Free software to do audio/video streaming

Icecast install

sudo aptitude install icecast2

The installed will ask you to set

the domain name: keep it localhost
access passwords

config

/etc/icecast2

Icecast clients

Extensive list

Ezstream

A command line source client for Icecast media streaming servers.

In its basic mode of operation, it streams media files or data from standard input without reencoding and thus requires only very little CPU resources. It can also use various external decoders and encoders to reencode from one format to another,