[vlc-devel] Streaming wizard issues

Rémi Denis-Courmont remi at remlab.net
Mon Nov 30 21:47:52 CET 2009

Le lundi 30 novembre 2009 22:27:14 Pierre Ynard, vous avez écrit :
> > At least for native RTP, you will need to convey the SDP in some way.
> > Using a file seems totally wrong in the context of the wizard. And
> > RTSP follows such a different setup model that it probably should not
> > be considered "RTP" (but a different category of its own). Hence you
> > are stuck with SAP anyhow.
> And SAP propagates poorly across the internet, so you're stuck with
> nothing... Also, we're not offering native RTP now.

Fair enough, it won't work if the peer is far. I was mostly concerned with LAN 
use cases - e.g. streaming to/from a Wifi node. I guess SAP does not make much 
sense by default if the destination is in a different subnet.

> > Well it definitely is not intended for others. Then again, I would argue
> > the "others" are the victims here. They get their SAP playlist cluttered
> > with unreachable streams.
> Then we don't want to use SAP in those cases. You will notice that this
> depends on the presence or absence of other people to bother on the
> network, i.e. more generally, on the context (e.g. home network).

But how do you convey the SDP? For RTP/AVP, we need it, and SAP is pretty much 
the only way to deliver it; RTSP wouldn't even work for an hard-coded unicast 

I would rather avoid unusable defaults...

> > > What about replacing it with a "public/private stream" checkbox?
> > > This could handle TTL too, and maybe other options.
> >
> > No. Multicast privacy is achieved through ciphering, not through low
> > TTL.
> Call it discretion then. But my idea was also whether the stream is
> of "public" interest and intended to be broadcast to the whole internet,
> or something "private" just for your friends within your subnet.

To reiterate, if you want stealth mode, you should use encryption. But that 
will need changes on both sides. We cannot set Secure RTP nor -crappy- MPEG 
CSA keys with the open dialog currently.

That's beyond the scope of this thread.

Rémi Denis-Courmont

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