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

[Derk-Jan Hartman]

On 28-okt-2005, at 22:27, Marian Durkovic wrote:
> Hi Derek, Felix,
>
>    I really don't quite understand what's the problem here. In this  
> context,
> RTP is nothing else that UDP plus 12 bytes. But the huge difference  
> is, that
> it is standards based (RFC3550) and works properly over large networks
> (read Internet). It uses exactly the same payload format - MPEG2-TS.
> In this context, we don't speak about RTSP and/or separate audio/ 
> video RTP
> streams.

I'm perfectly aware what it is. It is "different" from UDP, not just  
UDP with something extra. that's like saying HTTP is just TCP. The  
view is too simplistic.

>    Could you please elaborate, what's the exact problem with  
> replacing UDP by
> RTP >>in streaming wizard<< ? I was under impression, that wizard  
> is a easy-to
> use tool, with limited choises (just UDP/HTTP) and my understanding  
> is that
> users should get the best possible alternative here for easy and  
> reliable
> streaming.

1: you didn't ask
2: UDP has much less overhead then RTP
3: RTP has undergone major changes. changes make something unstable  
and therefore making this default is DEFINITELY not something that  
should be done just before an 0.8.4 release
4: UDP is used a lot for various STB solutions
5: you didn't ask

>    If there's a real case for raw UDP (e.g. set-top-box getting  
> confused by
> those 12 extra bytes), this option is available via StreamOuput  
> dialog as
> well as via command line. Anyway I consider clients not capable of
> accepting RTP headers obsolete, since the RTP standard RFC1890 is  
> here for
> almost 10 years now. VLC/VLS sends/accepts RTP for 3 years - so now  
> when
> RTP reordering is available, I think it's the right time to make  
> RTP the
> defualt protocol and consider raw UDP special case only if needed.

Perhaps, but not right before an 0.8.4 release. (i have seen less  
significant changes that turned out to eventually require us to do a  
2nd'ary release to the original)

>    In any case, I'd suggest that RTP is at least added to the  
> Wizard, since
> it's far better than raw UDP and most users don't have a real need  
> for raw UDP.

That was the idea yes.

>    In case you wonder why I push RTP such much, please see the  
> following
> debug log for RTP stream from uoregon.edu to stuba.sk:
>
> access_udp debug: RTP reordering: insert after 26002, new 26003
> access_udp debug: RTP reordering: insert after 26009, new 26010
> access_udp debug: RTP reordering: insert after 26017, new 26018
> access_udp debug: RTP reordering: insert after 26027, new 26028
> access_udp debug: RTP reordering: insert after 26033, new 26034
> access_udp debug: RTP reordering: insert after 26037, new 26038
> access_udp debug: RTP reordering: insert after 26062, new 26063
> access_udp debug: RTP reordering: insert after 26064, new 26065
> access_udp debug: RTP reordering: insert after 26079, new 26080
> access_udp debug: RTP reordering: insert after 26092, new 26093
> access_udp debug: RTP reordering: insert after 26096, new 26097
>
>    As you can see, no packet was lost, but 11 out of 100 packets were
> reordered by the network. With raw UDP, you're lost - such stream is
> completely unwatchable. With RTP, there's no single error.

Your situation is one of many very diverse situations. ALL need to be  
taken into account.

DJ

>
> On Fri, Oct 28, 2005 at 09:54:21PM +0200, Derk-Jan Hartman wrote:
>
>> Hello Marian,
>>
>> I applaud that you are so enthusiastic in your development efforts,
>> but I (and probably others) would also very much appreciate it if you
>> discussed making intrusive changes like this in the future. UDP is
>> not useless and has VERY specific uses for many of us. Please concur
>> with other developers on what is the best method of implementing
>> something.
>>
>> DJ
>>
>>
>> On 28-okt-2005, at 21:42, Subversion daemon wrote:
>>
>>
>>> r13006 | fkuehne | 2005-10-28 21:42:50 +0200 (Fri, 28 Oct 2005) | 1
>>> line
>>> Changed paths:
>>>   M /branches/0.8.4/modules/gui/wxwidgets/streamdata.cpp
>>>   M /branches/0.8.4/modules/gui/wxwidgets/wizard.cpp
>>>
>>> * reverted [12957]. UDP-support is a must. don't remove it from the
>>> interface by overriding it with RTP
>>>
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>>>
>>>
>>
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>>
>
>
> ---------------------------------------------------------------------- 
> ----
> ----                                                                   
> ----
> ----   Marian Durkovic                       network   
> manager         ----
> ----                                                                   
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> 301   ----
> ----   Computer Centre, Nam. Slobody 17      Fax: +421 2 524 94  
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> md at bts.sk    ----
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