'\" t.\" @(#)rat.1 3.1 97/02/22 .\" Copyright (c) 1997-2000 University College London..\" Written by Orion Hodson.\".TH rat 1 "14 January 2000".SH NAMErat \- unicast and multicast audio conferencing tool.SH SYNOPSIS.B rat    .RB [options] .I address/port.SH DESCRIPTION.LP.I RAT is a network audio conferencing and streaming application withsupport for multiple sampling rates, error concealment, and redundantaudio encoding.  Transmissions can be between two participants directly(unicast) or between a group of participants on a common multicastaddress.To initiate a unicast conference the user specifies the .I address of the destination host name or IP address and a port number.  To participate in a multicast conference a Class D group address should be specifiedtogether with a .I port number.  The application uses the greatest even integer less than or equal to the port specified for data (RTP) and the port above for control messages (RTCP).  The protocols RTP and RTCP used are specified in RFC 1889..SH OPTIONSThe following options are supported:.TP.BI -agc " 1|0"Enable automatic gain control (AGC)..TP.BI -allowloopbackCauses rtp packets to be loopbacked during multicastsessions..TP.BI \-crypt " key"Enable encryption, with the specified key. Encryption isdone using DES, and is believed compatible with encryptingversions of vat..TP.BI -C " name"Sets the RAT window title to .I name.	.TP.BI -E " email"Sets the .I emailaddress transmitted to remote participants..TP.BI \-f " codec"Specifies the primary encoding used when transmitting audio..TP.BI -L " location"Sets the .I locationdescription transmitted to remote participants..TP.BI -N " username"Sets the .I username transmitted to remote participants..TP.BI -P " phone"Sets the .I phonenumber transmitted to remote participants..TP.BI -pt " type/codec"Specifies the payload type to be used for .I codec..TP.BI -r " codec/offset"Specifies the coding used for the redundant encoder and the offsetof the redundant encoding relative to the primary in audio frames..TP.BI -repair " method"Specifies the use of receiver based repair technique based on.I method.  This can currently be none or repeat.   .TP.BI -t " ttl"Specifies the TTL (time to live) value set in the packet headers.  This limits the scope of the packets. The following values are generally considered	appropriate:  .RS 10n.nf.ta   4 campus/organization 16 country 64 continent127 planet.fi.RE.TP.BI -silence " on|off"Turns silence suppression on or off..TP.B -versionDisplays the version number..SH USER INTERFACE.SS Main WindowThe main window of RAT is split into three sections.  At the top ofthe window are the audio device port and volume selectors, and themutes for incoming and outgoing audio.  In the middle the list ofparticipants shows local and remote conference members.  Activespeakers are highlighted. Clicking the left mouse button on the nameof a remote participant will display a user information panel, givingvarious reception statistics for that user.  Individuals can beselectively muted by clicking on them with the middle mouse button onthree button systems, or moving the mouse to the individual andpressing the m.  At the bottom of the window are buttons for theoptions panel, the about panel, and to quit.Pressing the right mouse button anywhere within the RAT window willtemporarily toggle the state of the audio input mute: this allows a"push-to-talk" mode of operation..SS OptionsRAT supports a large number of options and pressing the "options"button will launch the optinos panel.  The best approach to see whatis available is to go and explore.  The options panel has a categorymenu at the top and by clicking on it options in the differentcategories are presented.  .TP .B PersonalUser details that are conveyed to other conference participants..TP	.B TransmissionAllows the selection of codec used for transmission, the setting ofthe number, of units of audio per packet, and the selection ofredundant audio data..TP.B ReceptionOptions that control how received audio is decoded..TP.B AudioOptions to select and configure the available audio device, andfeatures that pertain to audio handling (i.e. silence suppression,agc, audio loopback, and echo suppression)..TP.B CodecsDisplays details on available codecs and allows for them to be assignedto alternate RTP payload numbers.  Map payload numbers at your own peril..TP.B SecurityAllows DES encryption of audio for incoming and outgoing streams..TP.B InterfaceAllows users to control balloon help, enable lip synchronization withsuitably modified versions of .I VIC, and displaying of windows for reception quality and file playback and recording.	.SH EXAMPLESTo start a unicast session between the current host and the hostshrew.cs.ucl.ac.uk using port 12000 type:		rat shrew.cs.ucl.ac.uk/12000To join a multicast session on group address 224.5.6.7 and port 8110type, using primary encoding of dvi and a secondary encoding of lpc:		rat -f dvi/lpc 224.5.6.7/8110.SH AUTHORSThis version of RAT was written by Orion Hodson<O.Hodson@cs.ucl.ac.uk> and Colin Perkins <C.Perkins@cs.ucl.ac.uk> inthe Networked Multimedia Group, University College London.  MarkusIken contributed the 3d rendering code. Bob's Olson and Lindell contributedthe ALSA audio interface.The first version of RAT was developed by Vicky Hardman <V.Hardman@cs.ucl.ac.uk> and Isidor Kouvelas <I.Kouvelas@cs.ucl.ac.uk>at University College London.  The DES encryption was written bySaleem Bhatti <S.Bhatti@cs.ucl.ac.uk> and integrated by Darren Harris.RAT has been supported by the following projects:.RS 4.TSMICE	 Multimedia Conferencing in Europe (ESPRIT)MERCI	 Multimedia European Research Conferencing IntegrationReLaTe	 Remote Language Teaching for Super Janet (BT/JISC)RAT	 Robust Audio Tool (EPSRC/BT).TE.REThis software has benefited from hardware donations by SunMicrosystems and Hewlett Packard, and software donations by Microsoft..SH ACKNOWLEDGEMENTSWe thank Roy Bennett, Davide Cavagnino, Jon Crowcroft, Ross Finlayson,Atanu Ghosh, Terry Gibbons, Jeremy Hall, Mark Handley, Marcus Iken,Iain McKay, Roman Kurmanowyts, Robert Olson, Fulvio Risso, RoyRodenstein, Lorenzo Vicisano, Anna Watson, Michael Wallbaum, Hui Zhao,and our collegues at UCL who have provided countless suggestions andextended good humour through the buggy pre-releases.Modifications for HP-UX by Terje Vernly <terjeve@usit.uio.no>and Geir Harald Hansen <g.h.hansen@usit.uio.no>.This software is derived, in part, from publically available source code with the following copyright:Copyright (c) 1991-1993,1996 Regents of the University of California.Copyright (c) 1992 Stichting Mathematisch Centrum, Amsterdam.Copyright (c) 1991,1992 RSA Data Security, Inc.Copyright (c) 1992 Jutta Degener and Carsten Bormann, Technische Universitaet Berlin.Copyright (c) 1994 Henning Schulzrinne.Copyright (c) 1994 Paul Stewart.This product includes software developed by the Computer SystemsEngineering Group and by the Network Research Group at Lawrence Berkeley Laboratory. Encryption features of this software use the RSA Data Security, Inc. MD5 Message-Digest Algorithm..SH FEEDBACKPlease send comments, bug-reports, patches, and suggestions torat-trap@cs.ucl.ac.uk.Please check http://www-mice.cs.ucl.ac.uk/multimedia/software forlatest release information.