Java Media Framework always generating multicast packets with TTL=1

Question

I need to generate a G711 multicast audio stream, and came across the AVTransmit2 sample as part of the Java Media Framework.

Fundementally this works, however the multicast packets all have TTL set to 1.

I found some documentation that suggested the SessionAddress could specify a TTL value, so I've tried changing that i.e. destAddr = new SessionAddress( ipAddr, port, 255);

I also found some comments that the problems might be due to java defaulting to IPv6, so I've tried to force it to ipv4 by starting it like this: java -Djava.net.preferIPv4Stack=true -classpath "." AVTransmit2 javasound://8000 239.1.10.65 20480

However looking in wireshark, the packets still have TTL=1

I'm using JMF2.1.1e

Any suggestions how to resolve this?