Sending Pd-audio over Wifi would have the advantage that no extra gear is needed at the transmitter side, simplifiying the setup of a wearable live performance computer. Therefore this would be the method of my preference, if it is possible at all. <br>
<br>This weekend I did some experiments with [udpsend~] and [udpreceive~] over Wifi. I soon found that using a wireless router makes little sense. Wifi is 'half duplex', meaning it can't send and receive at the same time, so the router is either receiving from one computer or sending to the other. A waste of time.<br>
<br>I learned about 'ad hoc networks', where computers can be paired via Wifi and talk to each other directly, without a router. Never knew about this before. What a cool option that is. Found a howto here:<br><br>
<a href="https://help.ubuntu.com/community/WifiDocs/Adhoc">https://help.ubuntu.com/community/WifiDocs/Adhoc</a><br><br>In ad hoc mode, latency is lower, although on average not as low as over cable, and with more fluctuation. Moreover, there was considerable packet loss, which did not happen in wired LAN. Therefore, tcp protocol should probably be used instead, to check for packet loss and eventually resend packets.<br>
<br>I found that [udpsend~] can not send packets of 64 samples. It seems that 256 samples is the minimum. Why? Maybe it is best to pack each signal vector in a list and use the [tcpsend] / [tcpreceive] combo instead.<br><br>
A well-known issue with music streaming is clock drift, caused by the slightly different clock speeds between audio cards. This also happens when sending over a local network (wired or wireless). Clock drift is typically 0.0001 to 0.001 ratio of nominal sample rate. A small difference, but it causes one buffer to be skipped or duplicated once in a while. To compensate, the signal should be resampled to match the receiver's sample rate. This would not require a complicated interpolation scheme, but still it would probably need one or more new Pd classes. An interesting article about clock drift and possible solutions is here:<br>
<br><a href="http://www.carot.de/Docs/AES_Tokyo.pdf">http://www.carot.de/Docs/AES_Tokyo.pdf</a><br><br>If further experiments are promising enough, I would try this board for the receiver:<br><br><a href="https://www.olimex.com/Products/OLinuXino/A13/A13-OLinuXino-WIFI/">https://www.olimex.com/Products/OLinuXino/A13/A13-OLinuXino-WIFI/</a><br>
<br>Otherwise, I would just be happy to have learned about ad hoc networks. This can come in handy for other purposes too, for example when synching Pd computers.<br><br>Katja<br><br><br><br><br><div class="gmail_quote">On Fri, Mar 1, 2013 at 9:34 PM, Phil Stone <span dir="ltr"><<a href="mailto:pkstone@ucdavis.edu" target="_blank">pkstone@ucdavis.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left:1px solid rgb(204,204,204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div>These Line 6 units are well respected
in the electric bass world, especially considering their moderate
price. I think bass players appreciate tight timing, and the low
lag may be one reason these units are popular. Also, they have
proven to be rugged enough to be "road-worthy". They can also
model the hi-frequency lossiness of cords, though that seems of
dubious value in your case.<span class="HOEnZb"><font color="#888888"><br>
<br>
<br>
Phil</font></span><div><div class="h5"><br>
<br>
<br>
On 3/1/13 12:24 PM, katja wrote:<br>
</div></div></div><div><div class="h5">
<blockquote type="cite">Apparently, Line 6 managed to build a digital 2.4 GHz
wireless with <4 ms latency, the Relay G30, G50 etc . They do
not write it in the specs, but most users don't notice latency and
when they do, their support is speaking of latency as low as that:<br>
<br>
<a href="http://line6.com/support/thread/33898" target="_blank">http://line6.com/support/thread/33898</a><br>
<br>
This weekend I will do some WiFi experiments and see how fast it
