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

Marius Kjeldahl marius at kjeldahl.net
Thu Dec 30 03:00:09 CET 2004

Mark Moriarty wrote:

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

Trying a couple of the suggested range of addresses (I tested with and 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:@  As the other
 > poster said, some 224.0. stuff is reserved... try

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


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: somefile.mpg
> Client: vlc udp:
> the client displays the video just fine. However as soon as I try to use 
> multicast with the following setup:
> Server: vlc --sout udp: somefile.mpg
> Client: vlc udp:
> 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 netmask 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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