[RTW] List is now open

Mon Oct 11 18:31:13 CEST 2010

There needs to be: 
1) A way of ensuring that media packets being sent to a "UDP URL" are being sent to a cooperating device, which means there must be some sort of handshake which relies on an out-of-band exchange as well. STUN Connectivity Check probes and responses meet this requirement, if it is enforced that this handshake must complete prior to sending media traffic. 
2) A way of describing how these media packets will be encapsulated, especially if audio and video will be on the same UDP port. RTP meets this requirement (if you're ok with using SSRC for multiplexing, for the latter case). 

You do raise the good question as to whether or not peer-to-peer application-level multicast overlays are in scope or not. 

Matthew Kaufman 

From: "Silvia Pfeiffer" <silviapfeiffer1 at gmail.com> 
To: "Justin Uberti" <juberti at google.com> 
Cc: "Stefan Håkansson LK" <stefan.lk.hakansson at ericsson.com>, rtc-web at alvestrand.no, "David Singer" <singer at apple.com>, "Harald Alvestrand" <harald at alvestrand.no> 
Sent: Sunday, October 10, 2010 5:44:02 PM 
Subject: Re: [RTW] List is now open 

It seems to me that works nicely for 1-to-1 RTC. It wouldn't even require introduction of RTP/RTSP but can simply be pushing encoded a/v packets over the network as fast as possible on the given URL, which would then be a UDP URL? 

I guess for multi-peer RTC a different approach on the network would be required or would it be a full mesh? 

Silvia. 

On Mon, Oct 11, 2010 at 10:43 AM, Justin Uberti < juberti at google.com > wrote: 

My idea is that we will tie these various pieces together like a filter chain, i.e. 

<device> -> [encoder] -> [transport] -> [decoder] -> <video> 

where the connections between pieces are made by passing URLs around. (i.e. opening a device yields a URL for a stream, which is supplied to the encoder; at the other end, streams coming from the decoder are identified by a URL, which can then be passed directly to a <video> tag or WebGL texture.) 

Other combinations are of course possible, such as direct access to [transport], in the case of a web real-time game, or combining <device> -> encoder -> websocket, for doing live (non-realtime) broadcasts. 

We're still figuring out the right interfaces for encoder/decoder; for transport, hopefully the draft I proposed can serve as a reasonable starting point. 

--justin 

On Sun, Oct 10, 2010 at 4:26 PM, Stefan Håkansson LK < stefan.lk.hakansson at ericsson.com > wrote: 

That's right, a lot of things remain regarding protocols and other stuff. But IMHO <device>, StreamAPIs and <audio> and <video> should be part of the puzzle! 

--Stefan 

From: Silvia Pfeiffer [mailto: silviapfeiffer1 at gmail.com ] 
Sent: den 11 oktober 2010 01:23 
To: Stefan Håkansson LK 
Cc: Harald Alvestrand; rtc-web at alvestrand.no ; David Singer 

Subject: Re: [RTW] List is now open 

Hi Stefan, 

I have seen those, thanks. That's actually the reason why I asked: because I have already seen it work with the <device> element and I wondered what the remaining challenges were. It seems there is lots of discussion about protocols and codecs. 

Cheers, 
Silvia. 

On Mon, Oct 11, 2010 at 9:49 AM, Stefan Håkansson LK < stefan.lk.hakansson at ericsson.com > wrote: 

Silvia, 

you might be interested in some experimenting we've done with media streams and <device>: https://labs.ericsson.com/developer-community/blog/beyond-html5-conversational-voice-and-video-implemented-webkit-gtk (you can track back to earlier posts). 

BR, 
Stefan 

From: rtc-web-bounces at alvestrand.no [mailto: rtc-web-bounces at alvestrand.no ] On Behalf Of Harald Alvestrand 
Sent: den 9 oktober 2010 10:12 
To: Silvia Pfeiffer 
Cc: rtc-web at alvestrand.no ; David Singer 
Subject: Re: [RTW] List is now open 

On 10/09/10 03:17, Silvia Pfeiffer wrote: 

Thanks for the general invite! 

I wonder: has the HTML5 device element been looked at ( http://dev.w3.org/html5/html-device/ ) and what are the problems with that solution? 
We're the ones who have to look - and some on the list have been closely involved with writing the <device> spec. It would be surprising to me if they are not part of the solution - but just part. 

As far as I know, it's still not clear how to tie a <device> to a media stream - given that media streams aren't defined yet, this is not very surprising :-) 

Cheers, 
Silvia. 

On Sat, Oct 9, 2010 at 5:28 PM, David Singer < singer at apple.com > wrote: 

Cool, thanks Harald 

as I said during the day, I'd like to separate (as much as possible) "why is real-time communications on the internet hard?" (which is true, but a subject the IETF, the ITU, and others are also grappling with) from "what is interesting/challenging about real-time communications *in the web*?" -- which I take to mean in pages shown by a browser. 

On Oct 8, 2010, at 4:24 , Harald Alvestrand wrote: 

> Cullen (I think) has changed the permissions on the list, so that now everyone can subscribe, and the archives are open. 
> 
> If you know of people you think should be on the list, please ask them to subscribe! 
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> Harald 
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David Singer 
Multimedia and Software Standards, Apple Inc. 

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