Re: [LAD] Real-time plotting of audio/ oscilloscope.

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To: <fons@...>
Cc: <linux-audio-dev@...>
Date: Thursday, June 17, 2010 - 5:38 pm

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On Thu, Jun 17, 2010 at 10:41 AM, wrote:

> On Thu, Jun 17, 2010 at 04:09:08AM -0400, Jeremy wrote:

Well I'm interested in plotting two things:

1. A single buffer of the audio
2. The autocorrelation (and selected peak) of that same buffer.

This means about a thousand samples per window (although the goal is to
increase it). I'm only looking at periodic signals, or at least that's all
I care about, so I can change the frequency until it's a harmonic of the
buffer size. On the other hand, the autocorrelation is almost constant, so
that is also interpretable by me, even when refresh rate.

Now, assuming a 60 Hz refresh rate (which is what I believe my monitor has),
and a buffer size of 1024 pixels, that would be a throughput of 61440
samples per second. More than the 48000 sampling rate. So it seems that
drawing every sample *is* a reasonable request. But obviously a lower
refresh rate would also satisfy my needs.

Thanks everyone for the suggestions of programs to look at. It looks like
I'm going to separate the drawing into another thread, although I am a
little bit confused as to why that is necessary. I'll probably copy
something from jack.scope or meterscape, as they seem closest to what I
want.

Jeremy

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On Thu, Jun 17, 2010 at 10:41 AM, <fons@kokkinizita.n=
et
> wrote:

On Thu, Jun 17, 2010 at 04:09:08AM -0400, Jeremy wrote:

> Yes, I'll bet that's my problem. Is it because writing to the =
screen is high

where

Plotting a waveform with 48kHz samples per second is not that
difficult and it doesn't require HW acceleration or esoteric
hardware.

But *what* do you want to see ? Of one thing you can be sure:
the information contained in 48k samples per second will
overload the visual parts of your brain. If the waveform
is more or less cyclic for some time, you can set a trigger
level and display small fragments - that is what a scope
is doing. In the other case the only thing that makes much
sense is display longer fragments, and then the only info
you get from this the amplitude envelope.

Ciao,

--
FA

O tu, che porte, correndo si ?
E guerra e morte !
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Well I'm interested in plotting =
two things:1.=A0 A single buffer of the audio2.=A0 The autocorr=
elation (and selected peak) of that same buffer.This means about a =
thousand samples per window (although the goal is to increase it).=A0 I&#39=
;m only looking at periodic signals, or at least that's all I care abou=
t, so I can change the frequency until it's a harmonic of the buffer si=
ze.=A0 On the other hand, the autocorrelation is almost constant, so that i=
s also interpretable by me, even when refresh rate.

Now, assuming a 60 Hz refresh rate (which is what I believe my monitor =
has), and a buffer size of 1024 pixels, that would be=A0 a throughput of 61=
440 samples per second.=A0 More than the 48000 sampling rate.=A0 So it seem=
s that drawing every sample *is* a reasonable request.=A0 But obviously a l=
ower refresh rate would also satisfy my needs.

Thanks everyone for the suggestions of programs to look at.=A0 It looks=
like I'm going to separate the drawing into another thread, although I=
am a little bit confused as to why that is necessary.=A0 I'll probably=
copy something from jack.scope or meterscape, as they seem closest to what=
I want.

Jeremy

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Messages in current thread:
Re: [LAD] Real-time plotting of audio/ oscilloscope., Johannes Kroll, (Fri Jun 18, 5:10 pm)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Damien Zammit, (Fri Jun 18, 12:53 am)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Robin Gareus, (Thu Jun 17, 2:23 pm)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Peter Nelson, (Thu Jun 17, 7:21 am)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Jeremy, (Thu Jun 17, 5:38 pm)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Jörn Nettingsmeier, (Thu Jun 17, 7:29 pm)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Paul Davis, (Thu Jun 17, 8:28 pm)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Nick Copeland, (Thu Jun 17, 8:53 pm)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Robin Gareus, (Fri Jun 18, 1:13 am)
Re: [LAD] Real-time plotting of audio/ oscilloscope., David Olofson, (Fri Jun 18, 12:37 am)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Will Light, (Thu Jun 17, 5:59 pm)
Re: [LAD] Real-time plotting of audio/ oscilloscope., James Morris, (Thu Jun 17, 7:57 am)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Philipp Überbacher, (Thu Jun 17, 8:11 am)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Jeremy Jongepier, (Thu Jun 17, 1:36 pm)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Ralf Mardorf, (Thu Jun 17, 6:25 am)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Gene Heskett, (Thu Jun 17, 2:30 pm)
Re: [LAD] , Mike Cookson, (Thu Jun 17, 8:04 am)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Ralf Mardorf, (Thu Jun 17, 7:26 am)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Paul Davis, (Thu Jun 17, 10:41 am)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Gene Heskett, (Thu Jun 17, 2:48 pm)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Ralf Mardorf, (Thu Jun 17, 7:33 am)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Ralf Mardorf, (Thu Jun 17, 6:41 am)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Gene Heskett, (Thu Jun 17, 2:27 pm)
Re: [LAD] Real-time plotting of audio/ oscilloscope., Ralf Mardorf, (Thu Jun 17, 6:43 am)