Kubuntu VLC 1.0.2 Client No Longer Plays UDP Multicast

[bhden2007]

Using VLC 1.0.2 client on Kubuntu Karmic Koala no longer can view input UDP Multicast MPEG-2 streams. The command "vlc udp://10.249.1.6@232.19.254.246:13246" opens the vlc client, but no video. Here is the debug log:

main debug: processing request item udp://232.19.254.246:13246 node Playlist skip 0
main debug: resyncing on udp://232.19.254.246:13246
main debug: udp://232.19.254.246:13246 is at 0
main debug: starting new item
main debug: creating new input thread
main debug: Creating an input for 'udp://232.19.254.246:13246'
main debug: thread (input) created at priority 10 (input/input.c:230)
main debug: thread started
main debug: using timeshift granularity of 50 MBytes
main debug: using timeshift path '/tmp'
main debug: `udp://10.249.1.6@232.19.254.246:13246' gives access `udp' demux `' path `10.249.1.6@232.19.254.246:13246'
qt4 debug: IM: Setting an input
main debug: creating demux: access='udp' demux='' path='10.249.1.6@232.19.254.246:13246'
qt4 debug: Updating the geometry
qt4 debug: Updating the geometry
main debug: looking for access_demux module: 0 candidates
main debug: no access_demux module matched "udp"
main debug: TIMER module_need() : 17.295 ms - Total 17.295 ms / 1 intvls (Avg 17.295 ms)
main debug: creating access 'udp' path='10.249.1.6@232.19.254.246:13246'
main debug: looking for access module: 1 candidate
access_udp debug: opening server=10.249.1.6:0 local=232.19.254.246:13246
main debug: net: connecting to [10.249.1.6]:0 from [232.19.254.246]:13246
main debug: Multicast source group join request
main debug: using access module "access_udp"
main debug: TIMER module_need() : 0.918 ms - Total 0.918 ms / 1 intvls (Avg 0.918 ms)
main debug: Using AStream*Block
main debug: pre buffering



I know that the input stream is good, because on another machine (connected to same network), VLC can view it just fine. Also, I have verified (with tcpdump and wireshark) that the stream is getting to my pc. The network monitor also shows increased input BW on my eth0 interface when trying to play the stream.

Has anyone seen this issue before or know how to resolve it? It seems that the stream is getting lost between my IP stack and VLC.

[Rémi Denis-Courmont]

That is symptomatic of a firewall, a security framework, or more trivially a wrong port number.

[bhden2007]

I checked iptables on my PC, and it is disabled. I know the port number is correct because the same port/stream works on another PC connected to the same LAN. Also, tcpdump shows that I am using the correct port number. For some reason VLC is not getting the stream, even though tcpdump shows the stream coming in on eth0 (UDP port 13246).

[Rémi Denis-Courmont]

Then the source address is wrong. Look VLC does not receive any data from the IP stack, so at least one of the IP-related parameters has to be wrong...

[bhden2007]

No, if the source address was wrong, then I wouldn't get the stream to the PC.

Here is my vlc command line (no video):
vlc udp://10.249.1.6@232.19.254.246:13246

At the same time here is output from tcpdump:

10:52:02.541726 IP 10.249.1.6.0 > 232.19.254.246.13246: UDP, length 1316
10:52:02.541826 IP 10.249.1.6.0 > 232.19.254.246.13246: UDP, length 1316
10:52:02.542330 IP 10.249.1.6.0 > 232.19.254.246.13246: UDP, length 1316
10:52:02.542420 IP 10.249.1.6.0 > 232.19.254.246.13246: UDP, length 1316
10:52:02.542549 IP 10.249.1.6.0 > 232.19.254.246.13246: UDP, length 1316

As you can see the stream is getting to my PC with correct source ip, mcast ip, and port. However, VLC is not picking it up.

On another PC connected to the same switch, at the exact same time, I can play the same stream with " vlc udp://10.249.1.6@232.19.254.246:13246". This is really driving me nuts! ;-(

Thanks,

[Rémi Denis-Courmont]

Well.. UDP source port 0. I would hardly be surprised if your IP stack dropped such crap.

[bhden2007]

Source port 0 is not the problem, because other streams with source ports 6000 have the same problem. The problem only exits on Linux boxes. Windows does not have any problem with these streams ;-(

[flyowynd]

I've got the same issue and did some research.

It should be the following problem cause by new k/ubuntu release that avoid any multicast packet to get to the system even so you will be able to see them using wireshark.

Go in /etc/sysctl.d and edit the file 10-network.... something
In this file you should have to value set to 1 (ipv4.filter but not quite sure)
Change this value to 0 and reboot.

This should works fine

[Rémi Denis-Courmont]

AFAIK, RP filter is a problem if and only if you are multihomed and your routing table is not configured properly.

[bhden2007]

RP filter was the problem. I did what flyowynd suggested, and I can now view multicast streams again!!!

I am multi-homed, but I believe my routing table is correct:
224.0.0.0 0.0.0.0 240.0.0.0 U 0 0 0 eth0

This routing table entry points to eth0 which is the interface the multicast is on.

Thank you both for all the help!!!

[Rémi Denis-Courmont]

RP filter is about source addresses, not destinations. Multicast addresses are not source addresses