[vlc-devel] Streaming wizard issues

Rémi Denis-Courmont remi at remlab.net
Mon Nov 30 12:56:46 CET 2009

On Mon, 30 Nov 2009 12:19:22 +0100, Marian Ďurkovič <md at bts.sk> wrote:
>> > Everyone uses udp in the URLs, so the main title should say UDP, maybe
>> > a smaller explanation somewhere in the tab saying we're packing it
>> > into MPEG-TS will be useful. Same for RTP. 
>> The point is that I have witnessed quite a lot of confused users with
>> this.
>> If you're saying "screw them", I cannot agree. And if you're saying let
>> them use raw UDP when they could do RTP, I cannot agree either.
> I haven't said any of the above. In fact, I was among the first people on
> this list urging anyone to use RTP instead of UDP.

I know. But leaving "UDP" as is just pushes people in the wrong direction.
It really is MPEG-TS over UDP (vs MPEG-TS over RTP over UDP vs native RTP
over UDP).

>> You can always turn SAP off. Universities with multicast are not the
>> "benchmark" for the wizard; IMHO, the default should be aimed at the
>> majority.
> I don't agree here. Commercial ISPs typically also don't have IPv6, yet
> it's no argument to adopt incorrect solutions for it. Having said that,
> we *must* be aware, that announcing something via SAP might result in
> global visibility, and we shouldn't invade users' privacy by making
> global announcement behind the scenes.

Well, VLC does automatically scope SAP announces according to the scope of
the multicast group, so this would normally be a non-issue. Unfortunately,
IPv4 SSM is not scoped to my knowledge.

>> > No. We don't know whether the user wants to use global ASM group, GLOP
>> > or some of the local group addresses.
>> And then what? If you want to do something else, you can always change
>> the group address. Putting a default has many advantages:
> ... and also some disadvantages, e.g. a randomly generated address
> each time VLC is run. This is major annoyance as it basically excludes
> the possibility for manually opening the stream without automated
> assistance (RTSP/SAP,etc).

I don't see that. I never meant to remove the field (though we did have an
option for that in the UDP output at some point), just to file a default
value automatically.

> It's error-prone for users which want to use a specific
> group, since the wizard suceeds even if the user forgot to specify the
> group.

I think it's actually less error-prone than no value at all.

> There are different views regarding the defaults, for example, even the
> default RTP port is typically not supported in STBs or some other
> mplayer rtp://
> Playing rtp://
> STREAM_RTP, URL: rtp://
> You must enter a port number for RTP streams!

To me, that just looks like a good reason to use SAP by default...

Rémi Denis-Courmont

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