This is a program to cast your macOS audio, or Linux audio to your Google Cast devices or Sonos speakers. It can also cast video files.

It is written for Python3, and it can stream via  node.js,parec (Linux), 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-bit/96kHz high audio resolution. Additionally, a system tray menu is available.

mkchromecast.com
github.com/muammar/mkchromecast