[linux-dvb] Re: DVB and MPEG-4

[Peter Maersk-Moller <peter@maersk-moller.net>]

Hi Alexandre

Alexandre CONRAD wrote:
> > Ok, so we have a multicasted stream. Probably an RTP based stream.
> > Players like mp4player and Quicktime should be able to play it if
> > we had the SDP file or means for generating it. It would be interesting
> > to see if any SDP announcements are made on the interface as well.
> > Does anyone know how to get the SDP info for these channels ? 
> I haven't tested that :
> You have 2 files there : eg : "Deejay_Tv.asx" & "Deejay_Tv.nsc".
How did you get them ? Can you share them ?

> The ASX file has all the infos about the clip. The NSC file has all the 
> streaming / broadcasting info.
So a proprietary non standard solution.

> You should be able to read these files with Windows Media Server (I 
> think). At least, the program that have generated them. But after 
> talking with Eutelsat, I pretty much know how this works. And they are 
> using Windows Media Server.
So a proprietary non standard closed insecure solution subject change
to without further notice :(

One should think Eutelsat was wiser.

Hell, it might not even be MPEG-4 but rather MS-MPEG-4 :(

> > BTW, it is a dangerously channel to tune into. It means that it will
> > typically be sending a full feed (45Mbps) of multicasting traffic
> > towards you and your PC will quite often forward this traffic to
> > your default route (or your multicast route). 
> These MPEG4 channels are only 450kb/s. But maybe I don't know enought 
> about satellite to argu on that. :)
I thought they were broadcasting in better quality. Anyway, 19x450kbps
is approx 8.5Mbps. That's usually much more than needed to saturate a
home network (10BaseT or 802.11b). What is worse is that it can work
as a fine denial of service attack on your home router since such a beast
usually can't handle high load of multicasted traffic. After all these
router (or CPEs) only have a slow embedded processor to handle it all.

So disabling IP-forwarding or using a filter on your PC receiving
multicasted traffic from satellite is advisable.

--PMM



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