Picture Header NAL Unit Detection in Video Coding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing video coding standards, such as VVC/H.266, face challenges in accurately detecting the first VCL NAL unit within an access unit, especially when the picture header is signaled in the slice header rather than as a separate NAL unit. This leads to inefficiencies in parsing and decoding processes.
Innovation Solution
The proposed solution involves determining the presence of a picture-header (PH) NAL unit in a picture unit (PU) and identifying the first video-coding-layer (VCL) NAL unit accordingly. If a PH NAL unit is present, the first VCL NAL unit is determined to follow it. Otherwise, the PU is assumed to have only one VCL NAL unit, which is considered the first. Additionally, the method checks if this first VCL NAL unit is part of an access unit (AU) by comparing parameter values with the previous picture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the picture header is signaled in the slice header rather than as a separate NAL unit, then the video coding standard can reduce signaling overhead and improve compression efficiency, but the accuracy of detecting the first VCL NAL unit within an access unit deteriorates
Solution Approach 1:
The method performs preliminary determination of the first VCL NAL unit by checking the presence of PH NAL unit and examining slice header parameters before actual decoding. This preliminary identification resolves the ambiguity of which VCL NAL unit is the first when PH is embedded in slice header, enabling accurate detection without increasing signaling overhead.
2Productivity
If the picture header is embedded in the slice header, then the bitstream structure becomes more compact and compression efficiency improves, but the parsing complexity and decoder burden increase
Solution Approach 1:
The slice header structure serves dual purposes: it both signals picture header information and provides the first VCL NAL unit identification through its own parameters (pic_parameter_set_id, slice_type). The slice header essentially identifies itself as containing the first VCL NAL unit by its structural properties, eliminating the need for separate PH NAL unit markers and reducing parser complexity.
3Adaptability or versatility
If multiple VCL NAL units are present in a picture unit without PH NAL unit, then the picture can be divided into multiple slices for parallel processing, but the difficulty of detecting the first VCL NAL unit increases
Solution Approach 1:
Each slice header contains local identification information (pic_parameter_id, slice_type) that uniquely identifies the first VCL NAL unit within that specific slice. This local quality marker allows the decoder to easily identify the first VCL NAL unit in each slice independently, enabling parallel processing while maintaining simple detection logic through local slice header examination.
Data Source
AI summary
The present disclosure provides methods and apparatuses for processing video content. The method can include: determining whether a picture-header (PH) network-abstraction-layer (NAL) unit is present in a picture unit (PU); in response to the PH NAL unit being present in the PU, determining a first video-coding-layer (VCL) NAL unit of the PU to be a first VCL NAL unit following the PH NAL unit, or in response to the PH NAL unit being not present in the PU, determining that the PU has only one VCL NAL unit and the first VCL NAL unit of the PU is the VCL NAL unit in the PU; and determining whether the first VCL NAL unit of the PU is the first VCL NAL unit of an access unit (AU) containing the PU.