[vlc] Re: Crash on 3 different systems: Logitech's fault, now how tostream a RAW webcam feed?

[Moriarty, Mark F]

UDP is the way to go, normally, multicast if your wireless will pass it.
Mp4v video coding does well.

On a 3GHz Pentium IV I run about 20% CPU transcoding to mp4v, 640x380,
30 fps.  This stuff is pretty linear in terms of number of pixels x
frame rate / CPU speed, so if you run 15 fps it would take 10% on a 3
GHz, or about 30% on a 1 GHz, ballpark. 

vlc dshow:// :dshow-vdev="CompUSA PC Camera" :dshow-adev="none"
:no-dshow-config :dshow-size="640x480"
:sout=#transcode{vcodec=mp4v,vb=1024,scale=1}:duplicate{dst=std{access=u
dp,mux=ts,url=239.20.30.40:1234}} --sout-transcode-fps 15

Is a sample.  It multicasts 640x480, with an explicit output fps of 15
(even if the input is 30, this would limit the output, the video being
encoded to mp4v, to 15 fps).

If you also have audio (probable), you would use something like:
vlc dshow:// :dshow-vdev="CompUSA PC Camera"
:dshow-adev="Audio_Device_Name" :no-dshow-config :dshow-size="640x480"
:sout=#transcode{vcodec=mp4v,vb=1024,scale=1,acodec=192,ab=192,channels=
2}:duplicate{dst=std{access=udp,mux=ts,url=239.20.30.40:1234}}
--sout-transcode-fps 15

To receive the above, a client would use a one-line batch program
consisting of:
Vlc udp://@239.20.30.40 

To get the values for "CompUSA PC Camera", and "Audio_Device_Name", you
use what appears when you do the Refresh, the things you select.
Alternately, you can go in through Settings -- Preferences, make them
the defaults.  (I prefer to explicitly include things in the command
line, makes it less ambiguous)

Where are you working?  Khumbu/Solo-Khumbu, or down in the jungle?  Just
curious -- I've been there a few times, mountain trekking.

-----Original Message-----
From: vlc-bounce at videolan.org [mailto:vlc-bounce at videolan.org] On Behalf
Of Philip Mucci
Sent: Wednesday, April 06, 2005 10:04 AM
To: vlc at videolan.org
Subject: [vlc] Re: Crash on 3 different systems: Logitech's fault, now
how tostream a RAW webcam feed?

Hi folks,

Thanks for the replies. Indeed, it's logitech's crappy software. Even
though I have the latest service packs, directX and Logitech driver, the
logitech driver can be crashed easily by simply right clicking on the
quick cam in the system tray and going to "Camera Settings", then
clicking "Driver Settings" button. Boom, crashola. Thanks Logitech.

I am able to get by this by opening the "Camera Settings" from the
system tray and then clicking the "Default Settings" button. This seems
to put the camera in a saner state and I can, IF I enable dshow-config
with the device properties tab, get VLC to play nice.

So, now that we've identified the cause, on to the next issue!

We have a local wireless lan, with pretty good bandwidth. The camera is
a USB-1 camera with a 640x480 sensor...which means the best we can do is
15 frames per second. Since we are displaying the blackboard as well as
the teacher, we want the highest quality video possible. We can eat all
of the LAN bandwidth if necessary. And the load on the CPU should be as
little as possible because we'll be lucky if we get Pentium III's out in
the bush.

Can someone recommend the best way to stream 640x480 video from a web
cam over UDP or HTTP? Is it possible without transcoding?
Selecting RAW and no transcoding initiates a connection, but nothing
displays. Messages on the client just say "garbage at input". If I need
transcoding, what combo should give me the highest quality, lowest CPU
requirement (with highest network bw ok)?

Thanks for any and all help.

Namaste,

Philip
 


On Wed, 2005-04-06 at 07:27, Mark Moriarty wrote:
> On XP, if you have upgraded to SP2 it is critical to check for new 
> video drivers for whatever graphics chip the PCs have.
> 
> Have you tried doing an Open -- Open Capture Device, and just getting 
> a local display?  Make sure you plug in a valid value in the dshow 
> size area
> -- I would try 160x120 first, then maybe 320x240.
> 
> As long as the Webcam is DirectX compliant, it should work, if you do 
> have whatever logitech directshow drivers are available for the 
> device. A quick check indicates it's a basic USB camera -- correct?  
> There's a 2004 driver out there, should be OK.
> 
> 98SE could be tougher -- it's a bit iffy, you have to be really 
> careful on patches/drivers, based on threads I've seen.
> 
> Good luck -- it sounds like an excellent project!
> 
> -----Original Message-----
> From: vlc-bounce at videolan.org [mailto:vlc-bounce at videolan.org] On 
> Behalf
Of
> Philip Mucci
> Sent: Tuesday, April 05, 2005 12:18 PM
> To: vlc at videolan.org; mucci at cs.utk.edu
> Subject: [vlc] Crash on 3 different systems WinXP Home/Logitech 
> QuickcamExpress/VLC 0.8.1/0.7.2
> 
> Hi folks,
> 
> I'm at the end of my rope, I've scoured google, the faq, the forums 
> and
the
> mailing lists and haven't come up with anything.
> 
> I'm in the midst of working on a teleteaching project here in Nepal.
> (I'm a computer scientist donating some time, so you don't have to ask

> me
if
> the cable was plugged in. ;-)
> 
> For this project, we were hoping to use VideoLan with an array of 
> donated Logitech Quickcam Express and a variety of window's boxes (I'm

> a linux guy
> myself) running XP Home and 98SE. Videolan worked wonderfully on my
Thinkpad
> T23 with Logitech Notebook Pro 4000 back at the office, so I thought 
> this was going to be a piece of cake.
> 
> No such luck.
> 
> On every system XP Home system I have access to here, I can blue 
> screen
the
> system instantly by:
> 
> 1) Using the wizard to start an HTTP stream from the camera, basically
just
> click refresh on the video device, click logitech and continue from
there.
> 
> 2) Opening the capture device, repeat the refresh and click configure,
bomb.
> 
> 3) doing 2 but not clicking configure and just continuing.
> 
> So, I read on one of the mailing lists that everything should be the
latest
> and greatest, but is that really realistic for most of the world?
> Nevertheless, I downloaded the latest Direct X and Logitech drivers, 
> still crash city.
> 
> The message from bluescreen?
> STOP: 0x0000007F (0x00000000,0x00000000,0x00000000,0x00000000)
> 
> If anyone has any tips on this, they are greatly appreciated. I'm not
using
> this to send porn into my bedroom (not yet), I'm using this to bridge 
> the education gap in remote villages in nepal. Getting this working 
> really
makes
> a difference.
> 
> Thanks again,
> 
> Philip Mucci
> 
> www.nepalwireless.net
> www.himanchal.org
> www.cs.utk.edu/~mucci
> 
> 
> --
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