libg722

Introduction

The G.722 module is a bit-exact implementation of the ITU G.722 specification for all three specified bit rates: 64,000 bps, 56,000 bps and 48,000 bps. It passes the ITU tests.

To allow fast and flexible interworking with narrowband telephony, the encoder and decoder support an option for the linear audio to be an 8 kHz stream. In this mode the codec is considerably faster, and still fully compatible with wideband terminals using G.722.

History

The code was originally written by Milton Anderson milton@thumper.bellcore.com from BELLCORE, and was modified by Chengxiang Lu and Alex Hauptmann from the Speech Group, School of Computer Science, Carnegie Mellon University, to be fairly fast and efficient while retaining high fidelity.

Steve Underwood steveu@coppice.org improved the code a lot later on and contributed it into several popular open source projects.

Himanshu Soni sonihimanshu@gmail.com has adjusted some coefficients to avoid overflows and underflows in the decoder.

Phil Schatzmann phil.schatzmann@gmail.com has added CMake glue and Arduino support.

Packaged as libg722 by Sippy Software, Inc.

Build and Install Library

macOS and Linux

git clone https://github.com/sippy/libg722.git
cmake -B libg722/build -S libg722
make -C libg722/build clean all test install

Note for macOS users: The library will be installed to ~/Library/libg722 by default. If you prefer a different location, you can specify it with:

cmake -B libg722/build -S libg722 -DCMAKE_INSTALL_PREFIX=/your/preferred/path

After installation, you may need to add the library path to your environment:

export DYLD_LIBRARY_PATH="$HOME/Library/libg722/lib:$DYLD_LIBRARY_PATH"

iOS

git clone https://github.com/sippy/libg722.git
cmake -B libg722/build-ios-device -S libg722 \
  -DCMAKE_SYSTEM_NAME=iOS \
  -DCMAKE_OSX_ARCHITECTURES=arm64 \
  -DCMAKE_OSX_SYSROOT=iphoneos \
  -DCMAKE_OSX_DEPLOYMENT_TARGET=12.0
make -C libg722/build-ios-device

Install Python Module With pip

The core package has no required NumPy dependency:

pip install G722

Install the optional NumPy decode backend with the numpy extra:

pip install "G722[numpy]"

This installs G722-numpy at the same version as G722. You can also install the addon package directly:

pip install G722-numpy

Build and Install Python Module From Source

The default source build installs the core package:

git clone https://github.com/sippy/libg722.git
pip install ./libg722

After installing the core package, build the optional NumPy backend from the same checkout:

LIBG722_PACKAGE_VARIANT=numpy-addon pip install ./libg722

Python Build Options

LIBG722_BUILD_MODE controls build profile for the main G722 extension:

• production: build with optimization (-O2, or /O2 on Windows).
• debug: build with -g3 -O0.
• auto (default): if . is a git repository and git is available, run git diff v{version} -- .; build in debug mode when it differs, otherwise production. If . is not a git repository or git is unavailable, use production.

LIBG722_PACKAGE_VARIANT controls which Python distribution is built from this repository:

• core (default): builds/publishes G722.
• numpy-addon: builds/publishes G722-numpy from python/G722_numpy_mod.c.

Python API

G722(sample_rate, bit_rate, use_numpy=None) accepts an optional use_numpy flag:

• True: return NumPy arrays from decode() (raises if G722-numpy is not installed).
• False: return Python array('h') from decode().
• omitted or None: use the G722-numpy backend when installed, otherwise return array('h').

Pull Library Into Your Docker Container

Published Docker images contain the installed library and public headers under /usr/local. The default-branch images are published with these tags:

• sippylabs/libg722:latest-debian_sid-slim
• sippylabs/libg722:latest-debian_12-slim
• sippylabs/libg722:latest-debian_13-slim
• sippylabs/libg722:latest-ubuntu_latest

Branch, release, pull request and SHA tags use the same base-image suffixes, for example <ref>-debian_12-slim.

ARG BASE_IMAGE=debian:sid-slim
ARG LIBG722_IMAGE=sippylabs/libg722:latest-debian_sid-slim
FROM ${LIBG722_IMAGE} AS libg722
FROM ${BASE_IMAGE} AS build
COPY --from=libg722 /usr/local/lib/libg722.* /usr/local/lib/
COPY --from=libg722 /usr/local/include/g722* /usr/local/include/

License

This code is mostly Public Domain. Library test code is under BSD 2-clause license.

See LICENSE for copyright details and each individual file for specifics.