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Effect High pass filter with Q

https://forum.audacityteam.org/viewtopic.php?f=46&t=82801

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Effect High pass filter with Q

Posted: Sun Dec 28, 2014 12:31 pm
by юра00
Failed to overinstall defaults (cutoff frequency and q), after attempt to chahge the values error message appears or the effect doesn't work. The view of document:

;nyquist plug-in;version 1;type process;name "High Pass Filter with Q...";action "Applying High Pass Filter with Q...";info "High Pass Filter with Q by David R. Sky";control freq "Cutoff frequency" real "Hz" 1000 20 10000;control q "Filter q (resonance)" real "q" 1.00 0.00 5.00;; Highpass with Q, works on mono and stereo audio(if (arrayp s)(vector (highpass2 (aref s 0) freq q)(highpass2 (aref s 1) freq q))(highpass2 s freq q))

such as for High (or Low) Pass Filter, here it is easy to set new values. Other view of the document:

Code: Select all

;nyquist plug-in
;version 3
;type process
;preview enabled
;categories "http://lv2plug.in/ns/lv2core#LowpassPlugin"
;name "Low Pass Filter..."
;action "Performing Low Pass Filter..."
;author "Dominic Mazzoni"
;copyright "Released under terms of the GNU General Public License version 2"

;; lowpass.ny by Dominic Mazzoni
;; Modified by David R. Sky
;; Updated by Steve Daulton June 2012
;; Released under terms of the GNU General Public License version 2:
;; http://www.gnu.org/licenses/old-licenses/gpl-2.0.html .

;; To enable the Q control, remove one semicolon from the start of lines 18 and 32

;control rolloff "Rolloff (dB per octave)" choice "  6 dB,12 dB,24 dB,36 dB,48 dB" 1
;;control q "Filter quality (Q) for 12 dB rolloff" real "" 0.7071 .1 20
;control frequency "Cutoff frequency (Hz)" real "" 16000 1 20000

(cond 
  ((> frequency (/ *sound-srate* 2))
    (format nil 
           "Cutoff frequency is set at ~a Hz but must not~%~
           be greater than ~a Hz (half of the track sample rate)."
           frequency
           (truncate (/ *sound-srate* 2.0))))
  ((< frequency 1)
    (format nil
           "Cutoff frequency is set at ~a Hz~%but must be at least 1 Hz."
           frequency))
; ((= rolloff 1)(lowpass2 s frequency (max (min q 20) 0.1)))
  (T 
    (funcall 
      (nth rolloff '(lp lowpass2 lowpass4 lowpass6 lowpass8))
      s frequency)))
Please, correct!

Re: Effect High pass filter with Q

Posted: Sun Dec 28, 2014 4:30 pm
by Gale Andrews
юра00 wrote:Failed to overinstall defaults (cutoff frequency and q), after attempt to chahge the values error message appears or the effect doesn't work. [...] such as for High (or Low) Pass Filter, here it is easy to set new values.
So does this problem happen with http://wiki.audacityteam.org/wiki/Nyqui ... ter_with_q but not the High Pass or Low Pass?

I tried running Windows is Russian in today's build on Windows but did not see a problem. Please give an example of Cutoff and q values that cause the problem and give us the Debug output.

Are you inputting Cutoff values above half the sample rate? That gives a specific error in High Pass and Low Pass, but only a generic error in High Pass with Q.


Gale

Re: Effect High pass filter with Q

Posted: Sun Dec 28, 2014 4:53 pm
by steve
If you want to enable the Q setting, this is the code that you need:

Code: Select all

;nyquist plug-in
;version 3
;type process
;preview enabled
;categories "http://lv2plug.in/ns/lv2core#LowpassPlugin"
;name "Low Pass Filter..."
;action "Performing Low Pass Filter..."
;author "Dominic Mazzoni"
;copyright "Released under terms of the GNU General Public License version 2"

;; lowpass.ny by Dominic Mazzoni
;; Modified by David R. Sky
;; Updated by Steve Daulton June 2012
;; Released under terms of the GNU General Public License version 2:
;; http://www.gnu.org/licenses/old-licenses/gpl-2.0.html .

;; To enable the Q control, remove one semicolon from the start of lines 18 and 32

;control rolloff "Rolloff (dB per octave)" choice "  6 dB,12 dB,24 dB,36 dB,48 dB" 1
;control q "Filter quality (Q) for 12 dB rolloff" real "" 0.7071 .1 20
;control frequency "Cutoff frequency (Hz)" real "" 16000 1 20000

(cond
  ((> frequency (/ *sound-srate* 2))
    (format nil
           "Cutoff frequency is set at ~a Hz but must not~%~
           be greater than ~a Hz (half of the track sample rate)."
           frequency
           (truncate (/ *sound-srate* 2.0))))
  ((< frequency 1)
    (format nil
           "Cutoff frequency is set at ~a Hz~%but must be at least 1 Hz."
           frequency))
 ((= rolloff 1)(lowpass2 s frequency (max (min q 20) 0.1)))
  (T
    (funcall
      (nth rolloff '(lp lowpass2 lowpass4 lowpass6 lowpass8))
      s frequency)))
I note that in the code comment, the line that says:

Code: Select all

;; To enable the Q control, remove one semicolon from the start of lines 18 and 32
it should actually say;

Code: Select all

;; To enable the Q control, remove one semicolon from the start of lines 20 and 34
I shall correct that for the next Audacity release.

