FW: [Malvern] Video Networking

[Ian Pascoe]

Chris / Rik

Thanks for your replies guys.

OK, so looking at a 10 base T network running at 10mb, to get a fully
un-compressed data stream from a DVD file would totally engulf the network
at one extreme, or looking at the average data rate still only allow one
data stream to be viewed; ie average rate of 6-7 Mb would require a minimum
bandwidth of 12Mb to view 2 data streams.  Or am I missing something
fundemental in the way networks work?

Taking it to the next level of a 100 base T network with a bandwidth of
100Mb this would give the potential of about 15 data simultaneous streams
with a bit of bandwidth left over.  In this case if everything was sourced
from one server and one HD would you then run into problems with the amount
of data that could be read off the HD to provide these data streams.  I know
that for instance you could get around this by dumping the file into memory
and streaming it from there but keeping it simple with the assumption that
what comes off of the HD goes straight out into the network.

Sorry about keeping on with this but it niggles!

Ian

-----Original Message-----
From: malvern-bounces at mailman.lug.org.uk
[mailto:malvern-bounces at mailman.lug.org.uk]On Behalf Of Chris Eilbeck
Sent: 17 March 2006 23:46
To: malvern at mailman.lug.org.uk
Subject: Re: [Malvern] Video Networking


On Fri, Mar 17, 2006 at 09:33:37PM -0000, Ian Pascoe wrote:
> Evening all
>
> Following on from the conversations at Geoff's on Wednesday - apple cake
and
> quiche very much up to standard thanks Geoff.
>
> A question for those of you involved with networks.
>
> If you have a LAN with a server and a number of PCs off of it, what is the
> limitation to how many people could view the same video source if stored
on
> the servers HD?  Would this be limited by the server's hardware, network
> bandwidth or something completely different.  The source would be fall
blown
> DVD material.

You'd have trouble doing this over most cheap networking technologies.
You'd definitely have to have a switch rather than a hub.

> I presume that within any network the Tx and Rx have a small buffer on the
> network cards that once filled is downloaded into the PC?

Yep.

> Does anyone know what the transfer rate is for data coming off of a DVD
data
> file?  ie CD Audio is something like 128k/bps.

CD audio is 1.5mbps.  DVD video can be upto 10mbps but is usually around
6-7mbps.

> Why am I asking - for no other reason than would it work at home - ie you
> load your DVD onto a HD and you can take your laptop / PC in which ever
room
> to watch your favorite film whilst someelse is doing the same in another
and
> so on.

That'd be cool.  Have a look at http://www.videolan.org/

Chris
--
Chris Eilbeck
MARS Flight Crew                              http://www.mars.org.uk/
UKRA #1108 Level 2                                                UYB
Tripoli UK Member #9527                                          LSMR

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