[vlc-devel] Re: vlc streaming / udp multicast performance

[Mark Moriarty]

I really do believe it's something peculiar to your setup, though not sure
what.  When I'm doing system checks I do 24 hour runs, multicasting CCTV to
a mix of clients, both on the local 10/100 switch and connected through a
pair of routers via a T1 (1.544 Mbps) WAN connection.

A successful (consistent good quality) VLC TX is obtained, in Windows, with:
vlc dshow:// :dshow-vdev="Osprey-210 Video Device 1" :dshow-adev="none"
:no-dshow-config :dshow-size="640x480"
:sout=#transcode{vcodec=mp4v,vb=756,scale=1}:duplicate{dst=std{access=udp,mu
x=ts,url=239.20.30.40:1234}}

If I just wanted to TX a file, I would use:
Vlc whatever.mpg
:sout=#duplicate{dst=std{access=udp,mux=ts,url=239.20.30.40:1234}}

And  clients would use:
Vlc udp://@239.20.30.40:1234  

-----Original Message-----
From: vlc-devel-bounce at videolan.org [mailto:vlc-devel-bounce at videolan.org]
On Behalf Of Marius Kjeldahl
Sent: Wednesday, December 29, 2004 9:00 PM
To: vlc-devel at videolan.org
Subject: [vlc-devel] Re: vlc streaming / udp multicast performance

Mark Moriarty wrote:

 > Not sure, but things may be confused due to your address selection:
 > 224.0.1.0 - 224.0.1.255  (224.0.1/24) Internetwork Control Block

Trying a couple of the suggested range of addresses (I tested with
239.192.0.1 and 239.0.0.1) did not change anything; I still see the video,
but with lots of noise and green squares (I guess this indicates a lot of
data is not getting through).

Måns Rullgård wrote:

 > Are you by any chance using a wireless LAN?  Multicast and WLANs do  >
not always play well, and may need special tuning of the access points  > to
work at all.
 >
 > The obvious question: have you tried other clients and/or other  >
servers?

Well, I have a wireless LAN I have tested with as well, but everything is
tested outside of the wireless LAN first. My wlan is on a different subnet.
Same symptoms on the WLAN - if I do not use multicast, even the WLAN
connected computer more or less displays the video more or less fine (well,
some noise and/or packet loss but very little compared to what I get when
using multicast). But everything is tested on a 100mbit ethernet as well
(both server and client on the same switch), and the results are more or
less the same. I know from experience that the WLAN has less bandwidth, but
a stream directly to the wlan connected computer looks crystal clear
compared to a multicast on the cabled subnet.

Regarding clients; I've tested with xine on a linux computer, and it
receives data but spends most of it's time buffering (guess it has
aggressive buffering by default). But I can still see bits and pieces of the
multicasted video inbetween. Mplayer does not seem to support the "raw" udp
stream.

Regarding servers; care to mention any that is available free of charge on
linux? I haven't found any...

Ted Deppner wrote:

 > where's the @?  should be vlc udp:@224.0.1.1:1234.  As the other  >
poster said, some 224.0. stuff is reserved... try 225.0.1.1.

You are right. Forgot it when posting here, but had it in when testing.

Thanks,

Marius K.

Marius Kjeldahl wrote:
> I've done some testing using vlc for streaming a local file over my 
> network using the --sout parameter from the command line. If I stream 
> "point to point" over udp with the following setup:
> 
> Server: vlc --sout udp:192.168.0.10:1234 somefile.mpg
> Client: vlc udp:192.168.0.10:1234
> 
> the client displays the video just fine. However as soon as I try to 
> use multicast with the following setup:
> 
> Server: vlc --sout udp:224.0.1.1:1234 somefile.mpg
> Client: vlc udp:224.0.1.1:1234
> 
> the client only gets a fraction of the packets/bandwidth, and very 
> little of the video and sounds gets through. Although I'm pretty new 
> to this multicast stuff, I believe I set up the multicast more or less 
> correctly on linux, using:
> 
> $ ip route add -net 224.0.0.0 netmask 240.0.0.0 dev eth0
> 
> To try to rule out possible mistakes at my end, I've tested this 
> across a couple of different machines in my network and across linux 
> and windows. Even when I stream from windows to another linux machine, 
> I get the same behavour with multicast (very poor performance, seems 
> packet loss is big).
> 
> Does anybody know if these issues are related to vlc itself, or should 
> I keep looking elsewhere?
> 
> Thanks,
> 
> Marius K.
> 

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