G.711 Audio Codec Library

Pure C G.711 mu-law/a-law encoder/decoder and L16 linear PCM utilities with canonical ITU algorithms. No external dependencies, fully unit-tested off-platform.

/*
 * es_codec — G.711 mu-law / a-law + L16. Canonical ITU/Sun algorithms
 * (public-domain lineage), reimplemented and unit-tested.
 *
 * Copyright (c) 2026 Varun Pratap Singh. MIT License.
 */
#include "es_codec.h"
#include <string.h>
#include <strings.h>

/* ---- G.711 mu-law ------------------------------------------------------- */

#define ULAW_BIAS 0x84
#define ULAW_CLIP 32635

/* exponent of the highest segment for a given (biased) magnitude high byte */
static const uint8_t ulaw_exp[256] = {
    0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,
    4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
    5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
    5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
    6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
    6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
    6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
    6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6

... (truncated -- full source via MCP)