The development of virtPresenter Software has stopped! We are concentrating our resources on Opencast Matterhorn Projekt here you can finde many experiences we made by deveolpint virtPresenter.


 

How To

How to use the virtPresenter manually

Recording

Starting a Recording / Controlling if the Recording-Computer works

The protocol for the Recording-Computer can easily be triggered manually. Thereby a recording can be started manually, if (for example) no virtPresenter Listener is required

In this manner problems with the Recording-Machine can be checked out.

First of all one should open a shell resp. the prompt in Windows.

Next Telnet has to be invoked. Telnet is supplied in nearly every OS. At Windows Vista it has to be activated (System Control -> Programs and Functions -> Enable/Disable Windows-Functions -> Telnet-Client).

For the following example we assume that the Recording-Computer has got the IP 192.168.0.1, the User Port is as preset 2222 and the password for the Recording-Machine is the default “secret“. For the Recording-ID we use “demo”. As a result, the video is going to be called “demo.mpg“. Outputs of the system have go a > preceded, the leftover are User-Inputs. 

telnet 192.268.0.1 2222
> 220 0 Videoserver 0.13 Uni-OS
auth secret
> 200 ok
status
> 202 idle
start demo
> 201 123456 seconds 
stop
> 200 ok
quit
> 221 close

For each condition of the Recording-Machine of course different Status-Reports can be submitted. Natürlich können je nach Zustand des Aufzeichnungsrechners andere Statusmeldungen zurückgeliefert werden. For a list of possible Status-Reports have a look at the Protocol of the Recording-Machine.

The most frequent sources of errors:

Reply for status “204 interrupted“

The last Recording has been stopped automatically (e.g. because the hard drive is full, or the timer has expired). In this case the “stop”-command has to be sent before another recording can be started again. At best one should check if there is still disc space available (“avail”).

Answer to start is „401 …“ and a more or less reasonable error description

Unfortunately the error report is not always reasonable and according to IVTV and Linux version it can differ. A frequent source of error is that either the wrong device has been chosen (the autodetect does not work for PVR-USB2, that has to be inscribed manually), or the program has (for any reason) no reading-rights for the device. In this case the quickest possibility is to sign up as root on the Recording-Computer (e. g. by SSH) and to type in chmod 777 /dev/video*. Permanently one should assure that the rights are set properly (which should be adjusted at /etc/rc.local).

Starting the VNC-Recording

The preparations are equivalent to the ones for the Video-Recording. The prompt has to be open and Telnet has to be installed. The passwords, IDs and servers stay the same as before.

This process can be combined on one machine together with the Video-Recording (Just start with the Log-In). If it is requested the VNC-Recording can also be executed on a different machine.

On the computer whose display shall be recorded (in our example 192.168.0.2) a VNC-Client has to be installed. For Windows-Machines we recommend UltraVNC, but there shouldn’t be any problem with other VNC-Servers (TightVNC, RealVNC). Unfortunately we haven’t found a practicable VNC-Server that we could advise for MacOS X machines yet (we haven’t tested the one in MacOS X 10.5).

At the VNC-Server a password has to be defined. For this example we use the password “virtpresenter”. Please notice that as the case may be the VNC-Port 5900 has to be shared at the firewall.

With the Recording-ID “demo” in this example the VNC-Recording is going to be saved as “demo-vnc.swf“ at the Recording-Machine. 

telnet 192.268.0.1 2222
> 220 0 Videoserver 0.13 Uni-OS
auth secret
> 200 ok
status
> 202 idle
vncrec demo 192.168.0.2 virtpresenter
> 201 123456 seconds 
stop
> 200 ok
quit
> 221 close

Possible mistakes

Unfortunately the error reports that are handed down by pyVNC2SWF and other used programs aren’t always reasonable. Besides lacking disk space, it’s possible that the connection to the VNC-Server can’t be established or passwords are wrong. For checking it’s advisable to connect with a simple VNC-Client to the VNC-Server at first.

A problem that often appears while setting up the Recording-Machine is the installation of a wrong version of “vncpasswd“. Unfortunately there is a set of versions of this program, which can’t be made out easily. The main difference is that some of these versions just read the password out of the keyboard-buffer, wherefore these versions can’t be scripted. If problems appear one should at best check if the file vncpass has been created and if there is a cryptic string inscribed (do not use the command “cat”, because the VNC-Password can contain non-printable chars).

Another problem occurs right after the start of the recording. Most of the VNC-Servers cut the connection, if modifications at the graphic settings are made. Therefore the resolution can’t be changed after the start of the recording! One also can’t change the output of the notebook to route the signal to the beamer! Basically one should have prepared the presentation and have the beamer running before the recording is started. As already mentioned this item does not concern the virtPresenter, but especially the VNC-Server. According to the VNC-Server it might work differently. In our tests it passed of as described.

Starting a VGA-Recording

As a last resort we want to point to the VGA-Recording. Actually it works almost like the Video-Recording. In advance it has to be guaranteed that the adequate epiphan VGA2USB-Hardware with the analogical divers is installed. Sadly we can’t give any advice for the installation of the Epiphan-Device. 

telnet 192.268.0.1 2222
> 220 0 Videoserver 0.13 Uni-OS
auth secret
> 200 ok
status
> 202 idle
vgarec demo 
> 201 123456 seconds 
stop
> 200 ok
quit
> 221 close

The file "demo-vga.avi" is created.

Possible sources of error

Besides the problem of the lacking disk space, the most frequent problem is that the VGA-Signal has to be pending at the VGA2USB BEFORE the start of the recording. After the start it is not allowed to change the resolution!

Without a pending VGA-Signal the recording can’t be started.