Subject: X-terminals & videoconferencing

From: Lukas Wunner <[email-masked]>
Date: Fri, 1 May 1998 17:11:34 +0200

Hi,

We would like to do videoconferencing with X-Terminals (e.g. NCD HMXpro24).
Displaying video images on an X-Terminal is obviously not an issue,
but grabbing video images using a camera attached to an X-Terminal and
sending/playing audio data with an X-Terminal seems to be, well, not
an easy task. The HMX terminals have a parallel port, so in theory it
*should* be possible to attach, say, a QuickCam, and grab images using
a local X11 client; similarly it is probably feasable to input/output
audio data using the audio hardware built-in to the terminal and by
patching vat to support NCD's Network Audio System.

If anyone can shed light on this issue (i.e., it can/cannot be done),
please drop me a line. Thanks!

	Lukas.

-- 
lukas wunner         unix, internetworking and security engineer
[email-masked]      LW26-RIPE      http://www.wunner.de/~lukas/
Funkmodems mit 2.4GHz FAQ      http://www.wunner.de/~lukas/funk/
     "Speak the words I wanna hear, to make my demons run."

---

From: Hugh LaMaster <[email-masked]>
Date: Fri, 1 May 1998 12:44:32 -0700 (PDT)

> patching vat to support NCD's Network Audio System.

An excellent question which, with the advent of NC's, I have
been wondering myself.  Does anyone out there know which 
X extensions exist already to satisfy some of these requirements,
which I consider perfectly valid, and which are being worked on
by, e.g., NCD (which developed the first netaudio for X terminals
I believe - does anyone still use that?), the Network Computer 
consortium, or whatever.

My assumptions going in to this would be: assume a high-speed
LAN and server, classical X terminal environment, NOT a WAN;
and, assume a high-performance server running a bunch of NC's.

Performance-wise, would this work?  How well did the NCD 
network audio work?  Is it still out there?  Did any apps
ever support it?

--
 Hugh LaMaster, M/S 233-21,    ASCII Email: [email-masked]
 NASA Ames Research Center     Or:          [email-masked]
 Moffett Field, CA 94035-1000  No Junkmail: USC 18 section 2701
 Phone: 650/604-1056           Disclaimer:  Unofficial, personal *opinion*.

---

From: Bill Fenner <[email-masked]>
Date: Sat, 2 May 1998 14:58:48 PDT

If we're talking about straight X-terminals, then network utilization
will be much higher than with normal multicast clients.  The server will
receive the multicasted audio, decode/decompress it and unicast it to
each X terminal that is listening to that particular session.  Similarly
with the video, except that video increases in size much more than
audio does (e.g. 2 frames/sec of 320x200 24-bit uncompressed video is
3Mbps; 30 frames/sec is 45Mbps).

  Bill

---

From: Amancio Hasty <[email-masked]>
Date: Sun, 03 May 1998 09:07:51 -0700

Hi Guys,

The X terminal folks should be able to develop the X protocol extensions
to support audio / video conferencing for mbone applications.

For instance, NCDs network audio can be modified to support audio
compression.

If an X terminal supports XIE then most likely it has enough cpu power 
to support H.261. For one of my clients, a few years ago we wrote an X 
server which supported hardware fax decompression/scaling/rotation using
XIE . Prior to my X server, application developers spent their time
in the labs after that we just had  rows of computers sitting in the lab
with their display redirected to the developers workstation . We needed to 
contained the image stations to their on lan due the network protocol
that we were using.

	Cheers,
	Amancio

---

From: "Jeff Young" <[email-masked]>
Date: Wed, 06 May 1998 22:11:35 -0400

i used to do this in the early days of the multicast video clients
to illustrate how easy it is to bring a shared ethernet to its knees.
it also makes a wonderful traffic source and provides instant feedback
about packet loss.  as long as the machines in question have fast 
enough video, set up a high bitrate video session from one machine
to another through a test network.  as long as you can see both 
machines, any glitch in the video on the xterminal gives real-time
feedback about packet loss.  :-).

Jeff Young
[email-masked]

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> To: Hugh LaMaster <[email-masked]>
> cc: [email-masked]
> Subject: Re: X-terminals & videoconferencing 
> In-reply-to: Your message of "Fri, 01 May 98 12:44:32 PDT."
>              <[email-masked]> 
> Date: Sat, 2 May 1998 14:58:48 PDT
> From: Bill Fenner <[email-masked]>
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