On 7 Apr 2009, at 06:34, Ross Finlayson wrote:
Basically, I've got an off the shelf TV encoder that broadcasts
MPEG2-TS onto the network. I used testRelay to read the source
address and relay it to another address. I've got VLC running on
another box on the same LAN with two play list items, one pointing
to the original broadcast address and the other to the relayed
address. Original plays fine, relayed one is corrupted badly with
lots of "libdvbpsi error (PSI decoder): TS discontinuity (received
14, expected 12) for PID 17" type messages appearing in the logs.
I suspect you're seeing network packet loss. See
http://www.live555.com/liveMedia/faq.html#packet-loss
This was the port problem Ross. I changed the code to receive on port
5000 and rebroadcast on 5001 and it's working perfectly.
Going forward with this little test app of mine, I need to be able to
receive different UDP streams on the same machine. Unfortunately, all
these streams will be on the same port. The encoder boxes in question
will let you choose different multicast base addresses and ports, but
the generated multicast addresses for each stream, while different,
will always be on the same port.
As has been mentioned a few times in the archives, by default the
GroupsockHelper code binds to the INADDR_ANY setting
(ReceivingInterfaceAddr is defaulting to this). What I need to happen
is that it should bind to the multicast address but join the group
using the wildcard interface, INADDR_ANY. This will allow the UDP
layer to filter correctly to the socket the datagrams for the addr/
port combination as opposed to app getting all datagrams for the port.
I've changed the code in GroupsockHelper::socketJoinGroup so that when
setting up the socket to join with IP_ADD_MEMBERSHIP we use INADDR_ANY
for the imr.imr_interface.s_addr value as opposed to using the value
in the ReceivingInterfaceAddr variable. This allows me to set
ReceivingInterfaceAddr in the testRelay.cpp code to the multicast addr
for correct binding while allowing the system to join the multicast
group on any interface.
What's your take on how this should be achieved ?
--
Glen Gray
sla...@slaine.org
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