Adaptive Secondary Transform Set Selection for Intra Video Blocks
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Solution Overview
Problem
Existing video coding technologies face challenges in efficiently selecting transform kernels, leading to increased encoding time and signaling overhead, which can degrade video quality and efficiency.
Innovation Solution
Adaptive selection of a subset of secondary transform sets based on coded information, such as intra prediction mode, to improve encoding/decoding accuracy and reduce signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a reduced subset of secondary transform sets is selected based on coded information, then signaling overhead and encoding time are reduced, but transform selection accuracy may be limited
Solution Approach 1:
The patent applies dynamics by making the transform set selection adaptive rather than static. The encoder dynamically selects from different subsets of secondary transform sets based on coded information such as intra prediction mode, allowing the system to adapt to different block characteristics. This dynamic selection process resolves the contradiction by enabling accurate transform selection without requiring evaluation of all available transform sets, thus reducing encoding time while maintaining selection accuracy.
Solution Approach 2:
The patent segments the complete set of secondary transform sets into multiple subsets, where each subset is associated with specific coded information patterns (e.g., different intra prediction modes). This segmentation allows the encoder to quickly identify and select from a relevant subset rather than evaluating all transform sets, thereby reducing encoding time while maintaining accurate transform selection for the given block characteristics.
2Measurement precision
If adaptive selection based on coded information is used, then transform accuracy is improved, but signaling overhead increases
Solution Approach 1:
The patent extracts and utilizes only the necessary coded information (such as intra prediction mode) that is already available in the bitstream to determine the appropriate transform set subset. By extracting this existing information rather than adding new signaling elements, the system achieves accurate adaptive transform selection without increasing signaling overhead, as the selection is based on information already present in the coded data.
3Reliability
If all available secondary transform sets are evaluated, then optimal transform selection is achieved, but encoding complexity increases
Solution Approach 1:
The patent performs preliminary action by pre-organizing secondary transform sets into multiple subsets based on coded information characteristics before the actual encoding process. This preliminary organization allows the encoder to quickly navigate to the relevant subset without evaluating all transform sets, thereby maintaining optimal transform selection for coding quality while significantly reducing encoding complexity during actual operation.
Solution Approach 2:
The patent implements a dynamic selection mechanism that adapts the search space of transform sets based on coded information. Rather than statically evaluating all transform sets or using a fixed reduced set, the system dynamically adjusts which subset to evaluate based on the specific characteristics of each block, achieving optimal coding quality with reduced complexity for each individual encoding decision.
Data Source
AI summary
The various implementations described herein include methods and systems for coding video. In one aspect, a method includes receiving a video bitstream comprising a plurality of blocks that includes a current block. The method also includes determining an intra prediction mode for the current block and selecting a secondary transform set from a plurality of secondary transform sets based on coded information comprising the intra prediction mode of the current block. The method further includes reconstructing the current block by applying a secondary transform from the selected secondary transform set.