Cathar vs PD Cleaner

Cathar is a free audio restoration toolkit for Linux and macOS, with tools to clean, enhance, and level recordings. It accepts WAV, MP3, FLAC, OGG, and M4A files, along with audio tracks inside MP4 and MKV video, and writes WAV, FLAC, or AIFF according to the output filename extension. Restoration options include denoising, de-humming, de-winding, de-clicking, de-clipping, de-reverberation, spectral repair, de-plosive processing, and rustle removal. Enhancement tools handle de-essing, breath removal, voice isolation, and bandwidth extension; loudness and peak normalization prepare delivery levels. The Rust toolkit uses inspectable and tunable DSP stages. Effects can run through the Rust crate or as command-line steps in a media pipeline. An optional machine-learning feature adds a deterministic GRU denoiser with safetensors weights. Optional terminal tools provide an audio player and spectrogram viewer. Cathar is licensed under Apache 2.0 or MIT, and its latest listed release is v0.8.0; the project describes itself as pre-1.0.

PD Cleaner is a free Windows app for reducing clicks, crackle, hiss, and hum in old recordings, particularly public-domain recordings made before 1926. Drop in a file and it analyzes its era, noise, and clicks; a Clean dial lets you adjust the cleaning. Its voicings cover cylinders, acoustic 78s, and early electric recordings, alongside an uncoloured transfer option. A live before-and-after spectrum analyzer can show a curve, waterfall, or both, and users can solo noise being removed. The app works as a VST3 insert in a DAW or as a standalone program. Folder-based batch processing with one preset is limited to the standalone version. Built-in formats are WAV, FLAC, AIFF, Ogg, MP3, and Opus; a free optional add-on provides AAC and more. It supports 24-bit archival exports and says it does not overwrite the original file. The maker describes it as offline software. The Windows release is open source under AGPLv3, and its build may show an unknown publisher warning when first run.