pfarrell;346451 Wrote: 
> DeVerm wrote:
> > How can you say that Phil? A streaming redbook WAV takes 1.35 Mbps;
> if
> > it's encoded to flac it will be less than 1 Mbps. The wifi link can
> > handle 54 Mbps 
> 
> No, the theoretical max speed of 802.11g is 54mbs (small b, bits, not
> bytes which is usually but not always B)
> 
> RedBook audio is
> = 1,411,200 bits/second
> = 176,400 bytes/second
> = 172 Kbytes/second
> 
> With flac, you may only need half that.
> 

Hey, we say the same... I never used the capital "B" so I referred to
bits. Your 1,411,200 bits/seconds are the same as my (shorter) notation
of 1.35Mbps. calc: 1Kb = 1024b and 1Mb = 1024Kb which makes 1.35Mbps =
1415577.6bps which is near enough the real thing for the discussion
;-)

But technically you are wrong because the "m" means milli while you
mean mega which is a capital "M", so it's Mbps or Mb/s. Just 9-zeros
difference there ;-) Now I see, you see my Mbps but read it as MBps !

> Realistically, you get no more than a quarter of rated speed, point to
> point, best case. One tenth is more realistic if there is any
> interference, such as microwave ovens, bluetooth, zigbee, neighbors
> using WiFi, etc.
> 
> So if you use one tenth 802.11g, you have 5.4mbs really.
> Which is only about four full speed PCM data streams.

Well, I can talk 24/96 HD down to crappy too but it doesn't work that
way. The audio is sent as a TCP stream and wifi stuff so we have
overhead which is -never- gonna reach 40% extra. 54g really does 54Mbps
if signal and quality levels allow that speed. If you can't do that
point-to-point you have a problem. I can and do it but even my nice
DLink-4500 router will fall down if I start doing encryption like wpa.
This is because it's CPU can't handle it. Maybe the SB also has a hard
time decoding it. I still don't understand why people use it on
audio-streams (use 2nd router!) unless your songs are about your
financial state of affairs ha! If the microwave interferes buy a new
one or move the router/SB a bit; select different channel than the
neighbours wifi or put directional antenna or even amplifier on the
router to end the crap for good but you -will- get 54 Mbps in the end
which will be half the speed of 100BaseTx. If you can't get there, it
can be improved to make it happen. We stream DVD over 54g!

> If you run WiFi from the SqueezeCenter to the router/hub, and from the
> router/hub to your SqueezeBox, Duet, Transporter, etc. then you are
> already using two hops. And your two hops are causing contention on
> the
> CSMA/CD channel.

First I don't believe anyone has experienced that with just 2 streams.
But also I can't calculate that. Let's say I'm a speaker on the channel
like SC. I want to speak but I'm nice and wait because I sense a carrier
from another speaker (router->SB) on the channel. This is good because
we don't get a collision that way. Now the carrier is gone and I speak
but whooo I detect a collision! I stop and wait a random time. The
other speaker does the same and we don't interfere anymore for some
time. remember that every audio-stream-speaker is only speaking 1/50th
of the time.
Also, when you are in the same subnet, it is actually only 1 hop as the
router/wifi is operating on layer 2. But I understand your meaning that
the stream is on the air twice.

> So the prudent rule of thumb is to hard wire your server with
> SqueezeCenter to your WiFi router, and use the WiFi only to deliver
> one
> to your Duet/TP/etc.
> So put your music library on an old PC, stick it in the basement, run
> Cat6 wire to your Router and listen to music.

Agree, not a bad rule at all because most wifi installations are
troubled. I do it too because the cable is there. But how many SB users
did a wifi-site-survey before&during their wifi-install? I bet <1% ! I
am that <1% probably and only did it because it used to be part of my
job plus we need multiple wifi-systems for our uplink to the Internet
(boat, no DSL) and use amps and stuff to do that reliably. Anyone with
a laptop with wifi and free utils from the web can do it and improve
their wifi big time within the hour!

But even a bad setup will do better than 5.4Mbps or the whole kit is
useless. Even my $50 Linksys does better!

ciao!
Nick.


-- 
DeVerm
------------------------------------------------------------------------
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View this thread: http://forums.slimdevices.com/showthread.php?t=53018

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