach 1:
The patent divides the picture removal operation into two segmented phases: first, layer-specific removal that maintains reference integrity for the current layer, and second, cross-layer bumping that manages overall DPB capacity. This segmentation resolves the contradiction by ensuring each phase addresses its specific goal without interfering with the other.
Solution Approach 2:
The patent performs layer-specific picture removal as a preliminary action before executing cross-layer picture bumping. This preliminary action ensures that reference picture integrity is established first, creating a safe foundation for subsequent capacity management operations that may affect multiple layers.
3Reliability
If sub-DPBs are maintained for each layer, then reference picture retention is ensured, but device complexity increases
Solution Approach 1:
The patent merges the DPB storage structure across all layers into a single common buffer, eliminating the need for separate sub-DPBs. However, it maintains reliability by implementing layered removal logic that operates on the unified structure, combining the simplicity of a single buffer with the safety of layer-aware management through the two-phase removal process.
Solution Approach 2:
The common DPB structure serves multiple layers simultaneously, providing universal storage capacity for all layer pictures. The layered removal process adds multi-functionality by enabling the same buffer to be managed differently depending on the current layer being decoded, thus providing both simplicity and reliability.
Data Source
AI summary
A video decoder for decoding multi-layer video data can be configured to maintain a decoded picture buffer (DPB) for storing reference pictures for a plurality of layers, wherein the plurality of layers comprise at least a first layer and a second layer; prior to decoding a current picture of an access unit of the first layer, perform a picture output and removal process on the DPB, wherein to perform the picture output and removal process on the DPB, the one or more processors are further configured to remove from the DPB only decoded pictures that belong to the first layer; and after removing a last decoding unit of the current picture from a coded picture buffer (CPB), perform a picture bumping process across all layers of the DPB.