[streaming] How to change multicast port

[Rémi Denis-Courmont]

Le Monday 03 March 2008 18:27:08 Thomas Kernen, vous avez écrit :
> Which I think that considering the number of users out there using VLC
> would be a good idea. Then the issue would be solved and vendors could
> "register" the port in their IPTV/Video monitoring tools.

I am not sure what you are talking about...

For RTP streaming, there is already a standard port number pair: 5004-5005. 
Regardless of the fact that past VLC releases fail to use it, I don't see the 
point in doing a VLC specific registration.

VLC has traditionnally used UDP port 1234 for plain MPEG Transport Stream over 
UDP. As it happened, it would not have been difficult to use an ephemeral 
port - this was initially multicast, and the "0" bind port trick would not 
work. Certainly, having a registered port would have been better. However, I 
am afraid those folks that still use this "legacy" TS over raw UDP streaming 
will not want to change their port number. In fact, they might not even 
update VLC, and changing the default port number might discourage them from 
upgrading even more strongly...

The third case involves sending multiple RTP streams (without TS). In that 
case, we need an abitrary number of _even_ ports - something IANA explicitly 
refuses to deal with. And we cannot use dynamic ephemeral port numbers either 
for several reasons:
 - some people want static port numbers for firewalling (as you pointed out),
 - the "0" bind port trick cannot force an _even_ dynamic port number,
 - the "0" bind port trick does not work when sourcing multicast.

So hmm... I am wary of doing IANA registration at this point... ?

-- 
Rémi Denis-Courmont
http://www.remlab.net/