[mythtv-users] Back of the envelope calcs for minimum network speed

[Fedor Pikus]

On 9/5/05, Brian McEntire <brian.mcentire at gmail.com> wrote:
> 
> Hi -
> A question about network capacity:
> 
> I'm planning to put a front end by the TV, and a back end in a different 
> part of the house. The primary purpose for this MythTV setup is HDTV 
> viewing.
> 
> Some early HDTV recordings are about 2.4 GB for 30 minutes.
> 
> This works out to 2.4 * 10^9 * 8 bits/B / 30 min / 60 sec/min= 10.7 Mbps


About 1.37 MB/sec. You can get this from 802.11g, but it's right at the 
limit of the standard 54 MBps (and only if you don't use the network in 
mixed mode, if you add 802.11b clients the throughput will drop). However, 
this is well within the limits for the "fast" 11g, i.e. proprietary 
extensions which typically double the speed of the network (you've probably 
seen 108 Mbps devices advertised, that's them). The catch is, they are 
usually 108 Mbps to each other, and 54 Mbps to another brand, if you're 
lucky. 

I have a network of several Viewsonic WAP/Bridge devices (WAPBR-100, CompUsa 
sells them on-line if you can't find them) and I get 2.4 MB/sec transfer 
rate to and from my Myth box. These are ethernet to wireless bridges, not 
wireless adapters, which is the best since you don't have to mess with 
wireless drivers - you just take all your bridges to one place, connect them 
to a PC one by one, configure them all, one as a WAP and the rest as 
bridges, and then connect them to any ethernet-enabled device, and with no 
changes to the device you're now connected to wireless.

Fedor

For streaming from the backend to the frontend (aka accessing via NFS?) it 
> appears it will exceed Ethernet speed and require fast ethernet. I don't 
> have cable run, so my question is, for a strong signal, is it reasonable to 
> expect a quality stream over 54 Mbps wireless-g or is running CAT5/6 a 
> better bet?
> 
> Thanks!
> 
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> 


-- 
Fedor G Pikus (fpikus at gmail.com)
http://www.pikus.net
http://wild-light.com
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