<html>
<head>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
Yeah, of course. Block size 1 and high sampling rate will make the
timing between control and audio super tight (ChucK does this, for
example). It will also eat the hell out of your CPU. It's a trade
off. This is because you start calling all the DSP functions once
every 1/192k seconds instead of once every 1.45ms. <br>
<br>
<div class="moz-cite-prefix">On 3/12/2015 1:06 PM, Alexandre Torres
Porres wrote:<br>
</div>
<blockquote
cite="mid:CAEAsFmh8cQNnOqZQX+6+X=kCfrTJ_vs8fkob+ppUM3WtEaSg3w@mail.gmail.com"
type="cite">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<div dir="ltr">Well, anyway, I was hoping for a simpler answer,
and my original guess was that the control rate limit might be
at the block size, now I'm all confused :)
<div><br>
</div>
<div>I'm seeing that maybe we can't really measure the speed
efficiently in a patch, and that Pd might actually be able to
manage tiny and fasty clocks, but that there is also a limit
on the way they are computed that depends on the block size,
right?</div>
<div><br>
</div>
<div>What about a block size of one, and a large sample rate? I
wonder if we could get control messages to work at 192Khz for
example, huh?</div>
<div><br>
</div>
<div>One way or another, I guess there might be a pretty
straightforward answer to this. I didn't find any in Miller's
book yet.</div>
<div><br>
</div>
<div>cheers</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">2015-03-12 16:42 GMT-03:00 David Medine
<span dir="ltr"><<a moz-do-not-send="true"
href="mailto:dmedine@ucsd.edu" target="_blank">dmedine@ucsd.edu</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000"> <br>
My understanding of this patch and the guts of Pd tells me
that this patch isn't really going to measure how long it
takes between each control message. What it can do is show
the time resolution of calls to sys_getrealtime, which is
Pd's method of querying the CPU clock:<br>
<br>
<font face="Courier New">double sys_getrealtime(void) <br>
{<br>
#ifndef _WIN32<br>
static struct timeval then;<br>
struct timeval now;<br>
gettimeofday(&now, 0);<br>
if (then.tv_sec == 0 && then.tv_usec == 0)
then = now;<br>
return ((now.tv_sec - then.tv_sec) +<br>
(1./1000000.) * (now.tv_usec - then.tv_usec));<br>
#else<br>
LARGE_INTEGER now;<br>
QueryPerformanceCounter(&now);<br>
if (nt_freq == 0) sys_initntclock();<br>
return (((double)(now.QuadPart -
nt_inittime.QuadPart)) / nt_freq);<br>
#endif<br>
}</font><br>
<br>
The code is from s_inter.c. It is apparent (at least in
the non-Windows part of the code) that there is a
microsecond resolution, hence 1e-6, but I could
misunderstanding this. I was able to put 1e-7 on a Windows
machine and it still worked -- I haven't had a chance to
do try it in Unix/BSD land and I don't actually want to
know what Windows is doing with this QuadPart of a
LARGE_INTEGER. Still, (on Linux and Mac, anyway) 1us is
the smallest unit of time that Pd's clocks keep track of,
so that should be the limit of what [delay] can do. <br>
<br>
The actual time it takes for Pd to deal with messages
depends on a great many things. Symbols in Pd are stored
in a hash table, so I would guess that the size of the
table (which needs to be searched) is the main factor
controlling the rate at which those messages can be
handled. However, I suspect that the number of symbols
needed to slow Pd down on a modern computer is
impractically large. Then there are control messages that
don't have hashed symbols associated with them (like
floats and bangs). Also, some external controls --
especially mouse/keyboard events and MIDI -- can be badly
timed. These tend to queue up and get spit out at the OS's
whim. Pd then simply does what it can with what it gets.
