[streaming] How to change multicast port

[Thomas Kernen]

Rémi Denis-Courmont wrote:
> 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... ?
> 

Admit that I was looking at it purely from the MPEG-2 TS point of view 
and ignoring multiple RTP (non MPEG2TS) streams. My experience with 
people running VLC as an IP streamer is that due to the fact that there 
is no "standardised" port the network operations people tend to complain 
that their monitoring equipment doesn't "detect" VLC sources out of the box.

So agreed that 1234 is well known, but as Marshall mentioned, registered 
to another application. That 5004-5005 are registered, but that isn't 
the default and I believe that documentation doesn't highlight this.

So maybe something better in the README/documentation could be a soft 
start to this.

Thomas