[mythtv-users] Yet another potential FrontEnd

Richard Stanaford rstanaford at gmail.com
Sat Aug 16 04:29:31 UTC 2008


David Schlenk wrote:
>
>
> On Fri, Aug 15, 2008 at 12:05 AM, Jean-Yves Avenard
> <jyavenard at gmail.com <mailto:jyavenard at gmail.com>> wrote:
>
>     802.11g only the mini ; I wish it was 802,11n
>     Can't stream HDTV (1080i) with 802.11g unfortunately ; had to wire
>     the menu
>
> Not to take this off topic but...
> I see this piece of info on the list all the time and often wonder if
> I'm breaking the laws of physics or if people actually just have
> really bad coverage in their homes. I stream mpeg2 HD with 802.11g all
> the time. Typically bitrates from broadcast TV top out around
> 19Mbps... doesn't g potentially go up to 54Mbps? Even if you halve
> that you're still rocking 27Mbp.. plenty of bandwidth. Of course I'd
> rather use wired if I have the chance but g isn't unusable for this
> task if you spend a few minutes designing your wireless network
> effectively.
>
> To be a little more on topic. This is a ludicrously expensive piece of
> kit. It probably can't do mpeg4 1080p playback anyway, so put together
> some 3 year old crap and slap in a 5200 or 6200 in a crappy case, put
> it in a closet and run some cable to your TV for audio, video and
> remote sensor. I'd much rather have the box completely out of sight
> than spend a couple hundred dollars trying to make it quiet and nice
> looking. I just put together an Athlon 1800+ based frontend using
> parts I found in my basement (I do some moonlighting tech support for
> people so end up with broken crap all the time... I scavenge the
> useful things and recycle the rest). It plays back HD content using
> XvMC no problem, I put it in the closet so we can't hear it, and it
> cost me nothing (well, I probably bought a couple of the components at
> one point, but still).
> ------------------------------------------------------------------------
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users at mythtv.org
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>   
Wireless is contention based, shared media, like Ethernet when
everything was half duplex, so the best your going to be able to do is
50-60% of the available bandwidth under the best of circumstances.  But
it should be plenty.  Data storage is termed in bytes of data (B), while
data transfer is referred to in bits of data (b)... so...

HD records at... what...  8 GB/h (Gigabytes per hour).   Eight bits per
byte yields (8,000,000,000 B/h * 8 b/B) =  64,000,000,000 b/h. (bits per
hour). 

64,000,000,000 b/h / 3600 seconds = 17,777,777 bits per second.   Easily
sustainable, when you have 50 to 60 percent of 54 Mbps available to you
(50% of 54,000,000 is 27,000,000).  Again, in the best of cases.

In the United States, the FCC has allocated 13 channels within the
2.4GHz spectrum for wireless, but channels 1, 6, and 11 are the ones
most suitable for use.  So it is going to be a combination of sharing
the limited resource of three clear channels along with any 2.4GHz
cordless phone within 1000 feet that channel-walks on you.  The phone
will win every time, which might explain intermittent success if anyone
has encountered it and wondered why.

It's a bit like astronomy.  It's doable, if the sky is clear enough.  *grin*
-Rich


More information about the mythtv-users mailing list