Video Decoder Subpicture Layout Inference
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Solution Overview
Problem
Current video coding standards, such as HEVC, face challenges in efficiently specifying and decoding subpicture layout and slice structure, particularly when dealing with multiple subpictures and non-tile based raster scan slices, which can lead to decreased coding efficiency and increased complexity.
Innovation Solution
The proposed method involves a video decoder that infers the position and size of subpictures and slices based on received specifications in the bitstream, allowing for flexible partitioning of pictures into subpictures and slices, and uses specific syntax elements to signal the layout and structure, enabling efficient decoding and encoding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple subpictures and non-tile based raster scan slices are specified explicitly in the bitstream, then the subpicture layout and slice structure can be precisely defined, but the signaling overhead increases and coding efficiency decreases
Solution Approach 1:
The patent extracts and removes redundant signaling information from the bitstream. Specifically, it eliminates the need to explicitly signal the position of the first subpicture (top-left corner) and the size of the last subpicture, as these can be inferred from the picture dimensions and the specifications of other subpictures. This extraction of unnecessary information reduces signaling overhead while maintaining precise layout specification.
Solution Approach 2:
The patent implements a self-service mechanism where the decoder infers missing subpicture layout information automatically without requiring explicit signaling. The position of the first subpicture is inferred from picture boundaries, and the size of the last subpicture is inferred from the remaining picture area after placing other subpictures. This self-inference capability eliminates redundant signaling while preserving precise layout control.
2Reliability
If all subpicture positions and sizes are signaled in the bitstream, then the layout can be accurately reconstructed, but the bitstream complexity and decoding complexity increase
Solution Approach 1:
The patent removes redundant parameters from the bitstream specification. Instead of signaling all subpicture positions and sizes explicitly, it only signals the necessary subset (positions and sizes of intermediate subpictures), and extracts the remaining information through inference mechanisms. This reduces bitstream complexity while maintaining layout reconstruction accuracy.
Solution Approach 2:
The patent inverts the traditional approach by having the decoder actively infer missing information rather than passively receiving all information from the bitstream. Instead of the encoder providing complete layout information, the encoder provides partial information and the decoder completes the layout reconstruction through logical inference, thereby reducing decoding complexity.
3Productivity
If the position of the first subpicture and size of the last subpicture are not specified, then the signaling efficiency improves, but the inference process requires additional computational resources
Solution Approach 1:
The patent uses simple geometric copying and calculation principles to infer subpicture parameters. The position of the first subpicture is copied from the picture boundary definition, and the size of the last subpicture is calculated by subtracting the sum of other subpicture dimensions from the total picture dimensions. These are basic arithmetic operations that require minimal computational resources.
Solution Approach 2:
The patent employs lightweight inference mechanisms that use simple, disposable calculations rather than complex, persistent computational structures. The inference of subpicture parameters uses basic arithmetic operations that are computationally inexpensive and do not require maintaining complex state information, thereby minimizing power consumption while improving signaling efficiency.
Data Source
AI summary
A method for specifying layout of subpictures is provided. A video decoder receives data from a bitstream to be decoded as a current picture of a video. The video decoder parses the bitstream for positions and sizes of multiple subpictures of the current picture. A position of a first subpicture and a size of a last subpicture are skipped during the parsing. The video decoder reconstructs the current picture and the subpictures of the current picture according to the positions and the sizes of the subpictures.