Re: Effect High pass filter with Q

Posted: Sun Dec 28, 2014 5:10 pm
by Gale Andrews
steve wrote:If you want to enable the Q setting, this is the code that you need
Did we decide not to make a note about that in the Manual pages for High Pass and Low Pass? I guess the problem may be explaining what Q does or why you might want to enable it.


Gale

Re: Effect High pass filter with Q

Posted: Sun Dec 28, 2014 5:28 pm
by steve
Gale Andrews wrote:Did we decide not to make a note about that in the Manual pages for High Pass and Low Pass? I guess the problem may be explaining what Q does or why you might want to enable it.
I think we decided not to mention it. Normally users will get best results with Q set to 1/2(2^0.5) (0.7071...). In those rare cases where users may want to use other Q settings, they will almost certainly know what "Q" is. We also agreed to retain "High Pass Filter with q" as an optional download (on the wiki).

Re: Effect High pass filter with Q

Posted: Sun Dec 28, 2014 5:53 pm
by юра00
1. Download additional plugin High pass filter with Q.
2. Try to set new value q: 0.88 instead of default 1., save changes in document.
3. Open audacity, Import file, try to apply the effect, but appears:

Copy from Show log.

21:54:47: Audacity 2.1.0-alpha-Dec 26 2014
21:54:47: Trying to load FFmpeg libraries...
21:54:47: Trying to load FFmpeg libraries from system paths. File name is 'avformat-55.dll'.
21:54:47: Looking up PATH environment variable...
21:54:47: PATH = 'C:Windowssystem32;C:Windows;C:WindowsSystem32Wbem;C:WindowsSystem32WindowsPowerShellv1.0'
21:54:47: Checking that '' is in PATH...
21:54:47: FFmpeg directory is in PATH.
21:54:47: Checking for monolithic avformat from 'avformat-55.dll'.
21:54:47: Error: Failed to load shared library 'avformat-55.dll' (error 126: не найден указанный модуль.)
21:54:47: Loading avutil from ''.
21:54:47: Error: Failed to load shared library '.dll' (error 126: не найден указанный модуль.)
21:54:47: Loading avcodec from ''.
21:54:47: Error: Failed to load shared library '.dll' (error 126: не найден указанный модуль.)
21:54:47: Loading avformat from 'avformat-55.dll'.
21:54:47: Error: Failed to load shared library 'avformat-55.dll' (error 126: не найден указанный модуль.)
21:54:47: Error: Failed to load FFmpeg libraries.
21:54:47: Error: Failed to find compatible FFmpeg libraries.

Re: Effect High pass filter with Q

Posted: Sun Dec 28, 2014 5:59 pm
by юра00
Attemt to change.
This problem not with High pass filter or Low pass filter, only for filters with q.

Re: Effect High pass filter with Q

Posted: Sun Dec 28, 2014 6:01 pm
by steve
Is "High Pass Filter with Q..." listed once in the list of effects, or twice?

Re: Effect High pass filter with Q

Posted: Sun Dec 28, 2014 6:03 pm
by steve
юра00 wrote:Attemt to change.
Your editor is messing up the lines.
It should look like this:

Code: Select all

;nyquist plug-in
;version 1
;type process
;name "High Pass Filter with Q..."
;action "Applying High Pass Filter with Q..."
;info "High Pass Filter with Q by David R. Sky"

;control freq "Cutoff frequency" real "Hz" 1000 20 10000
;control q "Filter q (resonance)" real "q" 1.00 0.00 5.00

;; Highpass with Q, works on mono and stereo audio

(if (arrayp s)
(vector (highpass2 (aref s 0) freq q)
(highpass2 (aref s 1) freq q))

(highpass2 s freq q))

Re: Effect High pass filter with Q

Posted: Sun Dec 28, 2014 6:08 pm
by юра00
In my editor it looks:

;nyquist plug-in;version 1;type process;name "High Pass Filter with Q..."
;action "Applying High Pass Filter with Q..."
;info "High Pass Filter with Q by David R. Sky"
;control freq "Cutoff frequency" real "Hz" 1000 20 10000
;control q "Filter q (resonance)" real "q" 0.88 0.00 5.00
;; Highpass with Q, works on mono and stereo audio(if (arrayp s)(vector (highpass2 (aref s 0) freq q)(highpass2 (aref s 1) freq q))(highpass2 s freq q))


It is listed once in the effects. I ask to correct problem with setting default values for the additional effect "High pass filter with q", not to enable q for usual effect High pass filter.
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