FFMPEG is a popular open source freeware streaming tool, available for multiple operating systems.
It is command line based.

With FFMPEG you can also transcode audio codecs or streaming formats and stream via RTP to e.g. a Barix Exstreamer.

On the Streaming Client firmware you use optimally the Priority port to receive such FFMPEG stream.
In the Streaming Client setup the port number 4444 is already used in URL1, for that reason a different port
number should be configured on the Priority Port, e.g. port number 5555. 

Here in this example is used a WAV file (evacu_B.wav) in PCM 16-bit  441000 Hz mono little endian (LSB).
Unfortunately FFMPEG and the Streaming Client are using different payload types for this audio format,
so the streaming format has to be converted to  "PCM 16-bit 44100 Hz mono big endian (MSB)" to be compatible
(many RTP payload types are not standardized for that reason that could happen, payload types for MP3
and G.711 8 kHz codec are standardized and are also compatible!).

For that use the command :

ffmpeg -re -i evacu_B.wav -acodec pcm_s16be -ar 44100 -ac 1 -f rtp rtp://