https://github.com/m4tx/rans-rs

rANS encoder and decoder for Rust
https://github.com/m4tx/rans-rs

asymmetric-numeral-systems compression entropy-coding rust

Last synced: about 2 months ago
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rANS encoder and decoder for Rust

• Host: GitHub
• URL: https://github.com/m4tx/rans-rs
• Owner: m4tx
• License: mit
• Created: 2022-07-16T23:36:58.000Z (over 2 years ago)
• Default Branch: master
• Last Pushed: 2024-02-11T15:46:18.000Z (11 months ago)
• Last Synced: 2024-10-31T11:57:16.823Z (2 months ago)
• Topics: asymmetric-numeral-systems, compression, entropy-coding, rust
• Language: Rust
• Homepage:
• Size: 49.8 KB
• Stars: 3
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
rans-rs

=======

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Ranged Asymmetric Numeral Systems (rANS) encoder and decoder. Under the hood,

this is a high-level wrapper over

[ryg-rans-sys](https://github.com/m4tx/ryg-rans-sys/).

ANS is a family of modern entropy coding methods introduced by Jarek Duda from

Jagiellonian University. It serves as an alternative to arithmetic and Huffman

coding, combining the performance and compression ratio of both. Many recent

compression algorithms, such as Facebook’s Zstandard, Apple’s LZFSE, or JPEG XL,

use ANS under the hood.

See the [ryg_rans](https://github.com/rygorous/ryg_rans) repository for more

details about the underlying implementation.

## Usage

Add the following to your `Cargo.toml`:

```toml

[dependencies]

rans = "0.4.0"

```

## Examples

```rust

use rans::byte_decoder::{ByteRansDecSymbol, ByteRansDecoder};

use rans::byte_encoder::{ByteRansEncSymbol, ByteRansEncoder};

use rans::{RansDecSymbol, RansDecoder, RansEncSymbol, RansEncoder, RansEncoderMulti};

const SCALE_BITS: u32 = 2;

// Encode two symbols

let mut encoder = ByteRansEncoder::new(1024);

let symbol1 = ByteRansEncSymbol::new(0, 2, SCALE_BITS);

let symbol2 = ByteRansEncSymbol::new(2, 2, SCALE_BITS);

encoder.put(&symbol1);

encoder.put(&symbol2);

encoder.flush();

let mut data = encoder.data().to_owned();

// Decode the encoded data

let mut decoder = ByteRansDecoder::new(data);

let symbol1 = ByteRansDecSymbol::new(0, 2);

let symbol2 = ByteRansDecSymbol::new(2, 2);

// Please note that the data is being decoded in reverse

assert_eq!(decoder.get(SCALE_BITS), 2); // Decoder returns cumulative frequency

decoder.advance(&symbol2, SCALE_BITS);

assert_eq!(decoder.get(SCALE_BITS), 0);

decoder.advance(&symbol1, SCALE_BITS);

```

## License

The project is licensed under the [MIT license](LICENSE).

## Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted

for inclusion in the project by you shall be licensed as MIT, without any

additional terms or conditions.

## Developing

### `pre-commit`

We encourage contributors to use predefined [`pre-commit`](https://pre-commit.com/)

hooks --- to install them in your local repo, make sure you have `pre-commit`

installed and run

```shell

pre-commit install

```