vac-enc

Opus encoding using the SoX resampler

The Opus audio format only supports a few sample rates, which can limit its coding efficiency if resampling is not performed correctly. While many resampling programs are effective, the SoX resampler is considered to be the best. This program uses the SoX resampler to convert audio to a supported sample rate for Opus encoding.

vac-enc v0.0.X | Opus encoding using the SoX resampler
Library Versions:
	Opus: libopus 1.4
	Opusenc: libopusenc 0.2.1
	SOXR: libsoxr 0.1.3
Usage: vac-enc [16-bit Little Endian WAVE input] [output.ogg] [kb/s]

Build instructions

There are two build systems present for building vac-enc; Zig and cmake. We recommend using Zig, but cmake instructions will be provided in the next section.

Zig

0. Before building, make sure you have the libsoxr, libopus, and libopusenc libraries installed, as well as zig at least version 0.11.0. vac-enc uses the pkg-config utility to find these libraries, so make sure they are installed and the PKG_CONFIG_PATH environment variable is set correctly.

1. Clone the repository and navigate to the cloned directory.

git clone https://github.com/gianni-rosato/vac-enc.git
cd vac-enc/

2. Build the project.

zig build

The vac-enc binary will be located in zig-out/bin/. Fome there, you can move it to a location in your PATH (like /usr/local/bin) or use it directly.

CMake

0. Before building, make sure you have the libsoxr, libopus, and libopusenc libraries installed, as well as cmake at least version 3.16. vac-enc uses the pkg-config utility to find these libraries, so make sure they are installed and the PKG_CONFIG_PATH environment variable is set correctly.

1. Clone the repository and navigate to the cloned directory.

git clone https://github.com/gianni-rosato/vac-enc.git
cd vac-enc/

2. Build the project using the script in build/build.sh.

cd build/
./build.sh

The vac-enc binary will be located in build/. From there, you can move it to a location in your PATH (like /usr/local/bin) or use it directly.

Usage

vac-enc is a command-line program that takes three arguments: the input file, the output file, and the bitrate. The input file must be a 16-bit little-endian WAVE file, and the output file must be an Ogg file. The bitrate is specified in kilobits per second.

vac-enc input.wav output.ogg 128

To create valid WAVE input files, you can use FFmpeg like so:

ffmpeg -i input.flac -c:a pcm_s16le output.wav

Extras

Also included is the vac-auto script, which can convert from various filetypes with FFmpeg.

License

This project is licensed under the GPL-3.0 License - see the LICENSE file for details.

Acknowledgments

• wavreader source is Copyright (C) 2009 Martin Storsjo