can go locally, using mrpeach udp and tcp classes. If it works,
one could use a wireless router which has no other task than
routing Pd audio, and the computer at the receiving end could be a
cheap headless board with no other task than receiving Pd audio
and converting it to analog. Together the receiving device could
be the size of a weight-watcher's lunch box, while at the
transmitter side the computer's built-in stuff is used. Maybe I'm
a bit naive here, anyway I'll report results from experiments.<br>
<br>
Katja<br>
<br>
<br>
<div class="gmail_quote">On Fri, Mar 1, 2013 at 2:14 PM, richard
duckworth <span dir="ltr"><<a href="mailto:richduckworth@yahoo.com" target="_blank">richduckworth@yahoo.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="border-left:1px solid rgb(204,204,204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex">
<div>
<div style="font-size:12pt;font-family:arial,helvetica,sans-serif">
<div><span>OMG - that's really high! Maybe Tranz have a
belt holder solution - they do look kind of bulky
though! Maybe worth dropping them a line, see if
they'll help the Pd community </span></div>
<div>
<div style="font-style:normal;font-size:16px;background-color:transparent;font-family:arial,helvetica,sans-serif"><span><br>
</span></div>
<div> </div>
<div>Rich Duckworth<br>
Lecturer in Music Technology<br>
Department of Music<br>
House 5 <br>
Trinity College <br>
Dublin 2<br>
Ireland<br>
Tel 353 1 896 1500<br>
<br>
</div>
</div>
<div>
<div>"Digital? <br>
Is that the thing where they take a good old sine wave
and they chop it up into little bits?" --- Rupert Neve<br>
</div>
<div style="font-family:arial,helvetica,sans-serif;font-size:12pt">
<div> </div>
<div>
<div>
<div dir="ltr"> <font face="Arial">
<hr size="1"> <b><span style="font-weight:bold">From:</span></b>
katja <<a href="mailto:katjavetter@gmail.com" target="_blank">katjavetter@gmail.com</a>><br>
<b><span style="font-weight:bold">To:</span></b>
Antoine Villeret <<a href="mailto:antoine.villeret@gmail.com" target="_blank">antoine.villeret@gmail.com</a>>
<br>
<b><span style="font-weight:bold">Cc:</span></b>
richard duckworth <<a href="mailto:richduckworth@yahoo.com" target="_blank">richduckworth@yahoo.com</a>>;
"<a href="mailto:pd-list@iem.at" target="_blank">pd-list@iem.at</a>"
<<a href="mailto:pd-list@iem.at" target="_blank">pd-list@iem.at</a>>
<br>
<b><span style="font-weight:bold">Sent:</span></b>
Friday, 1 March 2013, 13:12<br>
<b><span style="font-weight:bold">Subject:</span></b>
Re: [PD] wireless audio from Pd to PA system
(katja)<br>
</font> </div>
</div>
<div>
<div> <br>
<div>Found more info about TI's PurePath
wireless. Latency of wireless transmission is
768 samples minimum. Added to this must be the
latencies of ad/da conversion. <br>
<br>
<a rel="nofollow" href="http://e2e.ti.com/support/low_power_rf/f/382/t/110331.aspx" target="_blank">http://e2e.ti.com/support/low_power_rf/f/382/t/110331.aspx</a><br>
<br>
Forget about it, this concept is only useful
for home entertainment.<br>
<br>
Katja<br>
<br>
<br>
<div>On Fri, Mar 1, 2013 at 1:19 PM, katja <span dir="ltr"><<a rel="nofollow" href="mailto:katjavetter@gmail.com" target="_blank">katjavetter@gmail.com</a>></span>
wrote:<br>
<blockquote style="border-left:1px solid rgb(204,204,204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex">Thanks everyone
for your answers. <br>
<br>
The case is unconventional because a
stereo line signal must be sent from the
computer. Professional wireless systems
assume mic or instrument. Consumer systems
do transmit stereo signal, but without
bothering too much about latency.<br>
<br>
Frankly, I did not expect the difficulty
to find a good solution. Initially I
wanted the wearable computer for a music
video which is to be recorded live with
sounds from natural objects. I bought the
FM transmitter so my cameraman will be
able to hear the music while he's filming.
