Arithmetic Coding Entry Points for Parallel Bitstream Decoding
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Solution Overview
Problem
Existing arithmetic decoding processes, such as context-based adaptive binary arithmetic coding (CABAC), are highly sequential and cannot be effectively parallelized, limiting decoding speed.
Innovation Solution
An encoding and decoding concept that allows for parallel decoding by providing entry point information in the bitstream, enabling multiple decoders to process different parts of the bitstream simultaneously, and includes an arithmetic encoder and decoder that renormalize internal parameters and use subintervals based on probability estimates to resume decoding from a predetermined point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If arithmetic decoding is performed using traditional sequential methods (CABAC), then decoding accuracy is maintained, but decoding speed is limited due to inability to parallelize
Solution Approach 1:
The bitstream is divided into multiple independent segments, each with its own entry point information. Multiple decoders can process different segments in parallel, transforming a sequential process into a parallel one. Each segment contains sufficient context information (entry point data) to be decoded independently, enabling simultaneous processing without losing decoding accuracy.
Solution Approach 2:
Entry point information is prepared and embedded in the bitstream during the encoding phase. This preliminary action provides pre-calculated decoding state information at specific positions, allowing decoders to jump directly to those positions and resume decoding without processing previous data, thus enabling parallel processing while maintaining accuracy.
2Productivity
If multiple decoders process different parts of the bitstream simultaneously, then decoding speed is improved, but entry point information must be provided to enable resumption
Solution Approach 1:
Entry point information is extracted from the full decoding context and embedded as separate data elements in the bitstream at specific positions. This extracted information contains the essential state data needed to resume decoding at entry points, allowing parallel decoders to independently reconstruct the decoding state without accessing previous segment data.
Solution Approach 2:
Entry point information acts as an intermediary that bridges the gap between segmented bitstream portions. It provides the necessary decoding state context that would otherwise require processing of all preceding data, enabling decoders to jump directly to entry points and resume processing with complete context information.
3Reliability
If the bitstream is processed sequentially to maintain decoding accuracy, then information integrity is preserved, but processing time increases
Solution Approach 1:
The bitstream is segmented into independent processing units with entry points that contain sufficient context information for accurate decoding. This segmentation allows parallel processing while maintaining the integrity and accuracy of decoded information, as each segment can be decoded independently with complete context from its entry point.
Solution Approach 2:
Entry point information is prepared in advance during encoding, storing the necessary decoding state at specific positions. This preliminary preparation ensures that when parallel decoders resume at these points, they have accurate context information, preserving decoding reliability while eliminating the need to sequentially process all preceding data.
Data Source
AI summary
An encoding scheme is provided for arithmetically encoding a sequence of information values into an arithmetic coded bitstream by providing the bitstream with entry point information, allowing for resuming arithmetic decoding of the bitstream from a predetermined entry point onward. A respective decoding scheme is also provided. These encoding and decoding schemes provide more efficient encoding in view of the decoding speed.