Ffmpeg

avconv

avconv -f alsa -ac 1 -i hw:1,0 -acodec pcm_s16le -ar 22050 -f rtp rtp://192.168.1.108:1234

-f alsa — This tells avconv what type of input audio device we are using.

Since the microphone is a hardware device, it is handled by ALSA.

If a streaming a file, put the format of the file here.

Look at other audio formats by running

avconv -formats

-ac 1 — Number of audio channels in the input stream.

-i hw:1,0 — input audio device is at the hardware address hw:1,0, where 1 is the card number and 0 is the device number on that card.

-acodec pcm_s16le — output format for the stream. The s16le part indicates each audio sample is 16 bits in Little Endian format.

avconv -codecs