For this purpose it is ideal. Then I
thought it would be good to use the
computer in it's wearable mode for public
performance. I figured that one of the
many wireless solutions would suit the
purpose, but didn't reckon with the
unusual requirements.<br>
<br>
Further searching brought me to a new
technology 'PurePath' from Texas
Instruments. It has a range comparable
with WiFi (30m), while it seems to work
with paired devices as in Bluetooth. I
haven't seen consumer products with this
technology, but development kits are
available. A rather convincing demo is
here:<br>
<br>
<a rel="nofollow" href="http://www.youtube.com/watch?v=0YsnZQUfVGs" target="_blank">http://www.youtube.com/watch?v=0YsnZQUfVGs</a><br>
<br>
If this system can work with low latency
it could be perfect for wireless Pd.<span><font color="#888888"><br>
<br>
Katja</font></span>
<div>
<div><br>
<br>
<br>
<br>
<div>
On Fri, Mar 1, 2013 at 11:41 AM,
Antoine Villeret <span dir="ltr"><<a rel="nofollow" href="mailto:antoine.villeret@gmail.com" target="_blank">antoine.villeret@gmail.com</a>></span>
wrote:<br>
<blockquote style="border-left:1px solid rgb(204,204,204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex">
<div dir="ltr">hello,
<div><br>
</div>
<div>those are good for what
they have been designed for
and it depends on what you
mean by "exellent sound
quality"</div>
<div><br>
</div>
<div>I've made few tests on
those few years ago and the
bandwidth could be good enough
to transmit guitar/bass signal
but nothing else for me</div>
<div><br>
</div>
<div>+</div>
<div>a</div>
<div><br>
</div>
</div>
<div><br clear="all">
<div>--<br>
do it yourself
<br>
<a rel="nofollow" href="http://antoine.villeret.free.fr/" target="_blank">http://antoine.villeret.free.fr</a><br>
</div>
<br>
<br>
<div>2013/2/28 richard duckworth
<span dir="ltr"><<a rel="nofollow" href="mailto:richduckworth@yahoo.com" target="_blank">richduckworth@yahoo.com</a>></span><br>
<blockquote style="border-left:1px solid rgb(204,204,204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex">
<div>
<div>
<div>
<div style="font-size:8pt;font-family:arial,helvetica,sans-serif">
<div><span><font size="1">Hi
Katja</font></span></div>
<div style="font-style:normal;font-size:10px;background-color:transparent;font-family:arial,helvetica,sans-serif"><span><font size="1">one
of these would
do it - check
with Thomann
tech support
for gain
issues (these
are Instrument
Level input)
They should be
fine however
as active
guitar pickups
(like heavy
style EMG
pickups)
output quite
high levels.
