Entropy Decoder Mode Switching for Complexity-Efficiency Tradeoffs
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Solution Overview
Problem
Existing audio and video codecs face challenges in balancing coding complexity and efficiency, with some profiles being more complex and less efficient due to arithmetic coding schemes and backward compatibility requirements, which is problematic for handheld devices with limited energy resources.
Innovation Solution
A decoder and encoder system that switches between low-complexity and high-efficiency modes based on data stream requirements, using different entropy decoding/encoding schemes with adjustable probability estimates and control parameters to optimize complexity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If arithmetic coding schemes are used to improve coding efficiency, then compression efficiency is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic mode switching between CA VLC and CA BAC entropy coding schemes based on profile requirements. The decoder can adaptively select the appropriate coding mode (low-complexity CA VLC or high-efficiency CA BAC) depending on the active profile, allowing the system to optimize between complexity and efficiency dynamically rather than being fixed to one approach
Solution Approach 2:
The patent changes the operational parameters of the entropy decoder by enabling/disabling specific coding features based on profile activation. When main profile is active, CA BAC is enabled with full arithmetic coding functionality; when baseline profile is active, the system switches to CA VLC with simplified variable-length coding, effectively changing the coding parameter set to match device capabilities
2Adaptability or versatility
If backward compatibility with baseline profile is maintained, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent segments the entropy decoding functionality into distinct modes (CA VLC and CA BAC) that can be independently activated based on profile requirements. This segmentation allows the decoder to implement only the necessary coding scheme for the active profile, reducing overall complexity while maintaining compatibility with both baseline and main profiles through selective activation
Solution Approach 2:
The entropy decoder is designed with multi-functionality to support both CA VLC and CA BAC coding schemes within a single implementation. The decoder can universally handle different profile requirements by switching between coding modes, eliminating the need for separate decoder implementations for baseline and main profiles
3Use of energy by moving object
If low-complexity coding is used to reduce energy consumption, then energy efficiency is improved, but compression efficiency deteriorates
Solution Approach 1:
The patent enables dynamic selection between low-complexity CA VLC and high-efficiency CA BAC modes based on the active profile and device capabilities. This dynamic approach allows handheld devices to operate in low-complexity mode for energy efficiency when baseline profile is active, while still accessing high-efficiency mode when main profile is active and device resources permit
Data Source
AI summary
A decoder for decoding a data stream into which media data is coded has a mode switch configured to activate a low-complexity mode or a high-efficiency mode depending on the data stream, an entropy decoding engine configured to retrieve each symbol of a sequence of symbols by entropy decoding using a selected one of a plurality of entropy decoding schemes, a desymbolizer configured to desymbolize the sequence of symbols to obtain a sequence of syntax elements, a reconstructor configured to reconstruct the media data based on the sequence of syntax elements, selection depending on the activated low-complexity mode or the high-efficiency mode. In another aspect, a desymbolizer is configured to perform desymbolization such that the control parameter varies in accordance with the data stream at a first rate in case of the high-efficiency mode being activated and the control parameter is constant irrespective of the data stream or changes depending on the data stream, but at a second lower rate in case of the low-complexity mode being activated.