[vlc-devel] [RFC] #2106: RTP streaming confusing in Qt intf

Marian Ďurkovič md at bts.sk
Wed Sep 24 18:02:19 CEST 2008

On Wed, Sep 24, 2008 at 04:53:52PM +0200, Rémi Denis-Courmont wrote:
> On Wed, 24 Sep 2008 12:24:11 +0200, Marian Ďurkovič <md at bts.sk> wrote:
> >    could streaming people please comment on this ?
> If you really need to do _both_ UDP and RTP, maybe you should not use the
> UI anyway. If we separate the two tabs, people will pick UDP _always_ just
> because they "know" what it is. I have seen this happen quite a bunch of
> times.

That's probably solvable with correct labeling e.g. 
- UDP (Deprecated)

This way the user would be alerted that such option is not the right one.
BTW, using HTTP (i.e. TCP) for streaming is no good either, yet we have
this in the UI.

Moreover, the UDP port is now equal to RTP audio port, which means it
lands at (non-default) value of 1235 after a few clicks.

> As for TS-muxing vs port-muxing, the point is only true if we have more
> than one elementary stream. Also, they are some FOURCC which cannot be
> conveyed over TS. And we if enable TS by default, we run into the same risk
> as with UDP: that people will interpret "non TS" as a dangerous option,

I'd not say dangerous, but it opens a can of worms we should try to avoid.
One of them is inter-stream synchronization, where you end up with several
seconds of no video or no audio until live555 gets RTCP for both and
synchronizes all ESs properly. Furthermore, going via live555 means no clock
synchronization in VLC and thus buffer overruns/underruns after e.g. 2 hours
of playback. Another problem is IP muxed streams could not be saved just by
picking the data from network and writing them to file, which *is* the case
for TS... And there are others - after all TS is recognized production 
quality broadcast format for good reasons.
> In any case you should really export the SDP.

Such option is not available from the UI. You can only check SAP-announce
there, but no HTTP nor RTSP. No user will write his own SDP & attempt to put
it on some web server just to have his stream available. 

> Then, the live plugin can
> open port-muxed streams. No matter how you look at it, it's really a matter
> of user-specific use cases, which one is best. Given that the streaming
> output panel is way out of reach of users who don't know how to use it, I
> think there is no need point in enabling the TS by default.

I don't agree here. TS is better for a bunch of reasons, it was the default
in all past releases and should IMHO remain to be the default.

	With kind regards,


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