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

Marian Durkovic md at bts.sk
Tue Nov 1 17:00:55 CET 2005

On Tue, Nov 01, 2005 at 11:35:24AM +0200, Viktor Kompaneyets wrote:
> > What 
> > application are you using for receiving the raw UDP streams? Do you have
> > source code of this aplication?
> Yes, I have. I had _removed_ RTP from them to achive better wandwith
> consumtion (with RTP it is not enough!)

Well, VLC puts 7 TS packets into one UDP frame - this is 1316 bytes. UDP
header is 8 bytes, IPv4 header 20 bytes. So alltogether it's 1344 bytes.

With RTP you'll only need additional 12 bytes - i.e. the frame grows to 
1356 bytes in total. The difference is less than 0.9 %.

In other words, if you're streaming at e.g. 512 kbit/s, with RTP you'll 
need no more than 516.6 kbit/s. Does this really matter for your setup ?

> > 1) it exactly identifies the payload. 
> I know exactly a payload of stream - so no need to make SDP.
> > 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 
> No need - streams are hard defined.
> > (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.
> No need in my setup.

Well I do understand that with hard defined values and very restricted
environment these might not be needed. But such solution is limited to your
special environment and can't work in a more general cases. Also one day you
might need to support some additional formats... My position here is that
compliance with RFC standards is _always_ good thing and since the bandwidth
overhead is really negligible, it's generally not worth breaking the
standards. If your environment needs special handling - fine, but still VLC
is IMHO positioned as a player for broad range of different environments
and therefore should promote standards compliance instead of breaking them.

	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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