Arithmetic Bitstream Entry Points for Parallel 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

VSEngineering 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

Engineering Contradiction:

Improvedecoding speedVSAvoidcoding procedure complexity

Core Design Contradiction:

SpeedVSDevice complexity

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 complete decoding context (interval state, probability estimates) at its entry point, enabling independent processing without requiring prior segments to be decoded first.

Inventive Principle:

Principle #1Segmentation

2Productivity

If multiple decoders process different parts of bitstream in parallel, then decoding speed improves, but entry point information and state management complexity increases

Engineering Contradiction:

Improvedecoding efficiencyVSAvoidstate management complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

Entry point information including interval state and probability estimates is prepared and embedded in advance at specific positions in the bitstream during encoding. This preliminary preparation eliminates the need for complex runtime state synchronization and management, allowing decoders to independently initialize from pre-computed states without complex coordination overhead.

Inventive Principle:

Principle #10Preliminary action

3Speed

If entry point information is provided for parallel decoding, then decoding parallelization is enabled, but bitstream size increases due to additional metadata

Engineering Contradiction:

Improveparallel decoding speedVSAvoidbitstream size

Core Design Contradiction:

SpeedVSQuantity of substance

Solution Approach 1:

The interval state parameters (such as range and offset values) are dynamically adjusted and renormalized during the encoding process to maintain numerical stability and precision. This parameter management ensures that entry point information can be compactly represented without requiring excessive precision, thereby minimizing the overhead added to the bitstream while enabling parallel decoding functionality.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250365015A1Arithmetic encoder for arithmetically encoding and arithmetic decoder for arithmetically decoding a sequence of information values, methods for arithmetically encoding and decoding a sequence of information values and computer program for implementing these methods

Publication Date: 2025.11.27 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

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.