All things related to multicast

["Greg Shepherd" <>]

On 7/24/08, Frank Fulchiero <> wrote:

On [Jul 24], at 6:21 PM, Greg Shepherd wrote:

I don't think you should need a web browser to find a video stream.
If the goal is an easy way for most viewers  to watch a video channel, then the video player should show the available channels automatically.

Which video player?

What I envision does not exist yet in the multicast world (afaik)...except in a primitive form in VLC with SAP discovery.
Or in somewhat closed systems, like VBrick's. Not criticizing this approach, btw, sometimes you HAVE to control streams and clients, and VBrick is a good solution here.

Personally, I am more interested in promoting open programming over multicast, especially in educational and research environments.
I guess the closest that would come to what I envision is an open-source version of iTunes...combining discovery of media with the ability to play it.
With a good system for organizing many files and sources. Independent of web browsers, but can also interface to them.

A new multicast announcement/discovery open standard should also be independent of players, then their developers and manufacturers could decide whether to interface to it or not. That also brings up the question whether multicast streams should be treated any differently than unicast ones in discovery/announce systems.

This follows the broadcast television model: turn on the TV, see what's on, and then decide what to watch. You don't go to NTSC-Google to find a channel, though that might be fine if it were built into the television as a dedicated app. and integrated with the television seamlessly.


This works for TV because there is a national TV standard. With streaming digital media, there are many standards to choose from. ;-)

Looking at the entire landscape, yes. But there do not appear to be that many standards in multicast streaming: UDP vs RTP for delivery. MPEG2 vs MPEG4 for encoding/decoding (granted, several parts, levels and profiles). SAP for announce/discovery.

Oh really? Which variation fo MPEG4? Who's? Now toss in DRM.

Yes, I realize your focus is for R&E, but the companies behind the commercial players can't even spell R&E.
 

Yes, VLC does a great job on most content, but how much commercial content uses it?

That is a good point. Richard Mavrogeanes probably scared them all off! ;-)
Sorry Richard, could not help myself...

YouTube uses a browser quite successfully I gather. But it's no less a proprietary solution than opening WMP to look for content.. or QT, or VLC, or Real.. But if a content directory service was available via a web browser, then the SDP file would open the correct player and all is well.

Yes, that is true. For some reason it seems more elegant to also have the programs show up in a player, like in iTunes.
Or, say the iPhone YouTube app. But open-source open-standard ones, that are not controlled by any one manufacturer.

A few other odd thoughts...

1. I think it's possible to hierarchically structure a long list of programs to make it more manageable. Good example here again is  iTunes.

But iTunes manages "my" files, which are constrained. If we're going to have countless content sources updated schedules I want a searchable calendar. And I'd prefer it not to require yet another application download as a roadblock to adoption. Stick it on the web and anyone can get to it from any device. 

2. There are interesting features in the SDP standard that could possibly be used in a new announce/discovery system. The a=cat:<category>  attribute "gives the dot-separated hierarchical category of the session." Not sure any clients use this...And then there is the fact that you can make up any attribute to extend SDP. For example, VLC uses "a=x-plgroup:Name" to group streams in one Program Group. Lots more could be done with the "a" categories. Well, just thinking out loud...

These fields could also be searchable. 

Finally, I am not pushing SAPs, just trying to best use them while waiting for something better to come along. Thanks for all your comments.

We've been waiting for something better for well over 10 yrs. But then we've also been waiting for the critical-mass adoption of mcast sweep over the Internet....

In the mean time, mcast deployments for IPTV services in edge networks have been rapidly expanding globally. They don't use SAP. The content schedule is provided by some proprietary middle-ware, but then the target devices are proprietary as well.

Greg

Frank Fulchiero
Digital Media Specialist
Connecticut College