SoX

SoX (Sound eXchange) is the definitive open-source command-line audio processing tool, often called the Swiss Army knife of audio manipulation. Originally developed at the University of Wales by Lance Norskog and Chris Bagwell, it has been maintained since the early 1990s and remains the most widely used audio utility in Linux environments. SoX can read, write, and convert between over 30 audio formats including WAV, AIFF, AU, FLAC, Ogg Vorbis, MP3, Opus, AAC, raw PCM, GSM 06.10, IMA ADPCM, MS ADPCM, and VOC. It operates as both a batch processor (reading and writing files) and a real-time effects processor on live audio streams. Effects include: gain normalization, pitch shifting, tempo changing, speed adjustment, reverb, echo, chorus, flanger, phaser, tremolo, lowpass/highpass/bandpass/bandreject filters, noise reduction, compander (dynamic range compression/expansion), silence removal, fade in/out, trim, splice, and spectrogram generation. Mathematical operations include mixing, concatenation, and merging channels. The tool also provides format conversion between sample rates (using high-quality resampling algorithms) and bit depths. SoX is written in C and available on Linux, macOS, Windows, and BSD. It serves as the audio backend for numerous applications including Audacity plugins and FFmpeg pipelines.