Re: Fatal Errors with Windows version

M. Carleer (mcarleer@ulb.ac.be)
Wed, 28 Jun 1995 18:26:46 +0100


Jim wrote:

>I continually get "Unable to find a free Video Context entry. Fatal
>Error" message while connected to pv70f2.vincent.iastate.edu trying to
>view NASA TV. I get this error with both W0.65b1 and the older
>W0.34b6.
>
I also got this while connecting to any NASA reflector yesterday, but not
anymore. Something to do with the sender or the reflector?

>Also, I do not have a sound card and have a .WAV driver installed to
>run the PC's speaker. According to File/Sound devices, the Playback
>device "Sound Driver for PC-Speaker" is configured, but I don't seem
>to be getting any sound. When I select Conference/Start receiving
>sound, I am told "Sorry, an unknown error, 35, has occurred while
>attempting to open the wave output device, but when I select
>Help/About I hear the "Star Trek door sound" before the dialog comes
>up. Any Ideas??
>
>
Jim, the problem is that the amplifier of the PC's speaker only produces two
levels: on or off (+5V or 0V). To reproduce sound, the PC's speaker driver
has to send a frequency high enough that it will be smoothed out by the low
pass filter, but with an on/off ratio that will hopefully give some
intermediate value between 0 and +5V. This means that the CPU has to
constantly adjust this on/off ratio during the playback of sound. It is
therefore unable to do anything else during that time and this is of course
incompatible with the reception of the sound (or the video) from the net.
That's why the use of the PC's speaker with CUSeeMe is impossible. Of course
you can hear the "Door Sound" when selecting About, but then all
transmission from/to CUSeeMe is suspended. You really need a sound card to
get sound with CUSeeMe, sorry about that. It is true however that given all
this, the PC's speaker driver should not appear as a possible choice in the
Playback device dialog control. Rich, sorry, mea culpa.

Cheers,
Michel
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Michel Carleer

Laboratoire de Chimie Physique Moleculaire Phone : +32-2-650.24.25
Universite Libre de Bruxelles CPi-160/09 Fax : +32-2-650.42.32
50 Av F.D. Roosevelt e-mail: mcarleer@ulb.ac.be
B-1050 Bruxelles
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