[streaming] Re: (no subject)

[Dave Schroeder]

We are currently distributing 12 TV channels using MPEG-4 (Part 2) on a 
100mbit multicast network, but we are using QuickTime to do the 
encoding and delivery (though we support VLC for playback). We are in 
the process of expanding to 77 channels that will also delivered via 
multicast, and will be moving to H.264. We also distribute optional 
closed captioning for each channel. We used QuickTime because we wanted 
to distribute the video in open formats (e.g., MPEG-4, AAC) and open 
protocols, but also wanted a product supported by a commercial vendor.

It is doubtful that there is any equipment you would be able to use 
that would not require you to buy some kind of a tuner for each 
channel. Also, if you're planning on doing a high quality broadcast, 
you shouldn't plan on being able to do more than two channels per 
server if you are encoding in software. If you are doing hardware 
encoding, you can do more, but I'm not familiar with any equipment that 
would allow you to do multiple channels (other than simply getting 
multiple TV tuner cards and multiple servers to hold them).

In order for this to work for you, ALL of your clients will need to 
have multicast connectivity between themselves and the video server(s). 
But, from a network standpoint, yes, it is definitely possible...but 
only you know the datarate you plan to encode at. If you are doing 25 
channels at, say, 1 Mbps each, and they will all be used all the time, 
that's 25 Mbps of used bandwidth plus some overhead. A properly 
configured switched 100mbit network will handle it, but you need to 
keep in mind your limitations. For example, we don't have all channels 
in use at all times, but in our case, all of our 100mbit clients across 
campus, which number over ten thousand, are connected via 1Gbit, and in 
turn a 10Gbit backbone, so even 77 channel delivery across the whole 
campus is not a concern.

For more information about our installation, see:

http://datn.wisc.edu/about/

Regards,

Dave Schroeder                 |    University of Wisconsin - Madison
Email: das at doit.wisc.edu       |   Division of Information Technology
Pager: das-pager at doit.wisc.edu | B263 Computer Science and Statistics
Pager: +1 800 449-4951         |              1210 West Dayton Street
Phone: +1 608 265-4737         |        Madison, Wisconsin 53706-1685

On Feb 27, 2005, at 11:22 AM, Ugo Angelini wrote:

> good morning,
>  I am trying to build one net of 150 client.On this net I would want 
> to make distribution of tv via net and it would appeal to me to use 
> VLS - VLC.
>  My net is a fast ethernet Cisco based. I have some problems: i must 
> distribute 25 TV channels simultaneously (in multicast)and i have some 
> doubt that my net can make it; what do you think about it?
>
>  In the same net every client would have to be able to go in Internet, 
> can it possible?
>
>  I must transmit 25 contemporary channels tv, do you know a hardware 
> from being able to use under linux that it can avoid to me to buy 25 
> cards TV MPEG?
>  I would want to use a server of streaming dual processor xeon 1 GHz, 
> what do you think about it?
>  I'm afraid to disturb with all these questions, but I am not 
> successful to find sufficient documentation on web, not even houses 
> study.
>       Thanks for all,
>                            Ugo Angelini.

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