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

Philip Mucci mucci at cs.utk.edu
Wed Apr 6 17:27:10 CEST 2005


Hi Ben,

Great! Thanks for the tips. I had thought I could do this from something
I found in the Streaming FAQ. It says "Under windows" you can do this
with direct show.

% C:\Program Files\VideoLAN\VLC\vlc.exe -vvv -I rc --ttl 12 dshow://
vdev="VGA USB Camera" adev="USB Camera" size="640x480"
--sout=#std{mux=ts,access=udp,url=239.255.42.12}

This doesn't show any sign of transcoding...what gives?

Thanks again, going to try it right now.

Phil

P.S. Funny about the logitech issue, I can't find a single sign of
other's having the blue screen 0x7F error...which according to the
Windows FAQ is an illegal instruction trap.

On Wed, 2005-04-06 at 20:41, Benjamin Pracht wrote:
> On Wed, Apr 06, 2005, Philip Mucci wrote :
> > 
> > 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)?
> > 
> 
> You need to transcode the video : You cannot stream raw video (and,
> btw, your bandwith wouldn't be sufficient anyway). Provided your
> requirements, MPEG1 (with a 1-3 Mbit/s bandwidth) would certainly be a
> good choice here. You can use UDP or http as a transport (depending on
> the fact you want push or pull streaming). You can set the
> --sout-transcode-fps 15 option to save some CPU power and some bandwidth
> if your input is 15 fps.
> 
> -- 
> Benjamin Pracht

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