Reference Picture Resampling Size Signaling for Adaptive Video Decoding
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Solution Overview
Problem
Existing video coding technologies face challenges in efficiently handling changes in picture size within a coded video sequence, particularly in scenarios where different parts of a scene require different adaptive resolution settings, leading to inefficiencies in reference picture resampling and increased complexity.
Innovation Solution
A method for decoding an encoded video bitstream that determines a resampling ratio based on a flag indicating whether a conformance window is used for reference picture resampling, and if not, uses the output picture size to calculate the resampling ratio, allowing flexible and efficient resampling of reference pictures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If reference picture resampling is performed with fixed picture size, then decoding complexity is reduced, but adaptability to different scene resolutions is limited
Solution Approach 1:
The patent implements dynamic picture size adaptation by introducing a conformance window mechanism that allows the decoded picture size to differ from the reference picture size. The conformance window parameters (offsets and dimensions) are dynamically adjusted based on scene requirements, enabling the system to adapt to different resolutions while maintaining a fixed reference picture size for complexity management.
Solution Approach 2:
The patent segments the picture processing into two distinct components: reference pictures maintained at a fixed size for efficient motion compensation, and conformance windows that define the actual output picture size. This segmentation allows independent optimization of each component - reference pictures for complexity reduction and conformance windows for adaptability.
2Adaptability or versatility
If conformance window parameters are signaled in bitstream, then adaptability to different resolutions is improved, but bitstream overhead increases
Solution Approach 1:
The patent changes the parameter representation by deriving conformance window parameters from the relationship between reference picture size and decoded picture size. Instead of signaling absolute conformance window parameters, the system uses size ratios and offset relationships that can be more efficiently encoded and reduce bitstream overhead while maintaining full adaptability.
3Adaptability or versatility
If reference picture size changes within coded video sequence, then adaptability to different scenes is improved, but processing complexity increases
Solution Approach 1:
The patent implements dynamic resolution adaptation through the conformance window mechanism, where the decoded picture size can change within a coded video sequence while reference pictures remain at a fixed size. This dynamic adjustment is controlled by conformance window parameters that are updated based on scene requirements, providing adaptability without the full complexity of changing reference picture sizes.
Data Source
AI summary
A method, device, and computer-readable medium for decoding an encoded video bitstream using at least one processor, including obtaining a flag indicating that a conformance window is not used for reference picture resampling; based on the flag indicating that the conformance window is not used for the reference picture resampling, determining whether a resampling picture size is signaled; based on determining that the resampling picture size is signaled, determining a resampling ratio based on the resampling picture size; based on determining that the resampling picture size is not signaled, determining the resampling ratio based on an output picture size; and performing the reference picture resampling on a current picture using the resampling ratio.