Module constriction::stream::stack

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Fast and Near-optimal compression on a stack (“last in first out”)

This module provides the AnsCoder, a highly efficient entropy coder with near-optimal compression effectiveness that operates as a stack data structure. It implements the Asymmetric Numeral Systems (ANS) compression algorithm [1].

Comparison to sister module queue

ANS Coding operates as a stack, which means that encoding and decoding operate in reverse direction with respect to each other. The provided implementation of ANS Coding uses a single data structure, the AnsCoder, for both encoding and decoding. It allows you to interleave encoding and decoding operations arbitrarily, which is in contrast to the situation in the sister module queue and important for advanced compression techniques such as bits-back coding in hierarchical probabilistic models.

The parent module contains a more detailed discussion of the differences between ANS Coding and Range Coding .

References

[1] Duda, Jarek, et al. “The use of asymmetric numeral systems as an accurate replacement for Huffman coding.” 2015 Picture Coding Symposium (PCS). IEEE, 2015.

Structs

  • AnsCoder
    Entropy coder for both encoding and decoding on a stack.

Type Aliases