Suggestion (Bandpass Filter and Custom FFT Filter)

[Gale Andrews]

Nyquist plugins currently can't save their settings post session

They probably can now, but there aren't any Nyquist plugins yet that do.

Through Nyquist 4 or through the pluginsettings.cfg, do you mean?

Gale

[steve]

Through Nyquist 4.

[Videogamer555]

2.1.0

Version 2.1.0? The latest publicly released version is 2.0.6. Where can I get version 2.1.0?

[Robert J. H.]

2.1.0

Version 2.1.0? The latest publicly released version is 2.0.6. Where can I get version 2.1.0?

The next version is rather a "Milestone" release, thus the big jump from 2.0.6 to 2.1.0.
Just search for "Audacity Nightly Builds" with your favourite search engine.
The alpha builds are quite stable but you can instead wait for the official release (perhaps end of this month).

[Videogamer555]

I just tried a nightly build and I'm not sure exactly what the spectral filters do. I can tell they change the part of the spectrum I've selected, but I don't know exactly what they do. Any help on this would be nice.

[Gale Andrews]

I just tried a nightly build and I'm not sure exactly what the spectral filters do. I can tell they change the part of the spectrum I've selected, but I don't know exactly what they do. Any help on this would be nice.

It's not an official release obviously, but you can check out the documentation in the development Manual - http://manual.audacityteam.org/man/Spectral_Selection . Let us know if anything is unclear, and we could see if the text could be improved.

Please just realise that http://manual.audacityteam.org/man/ is not the Manual for 2.0.6, and that once 2.1.0 is released, http://manual.audacityteam.org/o/ will be the Manual for 2.1.0.

Gale

[Videogamer555]

I notice a problem in frequency selection in spectrogram in version 2.1.0. When you using the linear frequency display, for selecting the spectrum, it doesn't have the center frequency in the center. Instead it has it below the center. Turns out that in logarithmic frequency display, this frequency does correspond to what is in the center of the frequency upper and lower limit of what is selected. However, the selection mechanism should be aware of which spectrogram display mode you are in (linear or logarithmic frequency) and use the center frequency for that display mode as the center frequency of the selection. If you are using linear mode, it is because you want the literal center frequency to be the selected center frequency. If you are in logarithmic mode, it is because you want the the logarithmically centered frequency to be the selected center frequency.

Also, the spectrum edit filters should allow you to set the rolloff. Currently it is fixed at 6dB.

[steve]

I notice a problem in frequency selection in spectrogram in version 2.1.0. When you using the linear frequency display, for selecting the spectrum, it doesn't have the center frequency in the center. Instead it has it below the center.

That is correct. The spectral selection is a fixed order high, low or band pass filter, thus in the case of band pass the centre frequency is proportionally in the centre, thus it will appear in the centre in Spectrogram (log f) view and below the centre in linear Spectrogram view. This is basic physics.

[Gale Andrews]

I notice a problem in frequency selection in spectrogram in version 2.1.0. When you using the linear frequency display, for selecting the spectrum, it doesn't have the center frequency in the center. Instead it has it below the center.

That is correct. The spectral selection is a fixed order high, low or band pass filter, thus in the case of band pass the centre frequency is proportionally in the centre, thus it will appear in the centre in Spectrogram (log f) view and below the centre in linear Spectrogram view. This is basic physics.

I certainly agree what "center frequency" means will need properly explaining in the Manual. We may wish to remember the likely skill/knowledge level of the majority of our users.

The question I have is what proportion and what centre are we talking about for the centre line in the Spectrogram views. Are we talking about centre frequencies of band* and notch filters? Anyone can see that the center frequency in either log or linear view for example between a range of 2000 to 8000 Hz is below what some might expect (5000 Hz). Neither is it the geometric mean which I understand would be 4000 Hz.

I guess many people will ask this, so I'll be first.


Gale

[Paul L]

I notice a problem in frequency selection in spectrogram in version 2.1.0. When you using the linear frequency display, for selecting the spectrum, it doesn't have the center frequency in the center. Instead it has it below the center. Turns out that in logarithmic frequency display, this frequency does correspond to what is in the center of the frequency upper and lower limit of what is selected. However, the selection mechanism should be aware of which spectrogram display mode you are in (linear or logarithmic frequency) and use the center frequency for that display mode as the center frequency of the selection. If you are using linear mode, it is because you want the literal center frequency to be the selected center frequency. If you are in logarithmic mode, it is because you want the the logarithmically centered frequency to be the selected center frequency.

Also, the spectrum edit filters should allow you to set the rolloff. Currently it is fixed at 6dB.

As the implementer of spectral selection, I respond:

What you see in the display is by design and is not a "problem." The "center" frequency means the geometric, not arithmetic, mean of the top and bottom frequencies. That is a more useful quantity for purposes of filtering. If you do a notch filter with the multi-effect, the top and bottom frequencies are the approximate -3dB points, and the center line is the notched frequency, regardless of whether the scale of the display is linear or logarithmic.

This is not an exotic notion if you are accustomed the Equalizer tool, which uses a logarithmic scale of frequencies too.

Your suggestion about varying the rolloff frequencies is a good one, and it could be easily remedied by writing other versions of the Nyquist plug ins -- no need to change Audacity binaries. But I found that for practical use, I liked the effects to have no controls and so put up no dialogs that needed dismissing, so I could bind them to shortcut keys and use them often. If I want more rolloff, I can just repeat the effect on the same selection.