[RTW] [dispatch] Charter proposal: The activity hitherto known as "RTC-WEB at IETF"

[Stefan Håkansson LK]

I agree to that there are situations when a fallback to http (or perhaps WebSockets for a more efficient transport!) is required.

But I don't think the http streaming solutions are the answer. Those solutions to my understanding build on chopping up a stream into segments, and each segment is represented by a file. Each segment is typically several seconds long, and that is not sufficient for conversational services where the mouth-to-ear delay should be far below 1 second (yes, we should discuss if there should be a requirement, and what it should be in that case).

Sure you could use much shorter segments, but with all the encapsulation/wrapping data the overhead would get really big. 

> -----Original Message-----
> From: Harald Alvestrand [mailto:harald at alvestrand.no] 
> Sent: den 17 januari 2011 19:33
> To: Marshall Eubanks
> Cc: Bernard Aboba; Stefan Håkansson LK; tom.taylo at huawei.com; 
> markus.isomaki at nokia.com; rtc-web at alvestrand.no; dispatch at ietf.org
> Subject: Re: [dispatch] [RTW] Charter proposal: The activity 
> hitherto known as "RTC-WEB at IETF"
> 
> Another way (that I know is in production) is to use RTP with 
> a thin shim layer (length fields) to provide packet 
> separation, straight over TCP. If we are certain we have to 
> support RTP-over-UDP, that might be the solution that has the 
> lowest extra implementation cost over the UDP solution.
> 
> But I suspect this will have to  be decided based on a set of 
> requirements, not just a beauty contest.
> 
> What is the added value of the MPEG-2 wrappers?
> 
> On 01/17/11 18:23, Marshall Eubanks wrote:
> > On Jan 17, 2011, at 10:59 AM, Bernard Aboba wrote:
> >
> >> +1.
> >>
> >> One place where we could "spend our energy wiser" might be 
> on enabling interoperability
> >> of HTTP transported realtime media.   Although 
> peer-to-peer traffic is more desirable when
> >> possible, "HTTP fallback" is in practice required a significant 
> >> fraction of the time, due to the prevalence of highly 
> restrictive firewalls.
> > I would agree, and that raises the issue of the "wrapper" 
> for HTTP streaming. Note that Apple uses MPEG-2 TS for the 
> wrapper for its live http video streaming.
> >
> > (  Each media file MUST
> >     be formatted as an MPEG-2 Transport Stream, an MPEG-2 
> Program Stream,
> >     or an MPEG-2 audio elementary stream  - 
> > http://tools.ietf.org/html/draft-pantos-http-live-streaming-01 )
> >
> > While this is certainly standards based, I do not think it 
> matches or interoperates with anyone else's HTTP streaming. 
> And, of course, this is an I-D still. Flash also does http 
> streaming, but I believe it uses its own, proprietary, wrapper.
> >
> > So, is specifying a media transport protocol for http 
> streaming in scope ?
> >
> > Regards
> > Marshall
> >
> >
> >>> From: stefan.lk.hakansson at ericsson.com
> >>> To: tom.taylo at huawei.com; harald at alvestrand.no; 
> >>> Markus.Isomaki at nokia.com
> >>> Date: Sat, 15 Jan 2011 15:17:51 +0100
> >>> CC: rtc-web at alvestrand.no; dispatch at ietf.org
> >>> Subject: Re: [RTW] [dispatch] Charter proposal: The 
> activity hitherto known as "RTC-WEB at IETF"
> >>>> I agree that at least for the time being it is more fruitful to 
> >>>> focus the energy elsewhere. There is plenty of useful 
> work that can 
> >>>> be done about media transport (the datagram service and the 
> >>>> potential bytestream
> >>>> ) and the associated APIs, and I suggest we focus on 
> that. We can 
> >>>> try our luck with the codec thing later on.
> >>> I agree. Codec discussions seem to go on forever, and we 
> could spend 
> >>> our energy wiser.
> >>>
> >>> Stefan
> >>>
> >>> PS Sorry for answering late, but I did not follow dispatch. I 
> >>> thought all related messages would go on rtc-web as well. 
> So those 
> >>> of you who do not follow dispatch: perhaps you should 
> look into the dispatch archive.
> >>> _______________________________________________
> >>> RTC-Web mailing list
> >>> RTC-Web at alvestrand.no
> >>> http://www.alvestrand.no/mailman/listinfo/rtc-web
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> >> dispatch at ietf.org
> >> https://www.ietf.org/mailman/listinfo/dispatch
> >
> 
>