This repository contains a version of the Helix MP3 Encoder with some maintenance work applied to build on modern systems. This targets mostly Linux-based machines (tested on x86-64 and ARM), but project files for Visual Studio 2015 are also included.

This repository contains a source code copy of the Helix MP3 Encoder in the directory ./hmp3. Please study ./hmp3/LICENSE.txt for licensing information.

Files in this repository outside of the ./hmp3 directory are licensed under the terms of the MIT License, unless noted otherwise.

A Makefile tested on Linux is provided in this directory. With the usual build systems installed, a simple make should create a hmp3 program binary in builds/release, along with compiled object files.

A binary with debug symbols can be generated with make debug.

The encoder is documented over at the HydrogenAudio Wiki page of the Helix MP3 encoder.

• Create a ~128 kbps VBR MP3 file:

  hmp3 input.wav output.mp3

• Create a 128 kbps CBR MP3 file:

  hmp3 input.wav output.mp3 -B64

  (Note that -B denotes the bitrate per channel, thus stereo input files are being encoded with 128 kbps.)

• Create a ~185 kbps VBR MP3 file, encode frequencies above 16 kHz, with a highpass filter of 19 kHz applied:

  hmp3 input.wav output.mp3 -V100 -HF2 -F19000