So measuring the exact time it takes to <i>do</i> control
in Pd is pretty hairy. I don't believe that meaningful
measurements of this can be done with a Pd patch. <br>
<br>
The other thing is that control messages get rolled up
between dsp ticks and are then applied immediately on the
start of the next tick. This means that two messages that
are, say, .05ms apart somewhere in the midst of a 1.45ms
block, get applied simultaneously at the start of the next
block. This also means that at 44.1kHz with a block size
of 64 samples, both of them may be anywhere from <span>
0.02</span> ms to 1.45ms late -- depending on where they
fall in relation to block boundaries. This also, also
means that if one control message happens near the end of
one block and the other happens near the start of the next
block, their distance of .05ms in physical time will be
expanded to 1.45ms. This is a very big, teeny-tiny problem
in real-time audio programming because under certain
conditions there can be serious (audible) repercussions.
This is why there is [vline~], by the way.<br>
<br>
If anyone else is interested in this stuff, I recommend
these lectures (Miller's is the first in the series):<br>
<a moz-do-not-send="true"
href="http://repmus.ircam.fr/mutant/rtmseminars"
target="_blank">http://repmus.ircam.fr/mutant/rtmseminars</a><br>
<br>
-David
<div>
<div class="h5"><br>
<br>
<div>On 3/12/2015 10:25 AM, Alexandre Torres Porres
wrote:<br>
</div>
</div>
</div>
<blockquote type="cite">
<div>
<div class="h5">
<div dir="ltr">
<div>> timer and realtime compute 2 different
things </div>
<div>> (logical time and real time). i don"t
know what </div>
<div>> your want.</div>
<div><br>
</div>
<div>I know they are different, and I don't really
know what I want either :)</div>
<div><br>
</div>
<div>I just wanted to measure how long it takes
between each control message.</div>
<div><br>
</div>
<div>you were using [realtime], and then Roman
came in and said that'd be kinda random and how
[timer] was best for it. So I tried with [timer]
and got a very nice result indeed. But I'm not
sure now if that actually relates to whats going
on... or how it is actually working.</div>
<div class="gmail_extra"><br>
</div>
<div class="gmail_extra">> what i don't
understand is your intention with </div>
<div class="gmail_extra">> the spigot in the
patch.</div>
<div class="gmail_extra"><br>
</div>
<div class="gmail_extra">just wanted to have a way
to close the message stream, but you can forget
about it</div>
<div class="gmail_extra"><br>
</div>
<div class="gmail_extra">cheers</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">2015-03-12 14:14
GMT-03:00 Cyrille Henry <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:ch@chnry.net" target="_blank">ch@chnry.net</a>></span>:<br>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><br>
<br>
Le 12/03/2015 18:04, Alexandre Torres Porres
a écrit :<br>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
"/i don't understand your patch.<span><br>
<br>
using [timer], a delay 0 will give a 0
delay...<br>
</span> logical time will always be
consistent./"<span><br>
<br>
well, I thought you were disucussing
here and reaching the conclusion that
[timer] is the one to be used to
calculate this...<br>
</span></blockquote>
timer and realtime compute 2 different
things (logical time and real time). i don"t
know what your want.<br>
<br>
what i don't understand is your intention
with the spigot in the patch.<br>
<br>
cheers<br>
c<br>
<br>
<blockquote class="gmail_quote"
style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><span>
<br>
So you mean this result is actually
inconsistent? And the implication is
