Entropy Decoder Mode Switching for Adaptive Coding Complexity
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Solution Overview
Problem
Current media codecs face challenges in achieving a balance between coding complexity and efficiency, particularly in handheld devices with limited energy resources, where simpler codecs are needed for lower complexity but more complex codecs offer better efficiency and backwards compatibility.
Innovation Solution
A decoder and encoder system that switches between low-complexity and high-efficiency modes by selecting from multiple entropy decoding/encoding schemes based on probability estimates, allowing for adaptive processing to optimize energy usage and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If arithmetic coding schemes are used for entropy coding, then coding efficiency is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic mode switching between CABAC (arithmetic coding) and CAVLC (variable length coding) based on profile/level parameters and data characteristics. The decoder can adaptively select the appropriate entropy decoding scheme during operation, transitioning from static to dynamic complexity management, thereby achieving high coding efficiency when needed while maintaining lower complexity options when sufficient.
Solution Approach 2:
The patent changes the operational parameters of the entropy decoder by introducing profile and level indicators that control the activation of CABAC versus CAVLC. By modifying these control parameters based on data characteristics and device capabilities, the system can adjust the complexity-efficiency trade-off dynamically, resolving the contradiction between fixed complexity and variable performance requirements.
2Productivity
If main profile conform decoders are used to support CABAC, then coding efficiency is improved, but energy consumption increases due to higher complexity
Solution Approach 1:
The patent enables dynamic adaptation of decoder complexity by switching between CABAC and CAVLC modes based on profile/level parameters. This dynamic approach allows mobile devices to use high-efficiency CABAC when energy is available and processing power is sufficient, while automatically falling back to lower-complexity CAVLC when energy constraints are tighter, thus resolving the energy-complexity contradiction.
Solution Approach 2:
The patent introduces profile and level parameters that control the operational state of the decoder. By changing these parameters based on device energy status and data characteristics, the system can optimize the balance between coding efficiency and energy consumption, allowing main profile decoders to operate in high-efficiency mode only when appropriate.
3Device complexity
If baseline profile is used for lower complexity, then device complexity is reduced, but coding efficiency decreases
Solution Approach 1:
The patent segments the entropy decoding functionality into two distinct paths: CABAC for high efficiency and CAVLC for low complexity. By dividing the overall decoding process and providing separate implementation paths, the system allows devices to select the appropriate segment based on their capabilities, resolving the contradiction between complexity and efficiency by making both options available rather than forcing a single approach.
Solution Approach 2:
The patent creates a universal decoder architecture that can perform both CABAC and CAVLC operations by controlling the activation of different entropy decoding schemes through profile/level parameters. This multi-functional design allows a single decoder to serve both low-complexity and high-efficiency requirements, eliminating the need for separate dedicated hardware for each profile type.
4Productivity
If high-efficiency modes are activated, then coding efficiency is improved, but backwards compatibility requirements increase complexity
Solution Approach 1:
The patent implements dynamic mode selection where the decoder can switch between CABAC and CAVLC based on profile/level parameters embedded in the bitstream. This dynamic capability allows high-efficiency CABAC to be used when the encoder signals its use, while automatically falling back to CAVLC for compatibility with baseline profile streams, thus achieving both high efficiency and backwards compatibility without permanently increasing hardware complexity.
Solution Approach 2:
The patent uses profile and level parameters as control mechanisms that change the operational state of the decoder. By modifying these parameters based on the encoded data's requirements, the system can activate high-efficiency modes when appropriate while maintaining the capability to process legacy baseline profile data, resolving the contradiction between efficiency enhancement and compatibility requirements.
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.