Unable to create UDP Stream, HTTP works fine

[Vamp898]

Hi there,

for TRPG Sessions, i want VLC to stream the music for the party and i first tried HTTP, but when the streams for quite some time, the delay gets unusable. When i switch the song, it could take up to 2 minutes when its 1 hour into the game.

I use the following command

Code: Select all

cvlc --repeat -I http --http-password XXX test.mp3 --sout-keep --sout='#standard{access=http,mux=ts,dst=0.0.0.0:8081}'

Works like a charm. But now i try the same with udp

Code: Select all

cvlc --repeat -I http --http-password XXX test.mp3 --sout-keep --sout='#standard{access=udp,mux=ts,dst=0.0.0.0:8081}'

I can see in netstat, that VLC doesn't open up an port. When i look into the logs, i just see a bunch of these

udp access out warning: send error: Connection refused

This also happens, when i run VLC as root. The firewall is open on that port and i also tried other ports

-A INPUT -p tcp -m tcp --dport 8081 -j ACCEPT
-A INPUT -p udp -m udp --dport 8081 -j ACCEPT

I also tried various variants of this command (RTP)

Code: Select all

cvlc -v --repeat -I http --http-password XXX test.mp3 --sout-keep --sout='#rtp{port=8081,dst=0.0.0.0}'

I don't get any error using that, but there is also no open port in netstat and clients are, obviously, unable to connect. So even though there is no error (even with -vvv), it just does nothing and i have no idea why. I tried using different ports or the IP of the server instead of 0.0.0.0 and again root, but nothing. It just streams the file into an unknown void.

Here is the -vv log, which is explicitly saying it connects to the port (even though, nothing is there)

[00007f4ff401e2c0] main stream output debug: using sout chain=`rtp{port=8081,dst=0.0.0.0}'
[00007f4ff401e2c0] main stream output debug: stream=`rtp'
[00007f4ff4022a10] main stream out debug: looking for sout stream module matching "rtp": 20 candidates
[00007f4ff4022a10] main stream out debug: set config option: sout-rtp-port to 8081
[00007f4ff4022a10] main stream out debug: set config option: sout-rtp-dst to 0.0.0.0
[00007f4ff4022a10] main stream out debug: using sout stream module "stream_out_rtp"
[00007f4ff402bed0] main stream debug: creating access: file:///srv/http/pub/vamp898/trpg/MOMBGM01.mp3
[00007f4ff402bed0] main stream debug: (path: /srv/http/pub/vamp898/trpg/MOMBGM01.mp3)
[00007f4ff402bed0] main stream debug: looking for access module matching "file": 26 candidates
[00007f4ff402bed0] main stream debug: using access module "filesystem"
[00007f4ff402d4a0] main stream debug: looking for stream_filter module matching "prefetch,cache_read": 26 candidates
[00007f4ff402d4a0] cache_read stream debug: Using stream method for AStream*
[00007f4ff402d4a0] cache_read stream debug: starting pre-buffering
[00007f4ff402d4a0] cache_read stream debug: received first data after 0 ms
[00007f4ff402d4a0] cache_read stream debug: pre-buffering done 1024 bytes in 0s - 28571 KiB/s
[00007f4ff402d4a0] main stream debug: using stream_filter module "cache_read"
[00007f4ff402e910] main stream debug: looking for stream_filter module matching "any": 26 candidates
[00007f4ff402e910] main stream debug: no stream_filter modules matched
[00007f4ff4c49fe0] main stream_directory debug: looking for stream_directory module matching "any": 1 candidates
[00007f4ff4c49fe0] main stream_directory debug: no stream_directory modules matched
[00007f4ff402e910] main stream debug: looking for stream_filter module matching "record": 26 candidates
[00007f4ff402e910] main stream debug: using stream_filter module "record"
[00007f4ff401e2c0] main stream output debug: adding a new sout input for `mpga` (sout_input: 0x7f4ffcc524a0)
[00007f4ff4022a10] stream_out_rtp stream out debug: maximum RTP packet size: 1400 bytes
[00007f4ff4022a10] main stream out debug: net: connecting to [0.0.0.0]:8081

[Rémi Denis-Courmont]

Connection refused on sending UDP means inbound ICMP errors, so either invalid parameters or network error. In this case, 0.0.0.0 is probably not considered a valid destination by your IP stack.

[Vamp898]

Connection refused on sending UDP means inbound ICMP errors, so either invalid parameters or network error. In this case, 0.0.0.0 is probably not considered a valid destination by your IP stack.

Thank you very much for your fast reply.

I enabled ICMP and checked if pinging works from inside the machine

$ ping 37.252.120.146
PING 37.252.120.146 (37.252.120.146) 56(84) bytes of data.
64 bytes from 37.252.120.146: icmp_seq=1 ttl=64 time=0.049 ms
64 bytes from 37.252.120.146: icmp_seq=2 ttl=64 time=0.072 ms
64 bytes from 37.252.120.146: icmp_seq=3 ttl=64 time=0.076 ms
64 bytes from 37.252.120.146: icmp_seq=4 ttl=64 time=0.073 ms
64 bytes from 37.252.120.146: icmp_seq=5 ttl=64 time=0.066 ms

As well as from an external host

>ping 37.252.120.146

37.252.120.146 に ping を送信しています 32 バイトのデータ:
37.252.120.146 からの応答: バイト数 =32 時間 =359ms TTL=39
37.252.120.146 からの応答: バイト数 =32 時間 =371ms TTL=39
37.252.120.146 からの応答: バイト数 =32 時間 =312ms TTL=39
37.252.120.146 からの応答: バイト数 =32 時間 =391ms TTL=39

I then tried using the external IP of the server instead of 0.0.0.0

cvlc -v --repeat -I http --http-password XXX MOMBGM01.mp3 --sout-keep --sout='#standard{access=udp,mux=ts,dst=37.252.120.146:8081}'

But the error keeps the same. There is no open port visible in netstat and the console continously spams this error message

[000055c98e219410] [http] lua interface: Lua HTTP interface
[00007f843c0184f0] udp access out warning: send error: Connection refused
[00007f843c0184f0] udp access out warning: send error: Connection refused
[00007f843c0184f0] udp access out warning: send error: Connection refused
[00007f843c0184f0] udp access out warning: send error: Connection refused
[00007f843c0184f0] udp access out warning: send error: Connection refused
[00007f843c0184f0] udp access out warning: send error: Connection refused
[00007f843c0184f0] udp access out warning: send error: Connection refused
[...]

# netstat -tulpen | grep vlc
tcp 0 0 0.0.0.0:8080 0.0.0.0:* LISTEN 1006 2193853 239082/vlc
tcp6 0 0 :::8080 :::* LISTEN 1006 2193854 239082/vlc

[lucdig]

As far as I know, the dst for udp output must be a unicast or multicast address. If you set a unicast address, you should see, with a tcpdump, udp packets sent from your vlc to the unicast address. The same for multicast address, but if you don't have a well configured multicast distribution network, multicast packets can flow to all the devices in your lan, and the lan can be saturated by these packets, so, be careful