Hierarchical Video Coding Mode Control via Multi-Level Flags
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Solution Overview
Problem
Current video coding standards, such as HEVC and VVC, face challenges in efficiently controlling coding modes to optimize compression performance and reduce bandwidth usage, particularly in adapting to varying video sequences and transmission conditions.
Innovation Solution
The method involves receiving a bitstream and enabling or disabling coding modes based on flags within the bitstream, allowing for control of coding modes at sequence, slice, or picture levels, using flags like sps_bdof_enabled_flag and slice_disable_bdof_dmvr_flag to manage tools like bi-directional optical flow, prediction refinement with optical flow, and decoder side motion vector refinement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If coding modes are controlled at sequence level only, then device complexity is reduced, but adaptability to varying video sequences and transmission conditions deteriorates
Solution Approach 1:
The patent segments the coding mode control into multiple hierarchical levels: sequence level (sps_bdof_enabled_flag), picture level (pic_bdof_enabled_flag), and slice level (slice_disable_bdof_dmvr_flag). This segmentation allows the system to apply global defaults at sequence level while enabling fine-grained adaptation at lower levels, resolving the contradiction between complexity and adaptability.
Solution Approach 2:
The patent enables different coding modes (BD 0F, DMVR, PROF) to be controlled independently at different granularities. Specific slices or pictures within a sequence can have customized coding mode configurations based on local video characteristics, allowing high adaptability where needed while maintaining simplicity in other regions.
2Productivity
If multiple coding modes are enabled for all video sequences, then coding efficiency is improved, but computational complexity increases
Solution Approach 1:
The patent introduces dynamic control mechanisms where coding modes are not statically enabled or disabled but are adaptively selected based on video content characteristics, transmission conditions, and quality requirements. The multi-level flag system allows the encoder to dynamically enable BD 0F, DMVR, or PROF only for specific pictures or slices where they provide the most benefit, optimizing the trade-off between coding efficiency and computational complexity.
Solution Approach 2:
The patent changes the parameter state of coding modes from fixed (always on/off) to variable (conditionally on/off based on flags). By introducing control flags at sequence, picture, and slice levels, the system can adjust the activation state of coding modes to match local video characteristics, achieving high coding efficiency only where computationally beneficial.
3Adaptability or versatility
If coding modes are controlled at lower levels (slice/picture), then adaptability is improved, but device complexity and signaling overhead increase
Solution Approach 1:
The patent implements a nested control structure where sequence-level flags (sps_bdof_enabled_flag) provide the outermost layer of control, picture-level flags (pic_bdof_enabled_flag) provide an intermediate layer, and slice-level flags (slice_disable_bdof_dmvr_flag) provide the innermost layer. Each level can override or refine the settings of higher levels, creating a hierarchical nesting that enables fine-grained adaptability while maintaining a structured, manageable control framework.
Data Source
AI summary
The present disclosure provides methods and apparatuses for controlling a coding mode for video data. The methods and apparatuses include receiving a bitstream of video data; enabling or disabling a coding mode for a video sequence, based on a first flag in the bitstream; and determining whether controlling of the coding mode is enabled or disabled at a level lower than a sequence level, based on a second flag in the bitstream.