[FFmpeg-user] is filtering 3 multicast addresses using same port possible?

[robb]

hello,
i'm trying to ingest 3 multicast streams using the same port.
i can change the the multicast addresses (239.255.x.x) but not the ports
i can also change the group #s

i read on the FFmpeg Protocols Documentation page under udp that:

sources=address[,address]Only receive packets sent from the specified
addresses. In case of multicast, also subscribe to multicast traffic coming
from these addresses only.
*block=address[,address]*
Ignore packets sent from the specified addresses. In case of multicast,
also exclude the source addresses in the multicast subscription.

however, the following doesn't seem to work & i'm not able to find others
with the same kind of port problem

ffmpeg -i udp://192.168.1.2:5004*?sources=239.255.42.42* -vcodec copy
-codec:a aac -b:a 128k -f flv out.flv

am i missing something in the syntax or address assignment?

thx for all the bits :)