flac is the command-line file encoder/decoder. The encoder currently supports as input RIFF WAVE, Wave64, RF64, AIFF, FLAC or Ogg FLAC format, or raw interleaved samples. The decoder currently can output to RIFF WAVE, Wave64, RF64, or AIFF format, or raw interleaved samples. flac only supports linear PCM samples (in other words, no A-LAW, uLAW, etc.), and the input must be between 4 and 24 bits per sample. This is not a limitation of the FLAC format, just the reference encoder/decoder.

source https://xiph.org/flac/documentation_tools_flac.html