DPB Picture Output for Coded Video Sequence Random Access
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Solution Overview
Problem
Existing video coding technologies face challenges in managing decoded picture buffers (DPBs) during random access points, leading to potential overflow and disrupting continuous video playback, especially when dealing with limited network bandwidth and memory resources.
Innovation Solution
Implement techniques to empty the decoded picture buffer (DPB) when encountering specific random access point pictures, such as clean random access (CRA) or gradual random access (GRA) pictures, preventing overflow and ensuring continuous playback by outputting prior pictures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If previously-decoded pictures are kept in the decoded picture buffer (DPB) during random access points, then reference picture availability is improved, but DPB overflow risk increases and playback continuity is disrupted
Solution Approach 1:
The patent applies preliminary action by detecting the random access point picture type (CRA, GRA, or GDR) in advance and proactively emptying the DPB before processing subsequent pictures. This prevents DPB overflow from occurring in the first place, rather than reacting to it after it happens. The decoder checks the picture type and clears the buffer preemptively, ensuring continuous playback is maintained.
Solution Approach 2:
The patent implements dynamic buffer management by adapting DPB emptying behavior based on the specific random access point picture type encountered. Different picture types (CRA, GRA, GDR) trigger different emptying strategies, allowing the system to dynamically adjust its operation to match the actual playback requirements and network conditions, rather than using a static buffer management approach.
2Productivity
If DPB is emptied at random access points, then DPB overflow is prevented and playback continuity is improved, but reference picture history is lost
Solution Approach 1:
The patent applies local quality by selectively emptying the DPB based on the specific random access point picture type encountered. Not all random access points trigger the same emptying behavior - CRA, GRA, and GDR pictures have different emptying requirements. This localized, differentiated approach ensures that buffer management is optimized for each specific case rather than applying a blanket emptying policy.
Solution Approach 2:
The patent changes the buffer management parameter (emptying decision) based on the detected picture type parameter. When a CRA, GRA, or GDR picture is detected, the system modifies its operational parameter to empty the DPB, whereas other picture types maintain normal buffer behavior. This parameter-driven approach allows flexible adaptation to different playback scenarios.
3Quantity of substance
If video data is compressed to reduce data size for network transmission, then bandwidth utilization is improved, but compression complexity increases
Solution Approach 1:
The patent applies self-service by implementing automatic DPB management within the decoder that operates autonomously based on picture type detection. The system monitors incoming pictures, identifies random access points, and automatically performs buffer emptying without external intervention or complex external control mechanisms, thereby simplifying the overall system architecture.
Data Source
AI summary
A method of decoding a coded video bitstream is provided. The method includes receiving the coded video bitstream, wherein the coded video bitstream contains a clean random access (CRA) picture and a first flag having a first value; setting a second value of a second flag equal to the first value of the first flag; emptying, by the video decoder, any previously-decoded pictures from a decoded picture buffer (DPB) based on the second flag having the second value; and decoding a current picture after the DPB has been emptied. A corresponding method of encoding is also provided.