that it is not going at that super fast
rate at all? Please help me understand
better about how to measure this.<br>
<br>
thanks<br>
<br>
<br>
</span> 2015-03-12 11:55 GMT-03:00 Cyrille
Henry <<a moz-do-not-send="true"
href="mailto:ch@chnry.net"
target="_blank">ch@chnry.net</a>
<mailto:<a moz-do-not-send="true"
href="mailto:ch@chnry.net"
target="_blank">ch@chnry.net</a>>>:<span><br>
<br>
hello,<br>
<br>
i don't understand your patch.<br>
<br>
using [timer], a delay 0 will give a
0 delay...<br>
logical time will always be
consistent.<br>
<br>
<br>
cheers<br>
c<br>
<br>
<br>
Le 12/03/2015 15:41, Alexandre
Torres Porres a écrit :<br>
<br>
ok, so the metro at 1ms is
because I'm using extended.<br>
<br>
as for the minimum time pd can
process and send data, what's the final
word on it?<br>
<br>
something like 1.4013e-45 ms?<br>
<br>
cause that's a lot more than an
audio rate at 44.1khz :)<br>
<br>
I thought there was a limit
control rate that was below the audio
rate, but curiously it can go over.<br>
<br>
1 sample at 44.1khz gives us
0.0226757 ms, and I was able to send
bangs at 1e-06 ms, according to [timer]<br>
<br>
check my patch attached, based
on the one that was sent here on the
thread.<br>
<br>
thanks<br>
<br>
</span> 2015-03-12 10:04 GMT-03:00
Cyrille Henry <<a
moz-do-not-send="true"
href="mailto:ch@chnry.net"
target="_blank">ch@chnry.net</a>
<mailto:<a moz-do-not-send="true"
href="mailto:ch@chnry.net"
target="_blank">ch@chnry.net</a>>
<mailto:<a moz-do-not-send="true"
href="mailto:ch@chnry.net"
target="_blank">ch@chnry.net</a>
<mailto:<a moz-do-not-send="true"
href="mailto:ch@chnry.net"
target="_blank">ch@chnry.net</a>>>>:<span><br>
<br>
hello,<br>
<br>
Le 12/03/2015 10:12, Roman
Haefeli a écrit :<br>
<br>
On Thu, 2015-03-12 at
09:17 +0100, Cyrille Henry wrote:<br>
<br>
hello<br>
<br>
this patch show the
same behaviors for a delay based metro
and a [metro].<br>
(both can do faster
than 1ms period)<br>
<br>
<br>
You're right. More
recent versions of Pd (>= 0.45?) have
an updated<br>
[metro] that supports
many more ways to specify time and the
restriction<br>
was lowered. However,
the [metro] in any available version of<br>
Pd-extended is still
limited to 1ms.<br>
<br>
sorry, i was not aware of
this old limitation.<br>
<br>
<br>
I don't understand why
you use [realtime] and not [timer] to
illustrate<br>
your point. [timer]
gives you consistent values (logical
time) while<br>
[realtime] is very
jittery and shows just some random value
depending on<br>
the current cpu usage
and probably other factors. When you
render a<br>
soundfile, the logical
time is actually the one that matters.<br>
<br>
yes, for things that stay
in pd, logical time is better.<br>
but if you want to send
midi note, [realtime] is more related to
what happens.<br>
it's just the way i
understand the original question.<br>
<br>
cheers<br>
c<br>
<br>
<br>
<br>
Roman<br>
<br>
<br>
<br>
</span>
___________________________________________________<br>
<a moz-do-not-send="true"
href="mailto:Pd-list@lists.iem.at"
target="_blank">Pd-list@lists.iem.at</a>
<mailto:<a moz-do-not-send="true"
href="mailto:Pd-list@lists.iem.at"
target="_blank">Pd-list@lists.iem.at</a>>
<mailto:<a moz-do-not-send="true"
href="mailto:Pd-list@lists.iem.at"
target="_blank">Pd-list@lists.iem.at</a>
<mailto:<a moz-do-not-send="true"
href="mailto:Pd-list@lists.iem.at"
target="_blank">Pd-list@lists.iem.at</a>>>
mailing list<br>
UNSUBSCRIBE and
account-management -> <a
moz-do-not-send="true"
href="http://lists.puredata.info/____listinfo/pd-list"
target="_blank">http://lists.puredata.info/____listinfo/pd-list</a>
<<a moz-do-not-send="true"
href="http://lists.puredata.info/__listinfo/pd-list"
