Balrogg losslessly recompresses Ogg Vorbis and Opus files, achieving archives typically 8-12% smaller than .ogg and 3-8% smaller than .opus files. Developed by Kamila Szewczyk and hosted at https://github.com/iczelia/balrogg, the tool is licensed under GNU GPL v3. Releases are not backwards or forwards compatible until v2.0.

Usage is straightforward: `balrogg e music.ogg music.blr` compresses and `balrogg d music.blr music.ogg` expands, with automatic codec detection. Batch processing with `-b` uses all available cores. Effort levels `-1` through `-9` (default `-9`) control compression; levels `-4` through `-9` decode at the same speed.

For a 5 MB music file, `-9` yields 9.8% Vorbis and 4.8% Opus reduction. The encoder refuses files it cannot reproduce exactly, including those with bad checksums or unsupported features. Opus support is limited to mono/stereo logical streams with channel mapping family 0.

Each file uses one thread, requires seekable I/O, and applies a 2 GiB process memory cap (adjustable via `BLR_MEMCAP`). Builds target Linux, Windows (MinGW), Windows 95 (i486), and MS-DOS (DJGPP).