Decoded Picture Buffer Clearing at GDR Video Sequence Start

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Solution Overview

Problem

Existing video coding technologies face challenges in managing decoded picture buffers (DPBs) during video playback, leading to potential overflow and discontinuous playback due to the lack of efficient handling of previously-decoded pictures, especially at random access points.

Innovation Solution

Implementing techniques for emptying the decoded picture buffer (DPB) when encountering specific types of random access point pictures, such as gradual decoding refresh (GDR) pictures, to prevent overflow and ensure continuous playback by setting flags to control the output of prior pictures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If previously-decoded pictures are retained in the decoded picture buffer (DPB), then reference picture availability is improved, but DPB overflow risk increases and playback continuity deteriorates

Engineering Contradiction:

Improvereference picture availabilityVSAvoidDPB overflow

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by proactively emptying the DPB when a random access point picture is detected, before overflow can occur. The decoder monitors picture types and performs preventive clearing of previously-decoded pictures from the DPB, eliminating the harmful accumulation that would lead to overflow and playback disruption.

Inventive Principle:

Principle #10Preliminary action

2Object-affected harmful factors

If the decoded picture buffer (DPB) is emptied at random access points, then DPB overflow is prevented, but reference picture availability deteriorates

Engineering Contradiction:

ImproveDPB overflow preventionVSAvoidreference picture availability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies local quality by differentiating treatment based on picture type and location in the bitstream. Random access point pictures (IDR, CRA, BLA) trigger DPB emptying, while other pictures maintain normal reference picture operations. This localized approach ensures overflow prevention at critical points while preserving reference availability for regular picture decoding.

Inventive Principle:

Principle #3Local quality

3Quantity of substance

If video data is compressed to reduce data size, then bandwidth utilization is improved, but compression complexity increases

Engineering Contradiction:

Improvevideo data sizeVSAvoidcompression complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by modifying the DPB management state based on picture type parameters. When a random access point picture is detected (identified by specific NAL unit types or flags), the decoder changes the DPB fullness parameter to indicate emptying is required. This parameter-based control enables efficient compression while managing complexity through standardized state transitions.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250350755A1Output of Prior Pictures for Pictures Starting a New Coded Video Sequence In Video Coding

Publication Date: 2025.11.13 HUAWEI TECH CO LTD

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 gradual decoding refresh (GDR) 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 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.