target="_blank">http://lists.puredata.info/__listinfo/pd-list</a>>
<<a moz-do-not-send="true"
href="http://lists.puredata.info/__listinfo/pd-list"
target="_blank">http://lists.puredata.info/__listinfo/pd-list</a>
<<a moz-do-not-send="true"
href="http://lists.puredata.info/listinfo/pd-list"
target="_blank">http://lists.puredata.info/listinfo/pd-list</a>>><br>
<br>
<br>
___________________________________________________<br>
<a moz-do-not-send="true"
href="mailto:Pd-list@lists.iem.at"
target="_blank">Pd-list@lists.iem.at</a>
<mailto:<a moz-do-not-send="true"
href="mailto:Pd-list@lists.iem.at"
target="_blank">Pd-list@lists.iem.at</a>>
<mailto:<a moz-do-not-send="true"
href="mailto:Pd-list@lists.iem.at"
target="_blank">Pd-list@lists.iem.at</a>
<mailto:<a moz-do-not-send="true"
href="mailto:Pd-list@lists.iem.at"
target="_blank">Pd-list@lists.iem.at</a>>>
mailing list<br>
UNSUBSCRIBE and
account-management -> <a
moz-do-not-send="true"
href="http://lists.puredata.info/____listinfo/pd-list"
target="_blank">http://lists.puredata.info/____listinfo/pd-list</a>
<<a moz-do-not-send="true"
href="http://lists.puredata.info/__listinfo/pd-list"
target="_blank">http://lists.puredata.info/__listinfo/pd-list</a>>
<<a moz-do-not-send="true"
href="http://lists.puredata.info/__listinfo/pd-list"
target="_blank">http://lists.puredata.info/__listinfo/pd-list</a>
<<a moz-do-not-send="true"
href="http://lists.puredata.info/listinfo/pd-list"
target="_blank">http://lists.puredata.info/listinfo/pd-list</a>>><span><br>
<br>
<br>
<br>
<br>
_________________________________________________<br>
<a moz-do-not-send="true"
href="mailto:Pd-list@lists.iem.at"
target="_blank">Pd-list@lists.iem.at</a>
<mailto:<a moz-do-not-send="true"
href="mailto:Pd-list@lists.iem.at"
target="_blank">Pd-list@lists.iem.at</a>>
mailing list<br>
UNSUBSCRIBE and
account-management -> <a
moz-do-not-send="true"
href="http://lists.puredata.info/__listinfo/pd-list"
target="_blank">http://lists.puredata.info/__listinfo/pd-list</a>
<<a moz-do-not-send="true"
href="http://lists.puredata.info/listinfo/pd-list"
target="_blank">http://lists.puredata.info/listinfo/pd-list</a>><br>
<br>
<br>
_________________________________________________<br>
<a moz-do-not-send="true"
href="mailto:Pd-list@lists.iem.at"
target="_blank">Pd-list@lists.iem.at</a>
<mailto:<a moz-do-not-send="true"
href="mailto:Pd-list@lists.iem.at"
target="_blank">Pd-list@lists.iem.at</a>>
mailing list<br>
UNSUBSCRIBE and account-management
-> <a moz-do-not-send="true"
href="http://lists.puredata.info/__listinfo/pd-list"
target="_blank">http://lists.puredata.info/__listinfo/pd-list</a>
<<a moz-do-not-send="true"
href="http://lists.puredata.info/listinfo/pd-list"
target="_blank">http://lists.puredata.info/listinfo/pd-list</a>><br>
<br>
<br>
</span></blockquote>
</blockquote>
</div>
<br>
</div>
</div>
<br>
<fieldset></fieldset>
<br>
</div>
</div>
<pre>_______________________________________________
<a moz-do-not-send="true" href="mailto:Pd-list@lists.iem.at" target="_blank">Pd-list@lists.iem.at</a> mailing list
UNSUBSCRIBE and account-management -> <a moz-do-not-send="true" href="http://lists.puredata.info/listinfo/pd-list" target="_blank">http://lists.puredata.info/listinfo/pd-list</a>
</pre>
</blockquote>
<br>
</div>
<br>
_______________________________________________<br>
<a moz-do-not-send="true" href="mailto:Pd-list@lists.iem.at">Pd-list@lists.iem.at</a>
mailing list<br>
UNSUBSCRIBE and account-management -> <a
moz-do-not-send="true"
href="http://lists.puredata.info/listinfo/pd-list"
target="_blank">http://lists.puredata.info/listinfo/pd-list</a><br>
<br>
</blockquote>
</div>
<br>
</div>
</blockquote>
<br>
</body>
</html>