I have a setup with a wired client as video stream server.
I have one more client connected on wireless. This client is accessing the video using multicast address.
Now I've enabled IGMP snooping (feature from openWRT) on AP. How the video quality varies before and after IGMP snooping enabled?
I've one AP, in which if I enable IGMP snooping, I don't see any video quality improvement.
I know that the whole process of IGMP snooping (if WAP supports) will convert multicast traffic to unicast traffic. But can I expect the video quality to be improved if I enable IGMP snooping?
Mainly because there is no answer. Assuming that there are no network losses or delays that can't be compensated for through the error-correction in the video stream, the two will be identical.
Multicast traffic are simply packets with a destination IP in the 18.104.22.168/4 range, which means that these packets should be send to all devices on the network. Unicast traffic are simply packets with a destination IP of a single device, for example 192.168.1.103. Since only the destination is different and the contents of the packets identical, the quality should be identical. But since multicast traffic will end up everywhere in the network, for large topologies this can overload the network, leading to packet loss and hence lower quality. For home networks, this shouldn't be an issue and you should expect identical quality.
You are incorrect in thinking that igmp_snooping converts multicast traffic to unicast. Igmp_snooping does in fact not convert multicast traffic to unicast traffic. The traffic will still have a destination IP in the 22.214.171.124/4 range, and hence is still considered multicast traffic. What igmp_snooping does, is that it listens to (snoops on) igmp traffic and keeps track which devices are subscribed to particular multicast streams. It will then use this information to only send the multicast traffic to ports to which devices are connected that are subscribed to this stream.
Even though there will be no differences in video quality with igmp_snooping enabled/disabled, you should still keep it enabled if you are not running into any issues with it enabled. Simply because it will result in a lesser load on your network, and hence higher network performance for other devices.