libao is a cross-platform audio library that allows programs to output audio using a simple API on a wide variety of platforms. On FreeBSD, it currently supports: * null output * raw output * AU files * WAV files * OSS (Open Sound System) And optionally: * ESD (ESounD or Enlightened Sound Daemon) * NAS (Network Audio System) * PulseAudio WWW: https://www.xiph.org/ao/