NX client and remote video input devices

NX client and remote video input devices

[John A. Sullivan III]

Hello, all.  We are planning to launch a business to provide linux
based, virtual desktops and office environments to small business using
NoMachine's  NX technology.  One of the difficult issues we are facing
is video input especially for those wishing to use video over IP.  We
would like to use NX's native abilities rather than trying to manage a
second data stream for video via ssh or netcat and we are not even sure
such an arrangement would give us the control we would want over the
input device.

The basic set up is an end user at a physical desktop with a web cam
viewing a virtual desktop and needing to see the input of the web cam on
the virtual desktop as well as being able to control the input device,
e.g., start, stop, pause.  Something like this using mplayer as a
typical application:


            user                                   mplayer
              |                                        |
CAM______physical desktop-----------------------virtual desktop
             |                                          |
             |                                          |
          NXClient----------SMB share----------------NXServer

The SMB share is something NX supports natively.  We noticed we could
create a symbolic link to /dev/video0 and use this link to manage the
video input device.  However, when we try to mount this symbolic link as
an SMB share, we get an initial blinking light on our Logitech web cam
but then receive an error.  Here is the result of trying to use mplayer
to control the web cam input:

jsullivan@denisedell:~$ mplayer -fps 15 tv:// -tv
driver=v4l2:width=640:height=480:device=/home/jsullivan/MyShares/NXSHARES/video0
MPlayer 1.0rc2-4.2.3 (C) 2000-2007 MPlayer Team
CPU: Intel(R) Pentium(R) 4 CPU 2.80GHz (Family: 15, Model: 3, Stepping:
4)
CPUflags:  MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 1 SSE2: 1
Compiled with runtime CPU detection.
mplayer: could not connect to socket
mplayer: No such file or directory
Failed to open LIRC support. You will not be able to use your remote
control.

Playing tv://.
TV file format detected.
Selected driver: v4l2
 name: Video 4 Linux 2 input
 author: Martin Olschewski <olschewski@zpr.uni-koeln.de>
 comment: first try, more to come ;-)
v4l2: ioctl query capabilities failed: Inappropriate ioctl for device
v4l2: ioctl set mute failed: Inappropriate ioctl for device
v4l2: 0 frames successfully processed, 0 frames dropped.


Exiting... (End of file)

How can we control and access a video input device on a remote computer?
This is a high priority project for us (our first potential customer) so
any help would be greatly appreciated.  Thanks - John
-- 
John A. Sullivan III
Open Source Development Corporation
+1 207-985-7880
jsullivan@opensourcedevel.com

http://www.spiritualoutreach.com
Making Christianity intelligible to secular society


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Re: NX client and remote video input devices

[Alan Cox]

On Mon, Jun 02, 2008 at 11:37:14AM -0400, John A. Sullivan III wrote:
> The SMB share is something NX supports natively.  We noticed we could
> create a symbolic link to /dev/video0 and use this link to manage the

SMB can't export devices, let alone manage a distributed mmap interface

> How can we control and access a video input device on a remote computer?
> This is a high priority project for us (our first potential customer) so
> any help would be greatly appreciated.  Thanks - John

You need some kind of video library in the middle. Look at something like
gstreamer or videolan would be my first thoughts. A lot of video apps already
use gstreamer as their video framework and it means compression and processing
can occur before you burn network bandwidth.

Alan

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Re: NX client and remote video input devices

[John A. Sullivan III]

On Mon, 2008-06-02 at 11:58 -0400, Alan Cox wrote:
> On Mon, Jun 02, 2008 at 11:37:14AM -0400, John A. Sullivan III wrote:
> > The SMB share is something NX supports natively.  We noticed we could
> > create a symbolic link to /dev/video0 and use this link to manage the
> 
> SMB can't export devices, let alone manage a distributed mmap interface
> 
> > How can we control and access a video input device on a remote computer?
> > This is a high priority project for us (our first potential customer) so
> > any help would be greatly appreciated.  Thanks - John
> 
> You need some kind of video library in the middle. Look at something like
> gstreamer or videolan would be my first thoughts. A lot of video apps already
> use gstreamer as their video framework and it means compression and processing
> can occur before you burn network bandwidth.
> 
> Alan
> 
Thank you very much.  I'm still on a steep learning curve for video and
so don't know much about either especially in a KDE environment.  I'll
put in the research time and see what I find! Thanks again - John
-- 
John A. Sullivan III
Open Source Development Corporation
+1 207-985-7880
jsullivan@opensourcedevel.com

http://www.spiritualoutreach.com
Making Christianity intelligible to secular society

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