Clean Random Access Picture Parameter Indication in HEVC
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Solution Overview
Problem
In High-Efficiency Video Coding (HEVC) systems, random access from Clean Random Access (CRA) pictures requires fetching parameter sets from previous access units, which is a burdensome operation, as all preceding pictures are unavailable for use as reference, and there is no indication of whether parameter sets are needed, leading to inefficient decoding processes.
Innovation Solution
The introduction of an indication mechanism, such as a flag or syntax element, within the bitstream for each CRA picture to specify whether parameter sets from previous access units are required for random access, allowing decoders to determine if fetching operations are necessary, thereby optimizing the decoding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If random access is performed from CRA pictures, then more options for random access are provided without lowering coding efficiency, but fetching parameter sets from previous access units becomes necessary which is a burdensome operation
Solution Approach 1:
The patent introduces a syntax element in advance that indicates whether parameter sets from previous access units are needed for random access from a CRA picture. This preliminary information allows decoders to prepare appropriately before performing random access, avoiding the burden of fetching parameter sets when they are not needed, thus resolving the contradiction between providing random access options and maintaining ease of operation
2Reliability
If parameter sets from previous access units are fetched for random access, then decoding can proceed, but computational burden and processing time increase
Solution Approach 1:
The patent implements a feedback mechanism where a syntax element provides information about whether parameter sets from previous access units are required for random access from CRA pictures. This feedback allows decoders to adjust their processing accordingly, avoiding unnecessary fetching operations and reducing processing time while maintaining reliable decoding capability when needed
Data Source
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AI summary
Techniques of this disclosure provide an indication of whether performing random access from a particular access unit in a bitstream requires fetching of parameter sets from previous access units. A clean random access (CRA) picture can be positioned at any point within a coded video sequence and does not clean a decoded picture buffer (DPB) of a video decoder. In order to perform random access decoding from the CRA picture, a video decoder may need to fetch one or more parameter sets included in unavailable access units that precede the CRA picture. The techniques provide an indication, for each CRA picture, that indicates whether parameter sets included in previous access units are needed to perform random access from the picture. When no parameter sets from previous access units are needed for random access from a particular CRA picture, a video decoder may determine to perform random access from that picture.