These type of
wireless
systems tend
to be very
rugged, have
excellent
sound quality
and long
battery life -
and you'll
want these
things. </font></span></div>
<div style="font-style:normal;font-size:10px;background-color:transparent;font-family:arial,helvetica,sans-serif"><span><font size="1"><br>
</font></span></div>
<div style="font-style:normal;font-size:10px;background-color:transparent;font-family:arial,helvetica,sans-serif"><span><font size="1"><a rel="nofollow" href="http://www.thomann.de/ie/cat.html?gf=wireless_for_guitar_bass&oa=pra" target="_blank">http://www.thomann.de/ie/cat.html?gf=wireless_for_guitar_bass&oa=pra</a></font></span></div>
<div style="font-style:normal;font-size:10px;background-color:transparent;font-family:arial,helvetica,sans-serif"><span><font size="1"><br>
</font></span></div>
<div style="font-style:normal;font-size:10px;background-color:transparent;font-family:arial,helvetica,sans-serif"><span><font size="1"><br>
</font></span></div>
<div style="font-family:arial,helvetica,sans-serif;font-size:8pt">
</div>
<div style="font-family:arial,helvetica,sans-serif;font-size:8pt"> </div>
<div style="font-family:arial,helvetica,sans-serif;font-size:8pt">Rich
Duckworth<br>
Lecturer in Music
Technology<br>
Department of
Music<br>
House 5 <br>
Trinity College <br>
Dublin 2<br>
Ireland<br>
Tel 353 1 896 1500<br>
<br>
</div>
<div style="font-family:arial,helvetica,sans-serif;font-size:8pt">"Digital? <br>
Is that the thing
where they take a
good old sine wave
and they chop it
up into little
bits?" --- Rupert
Neve<br>
<div style="font-family:arial,helvetica,sans-serif;font-size:8pt">
<div style="font-size:12pt">
<div dir="ltr">
<font face="Arial">
<hr size="1">
</font></div>
<br>
<br>
<br>
Message: 3<br>
Date: Thu, 28
Feb 2013
11:53:43 +0100<br>
From: katja
<<a rel="nofollow" href="mailto:katjavetter@gmail.com" target="_blank">katjavetter@gmail.com</a>><br>
Subject: [PD]
wireless audio
from Pd to PA
system<br>
To: pd-list
<<a rel="nofollow" href="mailto:pd-list@iem.at" target="_blank">pd-list@iem.at</a>><br>
Message-ID:<br>
<CAFY0eapPSKfw+gVaxuTr7exHqLiG+<a rel="nofollow" href="mailto:pTdu8Rk6SNTraLiys2Msg@mail.gmail.com" target="_blank">pTdu8Rk6SNTraLiys2Msg@mail.gmail.com</a>><br>
Content-Type:
text/plain;
charset=ISO-8859-1<br>
<br>
For a wearable
live
performance
computer, I am
looking into
the<br>
options of
sending
wireless audio
from Pd to a
PA sound
system and<br>
other
listeners.<br>
<br>
In a first
experiment
I've tried a
Linex FM
transmitter.
Audio quality<br>
is good
enough, and FM
transmitters
do not
introduce
latency. This<br>
option is
cheap and
flexible, as
the signal can
be received by
simple<br>
radio's, which
are even built
into cell
phones and
media players.
I<br>
would need to
boost the
transmission a
bit to make it
more reliable.<br>
This will of
course make
the equipment
illegal. Even
then, the risk<br>
that someone
else is
transmitting a
stronger
signal on the
channel can<br>
not be
excluded.<br>
<br>
Another option
could be to
send audio
over Wifi.
This would
require<br>
WLAN to be
available, and
one extra
computer (with
audio
interface) as<br>
a receiver. To
avoid extra
latency the
audio should
be sent<br>
uncompressed,
like
[udpsend~] /
[udpreceive~]
can do it.
This has the<br>
risk of packet
loss and
serious
dropouts.<br>
<br>
I've been
searching for
2.4 GHz
wireless music
receivers and
found<br>
things like
this:<br>
<a rel="nofollow" href="http://www.sitecom.com/en/wireless-music-streamer/wl-061/p/203" target="_blank">http://www.sitecom.com/en/wireless-music-streamer/wl-061/p/203</a>.
They<br>
seem to act
like external
soundcards for
your computer.
In Linux<br>
though I've
never managed
to properly
connect
multiple
soundcards
with<br>
Pd (in OSX
it's easy
using the
Aggregate
Device Editor
from Audio
MIDI<br>
Setup). Also I
guess these
devices
introduce huge
latency. With
audio<br>
over bluetooth
headsets I've
experienced
latencies up
to a second.<br>
<br>
Does anyone
use a
satisfactory
method in
practice, to
send audio
from<br>
Pd without
wires?<br>
<br>
Thanks,<br>
Katja<br>
<br>
<br>
<br>
------------------------------<br>
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