Simple symmetrical wave RMS DEMO using awk. Post: 303002987

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Operating Systems OS X (Apple) Simple symmetrical wave RMS DEMO using awk. Post 303002987 by wisecracker on Wednesday 6th of September 2017 09:04:12 AM

09-06-2017

Registered User

Hi JM...
(Thanks for the reply.)
Apologies for any typos, and hope it is lucid enough.

Quote:

Originally Posted by jim mcnamara

It looks to me like you have a granularity problem. Four dots as a sample can fit a lot of functions, with intermediate datapoints from increased sampling rates you could then use fft to get good sine waves, for example.

You can code fft.c then call it using the system() function in awk. I think your awk supports that call.

A google for 'fft.c' got me 10 first page hits that looked respectably good. There are sites with an array of algorithmic variants to meet differing needs.

fft is gold standard for fitting data sampling output.

Apologies for the delay, I have not been around for a while. My triangle wave is more or less hypothetical as sampling a real time random triangle wave that......
1) starts at the 0 point,
2) is initially positive going,
3) has 4 samples, or any number of the same 4 samples,
......is close to impossible.
But a file CAN be so easily be created as shown in the single cycle version in the code.
Although I was aware of the errors that creep in when creating the RMS values I was NOT aware of this one off bizarre situation, (and could find nothing on the WWW about it), so after creating the simple code I made a point of there being a reference to this anomaly.

As the RMS value(s) are near the exact value(s) for that of a sinewave hence my point.

In the days of Debian 6 and PCLinuxOS 2009, (my two main OSes in those days), when '/dev/dsp' was available, recreating the waveforms through '/dev/dsp' would result in a triangle wave as the sound system interpolation was Linear, this was also true for some Windows machines of bygone days. I am not sure what interpolations are used in current OSes and sound systems but it sure looks trigonometric to me, so I would guess that a sinewave would be recreated as a result.

I am happy with the idea of the RMS code at this point but looking more towards True RMS but would probably need to rethink my approach.

But to re-iterate for others, be aware of this anomaly.

LBNL, for any FFT work needed, I would do it through Python and SciPy as the heavy lifting is done already, see previous uploads of AudioScope.sh for the AF Spectrum display...

Bazza...

Last edited by wisecracker; 09-06-2017 at 12:18 PM.. Reason: Modify for error...

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LEARN ABOUT DEBIAN

stk-demo

STK-DEMO(1)						      General Commands Manual						       STK-DEMO(1)

NAME

       stk-demo - Sound Synthesis Toolkit demo application

SYNOPSIS

       stk-demo Instrument [options]
       STKDemo

DESCRIPTION

       The  stk-demo  program demonstrates several of the algorithms that are built into the Sound Synthesis Toolkit (STK). The stk-demo is a com-
       mand line program, but it has a GUI frontend called STKDemo. Use STKDemo if you	want to try out the different synthesis algorithms  imple-
       mented in STK.

       The stk-demo program can be used to build your own synthesizer/sequencer combination. The program is listening to SKINI commands on stdin.

       Instrument can be one of the following:

       Clarinet,  BlowHole,  Saxofony, Flute, Brass, BlowBotl, Bowed, Plucked, StifKarp, Sitar, Mandolin, Rhodey, Wurley, TubeBell, HevyMetl, Per-
       cFlut, BeeThree, FMVoices, VoicForm, Moog, Simple, Drummer, BandedWG, Shakers, ModalBar, Mesh2D, Resonate, Whistle

       Simultaneous multiple output types are supported.  Likewise, simultaneous control input types are supported.   SKINI  formatted	scorefiles
       can be piped or redirected to stk-demo, though realtime control flags should be omitted when doing so. If the optional <file names> are not
       specified, default names will be indicated.  Each flag must include its own '-' sign.

OPTIONS

       -s RATE to specify a sample rate

       -n NUMBER
	      specifies the number of voices to allocate

       -ow <file name>
	      for .wav audio output file

       -os <file name>
	      for .snd audio output file

       -om <file name>
	      for .mat audio output file

       -oa <file name>
	      for .aif audio output file

       -or    for realtime audio output

       -ip    for realtime control input by pipe

       -is <port>
	      for realtime control input by socket

       -im    for realtime control input by MIDI,

       SEE ALSO

	      /usr/share/doc/stk-doc in the stk-doc package.

AUTHOR

       This manual page was written for the Debian project (but may be used by others).

								  august 13, 2004						       STK-DEMO(1)