Appendix D

Audio-visual supervision

Technical requirements. Audio supervision is accomplished via the telephone system. Using the Asterisk PBX system, CallWeb offers a way to easily connect with an on-going call. Video supervision is implemented using a VNC server installed on each interviewer station and a VNC client running on the supervisor station. TightVNC is a free implementation of the VNC protocol which has performed well in various installations. Refer to the TightVNC documentation for installation instructions relative to that software. The following assume the pre-installation of the Asterisk PBX and of TightVNC.

Operations. cwphone.cgi lists the phones lines in use and matches them with interviewer station IP addresses, interviewer name and project. The duration of the on-going call is also indicated. Once the supervisor station phone extension is supplied to cwphone.cgi, magnifying glass links are added to the page; clicking on one of them connects the supervisor phone to the on-going interview and pops a window showing the current state of the interviewer display.

Accessing recordings. If interview recording is activated in BASEprojets, corresponding .wav and .mp3 files are accessible from cwnav.cgi. Usual cwnav.cgi case selection tools can be used to focus on the cases of interest (e.g. completed interviews or cases handled by a certain interviewer). Selecting the "Display .wav/.mp3 files" checkbox adds a .wav/.mp3 column in the case-by-case output. Sound files are hyperlinked such that left-clicking opens the file with the sound application available on the local computer; it is also possible to save a local copy of the sound file by selecting the "Save target as" (or equivalent) command in the right-click context menu.

To the extent possible, sound file names give some indication about the content of the file. The name displayed starts with the date and time of the call, followed by the call sequence number (1 for the first call in a case), the language of the call (if available) and an indication of whether the call was a completed interview (CO) or not (UN). For example, in the image to the right, the last case contains a call made on October 14, 2009 at 8:22PM; it was the first call to the case and it led to a completed interview in French.

The real name of the file is longer than that displayed in cwnav.cgi. The underlying complete file name is prefixed with the project name and the case _telkey.


Installation. Assuming Asterisk and TightVNC are up and running, the rest of the installation required is as follows.

  • add the following context in /etc/asterisk/extension.conf and reload the Asterisk contexts:
    [ext-ecoute]
    exten => 8888,1,Answer
    exten => 8888,n,NoOp(cwphone.pl: ecoute=${ecoute})
    exten => 8888,n,ChanSpy(SIP/${ecoute}|q)
    exten => 8888,n,Hangup
  • on the Asterisk server, ensure that the supervisor station has access to the PBX software in /etc/asterisk/manager.conf
  • on the supervisor station:
    • ensure that "vncviewer" is installed
    • ensure that Perl is installed (which it is by default on a Linux station)
    • install the Net::Telnet Perl module
      • perl -MCPAN -e shell
      • install Net::Telnet
      • exit
    • copy the cwphone.pl script on the supervisor station and note down its location
    • install Firefox (version 1.5 or more)
    • in Firefox, install the StartALocalProgram extension (may require issuing the following command at the system prompt: "firefox startalocalprogram.xpi"; restart Firefox after installation)
    • in Firefox, enter the URL about:config and edit the following keys:
      • put the full path to Perl (usually /usr/bin/perl) in the following keys: extensions.startalocalprogram.launcherLocation and extensions.startalocalprogram.launcherLocation.linux (or mac or windows)
      • put the full path to cwphone.pl in the following keys: extensions.startalocalprogram.programToLaunch and extensions.startalocalprogram.programToLaunch.linux (or mac or windows)

Appendix D

Audio-visual supervision

Technical requirements. Audio supervision is accomplished via the telephone system. Using the Asterisk PBX system, CallWeb offers a way to easily connect with an on-going call. Video supervision is implemented using a VNC server installed on each interviewer station and a VNC client running on the supervisor station. TightVNC is a free implementation of the VNC protocol which has performed well in various installations. Refer to the TightVNC documentation for installation instructions relative to that software. The following assume the pre-installation of the Asterisk PBX and of TightVNC.

Operations. cwphone.cgi lists the phones lines in use and matches them with interviewer station IP addresses, interviewer name and project. The duration of the on-going call is also indicated. Once the supervisor station phone extension is supplied to cwphone.cgi, magnifying glass links are added to the page; clicking on one of them connects the supervisor phone to the on-going interview and pops a window showing the current state of the interviewer display.

Accessing recordings. If interview recording is activated in BASEprojets, corresponding .wav and .mp3 files are accessible from cwnav.cgi. Usual cwnav.cgi case selection tools can be used to focus on the cases of interest (e.g. completed interviews or cases handled by a certain interviewer). Selecting the "Display .wav/.mp3 files" checkbox adds a .wav/.mp3 column in the case-by-case output. Sound files are hyperlinked such that left-clicking opens the file with the sound application available on the local computer; it is also possible to save a local copy of the sound file by selecting the "Save target as" (or equivalent) command in the right-click context menu.

To the extent possible, sound file names give some indication about the content of the file. The name displayed starts with the date and time of the call, followed by the call sequence number (1 for the first call in a case), the language of the call (if available) and an indication of whether the call was a completed interview (CO) or not (UN). For example, in the image to the right, the last case contains a call made on October 14, 2009 at 8:22PM; it was the first call to the case and it led to a completed interview in French.

The real name of the file is longer than that displayed in cwnav.cgi. The underlying complete file name is prefixed with the project name and the case _telkey.


Installation. Assuming Asterisk and TightVNC are up and running, the rest of the installation required is as follows.

  • add the following context in /etc/asterisk/extension.conf and reload the Asterisk contexts:
    [ext-ecoute]
    exten => 8888,1,Answer
    exten => 8888,n,NoOp(cwphone.pl: ecoute=${ecoute})
    exten => 8888,n,ChanSpy(SIP/${ecoute}|q)
    exten => 8888,n,Hangup
  • on the Asterisk server, ensure that the supervisor station has access to the PBX software in /etc/asterisk/manager.conf
  • on the supervisor station:
    • ensure that "vncviewer" is installed
    • ensure that Perl is installed (which it is by default on a Linux station)
    • install the Net::Telnet Perl module
      • perl -MCPAN -e shell
      • install Net::Telnet
      • exit
    • copy the cwphone.pl script on the supervisor station and note down its location
    • install Firefox (version 1.5 or more)
    • in Firefox, install the StartALocalProgram extension (may require issuing the following command at the system prompt: "firefox startalocalprogram.xpi"; restart Firefox after installation)
    • in Firefox, enter the URL about:config and edit the following keys:
      • put the full path to Perl (usually /usr/bin/perl) in the following keys: extensions.startalocalprogram.launcherLocation and extensions.startalocalprogram.launcherLocation.linux (or mac or windows)
      • put the full path to cwphone.pl in the following keys: extensions.startalocalprogram.programToLaunch and extensions.startalocalprogram.programToLaunch.linux (or mac or windows)