This is a program to cast audio and video from your macOS, or Linux desktop to your Google Cast devices or Sonos speakers. It is written in Python, and it streams via node.js, ffmpeg, or avconv.
Mkchromecast is capable of using lossy and lossless audio formats provided that ffmpeg, avconv (Linux), or parec (Linux) are installed. It also supports Multi-room group playback, and 24-bits/96kHz high audio resolution. Linux users also can configure ALSA to capture audio.