[vlc-devel] Re: vlc: svn commit r13006 (fkuehne)

Marian Durkovic md at bts.sk
Tue Nov 1 09:42:38 CET 2005

Hi Viktor,

On Mon, Oct 31, 2005 at 12:39:32PM +0200, Viktor Kompaneyets wrote:
> A lot of my devices (linux boxes) use raw UDP and non-RTP udp protocols.

Could you perhaps give some more information, e.g. what are those devices - 
PCs or special devices (set-top-boxes) running Linux OS? What application
are you using for receiving the raw UDP streams? Do you have source code
of this aplication?

> Disabling raw UDP will switch me from VLC completely or making an 
> transforming  from RTP to raw UDP. 

Noone has proposed to disable raw UDP. Raw UDP is, and will be available 
from Open->StreamOutput Window as well as from command line.

This discussion was only about StreamingWizard i.e. the part of VLC aimed to
assist users to pick the best choices suitable for most of them. RTP is 
certainly better than raw UDP (see my previous emails). Even in case of simple
LAN where no reordering happens, RTP is better for at least two reasons: 

1) it exactly identifies the payload. With raw UDP, only intelligent guesswork
could be used to estimate the payload type and at least with some streams 
this is not 100% safe (sometimes MPEG-TS from Vbricks is misdetected as 
being MPEG-PS). Such exact identification could also assist to properly set
quality-of-service parameters in the network.

2) RTP continuously checks the packet sequence numbers, and if some packet(s)
are dropped in the network, it's able to inform the user and tell him how 
many packets are missing. This helps to separate network problems from others.

> > - and most VLC users are aware of the 
> > need for RTP, even if they incorrectly announce their session as being
> > raw UDP - but I've fixed this in [12899] so this should disappear as soon
> > as they upgrade to 0.8.4.
> Don't do so!

You've probably misunderstood this paragraph. Before [12899], VLC announced
raw UDP streams as "raw UDP", but also RTP streams as "raw UDP". This was
only working for VLC due to RTP autodetection, but other standard's based
applications  were confused and unable to play such RTP streams. In [12899] 
I've fixed this problem, so now raw UDP streams are announced as "raw UDP" 
and RTP streams are correctly announced as "RTP".

	With kind regards,


----                                                                  ----
----   Marian Durkovic                       network  manager         ----
----                                                                  ----
----   Slovak Technical University           Tel: +421 2 524 51 301   ----
----   Computer Centre, Nam. Slobody 17      Fax: +421 2 524 94 351   ----
----   812 43 Bratislava, Slovak Republic    E-mail/sip: md at bts.sk    ----
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