IntraBC Mode Decoded Picture Buffer Management
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Solution Overview
Problem
In High Efficiency Video Coding (HEVC) systems, particularly when using the Intra Block Copy (IntraBC) mode, managing the decoded picture buffer (DPB) becomes challenging due to the need to store two versions of the current decoded picture, which can exceed the buffer size, leading to issues in allocating space for reference data.
Innovation Solution
The method involves determining whether the IntraBC mode is used for a current picture and adjusting the maximum allowed number of decoded pictures in the DPB accordingly, using a syntax flag or variable to indicate the need for two versions, and emptying existing pictures if the buffer is full, ensuring the total number of decoded pictures does not exceed the allocated space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two versions of current decoded picture are stored in DPB for IntraBC mode, then reference data availability is improved, but decoded picture buffer size is exceeded
Solution Approach 1:
The patent segments the DPB management into two distinct paths: one for standard HEVC mode (storing only filtered version) and one for IntraBC mode (storing both filtered and unfiltered versions). This segmentation allows the system to allocate buffer space dynamically based on the coding mode being used, ensuring that the additional buffer requirement only applies when necessary for IntraBC reference data availability
Solution Approach 2:
The patent implements dynamic buffer management where the maximum number of decoded pictures in DPB is adjusted based on whether IntraBC mode is used. The system dynamically determines the buffer allocation by checking the IntraBC flag and adjusting the DPB size accordingly, allowing flexibility in resource allocation rather than requiring fixed additional buffer space
2Adaptability or versatility
If maximum number of decoded pictures is increased for IntraBC mode, then buffer allocation flexibility is improved, but device complexity increases
Solution Approach 1:
The patent implements self-service buffer management where the decoding system automatically determines whether IntraBC mode is being used and adjusts the DPB configuration accordingly. The system uses syntax flags in the bitstream to automatically trigger the appropriate buffer management mode, eliminating the need for complex external control mechanisms and reducing overall system complexity while maintaining adaptability
Data Source
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AI summary
Method and apparatus of managing a DPB (decoded picture buffer) for a video coding system are disclosed. Whether the IntraBC mode is used for a current picture is determined and a maximum allowed number of decoded pictures in the DPB is allocated based on whether the IntraBC mode is used for the current picture. The current picture is then encoded or decoded using decoded pictures stored in the DPB as reference data. In another method, a maximum number of reordered pictures in the DPB is determined. If certain conditions are true, one or more decoded pictures stored in the DPB will be emptied until none of the conditions is true. One condition corresponds to a number of decoded pictures in the DPB marked as "needed for output" being greater than the maximum number of reordered picture modified according to whether the IntraBC mode is used for the current picture.