Robust Audio Tool (RAT)

The Robust Audio Tool (RAT) is a an open-source audio conferencing and streaming application that allows users to particpate in audio conferences over the internet. These can be between two participants directly, or between a group of participants on a common multicast group.

RAT require no special features for point-to-point communication, just a network connection and a soundcard. For multiparty conferencing RAT uses IP multicast and therefore all participants must reside on a multicast capable network. RAT is based on IETF standards, using  RTP above UDP/IP as its transport protocol, and conforming to the  RTP profile for audio and video conference with minimal control.

RAT features a range of different rate and quality codecs, receiver based loss concealment to mask packet losses, and sender based channel coding in the form of redundant audio transmission. It offers better sound quality relative to the network conditions than most audio tools available. It also features encryption so you can keep your conversations private.

RAT is a cross platform tool which is now available for Linux and WinXP. In the past it was also maintained for use a variety of operating systems including: FreeBSD, HP-UX, IRIX, NetBSD, Solaris, SunOS, and Windows 95/NT. Users are welcome to test and contribute code for any of these other OSes. Please let us know or contribute to the wiki.

The source code is publicly available for porting to other platforms and for modification by others. Current releases (4.x) have an open source  license. Source code for older versions of RAT can be obtained from the  Mice download page and by  anonymous CVS. Note, however, that the Mice site and CVS repository are no longer active. Development of the Mbone tools now takes place under the  SUMOVER project, which has made available a new UCL Subversion repository and this Trac system.

RAT is just an audio application, it does not perform call services like user location, neither does it listen to session announcements to discover advertised multicast sessions. For these purposes, it is recommended you use RAT in conjunction with the Session Directory ( SDR), or a similar application.