Lite Encoding Library

A header-only, adaptive entropy coding library written in C99.

Overview

Lite Encoding implements a Rice-Golomb backend paired with a Move-To-Front (MTF) Alphabet. This combination captures categorical redundancy (repetitive patterns) and numerical sparsity. The library provides also small delta (signed) and small literal encoding functions with a soft K adaptation.

MFT Heuristic

Unlike standard MTF, this library uses a low-pass promotion strategy (target = index >> 1). This filter prevents "alphabet thrashing" by requiring a symbol to appear multiple times before it can dominate the zero-index slot.

Soft K Adaptation

The library employs a "Soft K" mechanism to track data magnitude trends. Instead of switching the Rice parameter $k$ immediately upon seeing a large value, it maintains a k_trend counter.

$k$ only increments or decrements when the trend exceeds LE_K_TREND_THRESHOLD (12). This heuristic ensures that the coder remains stable in the presence of noise while eventually adapting to new statistical regions in the bitstream.

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Core API

Function	Usage
le_encode_symbol	Encodes 8-bit data using the MTF alphabet. Best for repetitive patterns.
le_encode_literal	Encodes raw values directly via Rice coding. Best for small numbers.
le_encode_delta	Encodes signed differences using ZigZag + Rice. Best for small delta

Of course equivalent decoding functions are available : le_decode_symbol, le_decode_literal, le_decode_delta.

Maximize efficiency through specialization: use multiple model instances to track different data streams. One model per data type ensures the history remains relevant and the compression stays tight.

Example

#include"lite_encoding.h"size_tcompress_data(uint8_t*src, uint8_t*dst, size_tsize)
{
le_streams;
le_modelm;
le_init(&s, dst, size);
le_model_init(&m);
le_begin_encode(&s);
for(size_ti=0; i<size; ++i)
le_encode_symbol(&s, &m, src[i]);
returnle_end_encode(&s);
}