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     1 README version 22jun2005
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     2 
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     3 Welcome to intercom, a Voice over IP speaker-phone conference 
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     4 application. The application can:
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     5 - dial a intercom partner via short-dial buttons
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     6 - make a RTP connection to transport your voice over IPv4
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     7 - make a telephone conference
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     8 - support wideband codec (16kHz sample frequency)
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     9 
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    10 Intercom is still very limited. But the things it can do, it does
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    11 very well!
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    12 
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    13 
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    14 Modify file ~/.intercom.conf for your short-dial labels
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    15 and your IP-addresses.
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    16 
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    17 To start the application enter
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    18 
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    19   intercom
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    20   
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    21 Read shell script /usr/local/bin/intercom to get an idea of what is 
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    22 going on. For better echo cancellation start intercom with the -m or
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    23 -l option.
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    24 
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    25 For a first test talk to yourself by clicking the button for your own
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    26 IP-address, e.g. EDDF TEC2 if your computer is 192.168.1.2.
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    27 The button should become green.
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    28 Attention: A short click (less then 300ms) toggles on/off, a long
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    29 click works as push-to-talk.
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    30 
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    31 ATTENTION: The intercom application needs PCM out for playback. This
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    32 hardware device is used also by other sound programs like MP3 players 
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    33 (e.g. xmms) or WAV record/playback programs like sweep and audacity. The
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    34 intercom application blocks (freezes) as long as another program uses 
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    35 PCM out. There are ways around this like using sound daemons aRTs or 
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    36 esound. But this is outside of the intercom application.
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    37 
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    38 If you dial another intercom station, you get an one-way connection from
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    39 your microphone to the loudspeaker of your intercom partner. If your 
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    40 partner clicks on the correct button (the magenta one), both of you have 
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    41 a two-way communication. Now you or your partner can dial more intercom
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    42 stations to make a conference with maximum 6 stations.
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    43 Note: Start intercom with the -t option to get "everybody can talk and 
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    44 listen with everybody else".
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    45 
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    46 
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    47 Read the file 
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    48 http://home.arcor.de/andreadrian/intercom/draft-conference-01.txt 
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    49 for more information.
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    50 
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    51 
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    52 Supported royalty free Codecs:
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    53 For License see ITU-T G.191 or IETF RFC3951
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    54 
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    55 Narrowband (8kHz sample frequency):
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    56 -----------------------------------
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    57 IETF iLBC           15.2kBit/s  Global IP Sound iLBC Public License
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    58 ITU-T G.711 A-law   64kBit/s    ITU-T SOFTWARE TOOLS' GENERAL PUBLIC LICENSE
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    59 ITU-T G.711 u-law   64kBit/s    ITU-T SOFTWARE TOOLS' GENERAL PUBLIC LICENSE
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    60 ITU-T G.726 32kbs   32kBit/s    ITU-T SOFTWARE TOOLS' GENERAL PUBLIC LICENSE
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    61 3GPP GSM            13.2kBit/s  ITU-T SOFTWARE TOOLS' GENERAL PUBLIC LICENSE
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    62 
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    63 Wideband (16kHz sample frequency):
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    64 ----------------------------------
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    65 Speex               27.8kBit/s  Xiph.org license (BSD license variant)
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    66 
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    67 Author: Andre Adrian
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    68 E-Mail: Andre dot Adrian at dfs dot de
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    69 Postal: DFS Tower Frankfurt
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    70         Mr. Andre Adrian
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    71         Flughafen Gebaeude 501
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    72         60549 Frankfurt, Germany
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