Viewing UDP stream in v3.0.1 doesn't work. In v2.2.6 it works fine.

[thejaquio]

I am using OBS Studio to output a UDP multicast stream to my building, and viewing with VLC. I can view the stream just fine with VLC version 2.2.6, but the stream won't play (or it plays with audio only) in version 3.0.1.

The stream settings are as follows:
Container: mpegts
Video encoder: libx264 at 512kbps
Audio encoder: aac at 128kbps
Output resolution: 852x480

I've seen a few others on this forum with the same problem. Any help about how to fix this or what to change would be greatly appreciated.

[chubinou]

Hello,

UDP mtu is limited in VLC 3.0 to 1316, you can set the packet size on OBS side by setting the address to "udp://1.2.3.4:4242?pkt_size=1316"

Though, I rather advise you, to use "rtp_mpegts" as a container on OBS side, and on VLC side to use rtp://@1.2.3.4:4242 rather than using raw UDP. Be sure to use an even port number.

[thejaquio]

Thank you. This solved my issue. This solution works on both the old and new versions of VLC, so it eliminates the rush to upgrade. Thanks again.

[Aeium]

Hello,

UDP mtu is limited in VLC 3.0 to 1316, you can set the packet size on OBS side by setting the address to "udp://1.2.3.4:4242?pkt_size=1316"

Though, I rather advise you, to use "rtp_mpegts" as a container on OBS side, and on VLC side to use rtp://@1.2.3.4:4242 rather than using raw UDP. Be sure to use an even port number.

Thank you!

Not only did you solve the problem I had, you pointed me to the problem I should have had and solved that too!

Amazing. Made my day.

[Fosfor]

UDP mtu is limited in VLC 3.0 to 1316

Is there any possibility to change the MTU limit on the VLC side? Or any other workaround other than changing the stream source? I'm trying to figure our why receiving of UDP multicast is not working here neither in latest 3.x, nor in dev 4.x, but works in 2.x. I'm not getting any UDP MTU errors, but it seems, that actual packets are above the limit (1514 according to Wireshark).

[chubinou]

@Fosfor: you can try to set the mtu using the --mtu option or in advanced pref > Input/Codec > Network Settings > MTU of the network interface

[Fosfor]

Thanks chubinou, but neither helped. I tried to set MTU=1600 (as I have in version 2.2.8 ), but nothing changed. I already have some debug info, so I'll try to put it together and open a new topic.

[Rémi Denis-Courmont]

The MTU must be adjusted on the sending side. The receiver is powerless to change packet size.

[Fosfor]

So the settings suggested by chubinou have no effect?