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Help test this Android tuner app

Morne

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Recently I was playing around with adding some filters to a tuner app on Linux: https://accordionists.co.uk/viewtopic.php?f=3&t=5525
In short, the goal was to enable the tuner to distinguish octave notes and to remove unwanted notes from the display if you know exactly what you are looking for.
Im posting a new thread because I dont want the technical details of that earlier thread to pollute the discussion.

The original developer, Bill Farmer, has now ported those filters over to the Android version of the tuner app (All credit goes to him - I didnt touch the Android code). It has not yet been released officially, but he has created an experimental release for us to test. Download and install Tuner-filters.apk from here: https://github.com/billthefarmer/tuner/releases/tag/v1.20
(You might have to set your phone to allow installation from Unknown sources.)
Once this is released officially it will be available on the F-Droid app store here:
https://f-droid.org/en/packages/org.billthefarmer.tuner/

You can read more about the app here:
https://github.com/billthefarmer/tuner/wiki

What changed?
The main additions are under Settings (cog icon) -> Note filter. Thatll give you two kinds of filters:
  • Fundamental: When using the existing Multiple notes along with the Audio filter and Downsample settings, this filter will try to remove all the spurious notes and show you only the most likely one. You might still end up with spurious octaves below and above the notes you are interested in, which is where the next filter comes in.
  • Note filters: When you enable this, you can select the specific notes and the octaves you are interested in seeing.
The Note filters can be used for:
  • Removing spurious octaves (with or without the Fundamental filter)
  • Hiding some notes when playing chords
  • Ignoring wrong notes/harmonics/overtones when playing a single note

How to test?
When testing bass notes/octaves, enable Multiple notes, Audio filter and Downsample. See what you get - there should be a lot of spurious notes. Then enable the Fundamental note filter. This should narrow down the displayed notes to the correct note name (e.g. C only). If you get extra octaves below and above the expected octaves, use additional Octave filters to set only the correct ones.
When testing treble octaves, it might not be necessary to enable Audio filter, but you will probably need to enable Downsample. But do play around with the settings to see what ends up showing you the correct octaves.

The goal is to see whether the implemented DSP algorithms along with the filters will show values that correspond to those that you know are correct on your accordion. E.g. if you tuned it yourself by some other system, or had it perfectly tuned recently.

How else can you help?
If you speak Spanish, Portuguese, Hungarian or Japanese, have a look at the translations and if anything looks funny, post it here or if you are technical, do a pull request on GitHub.

If youre experienced in DSP, you can also have a look at the downsampling algorithm to see if it performing optimally. This is important for bass detection and for figuring out multiple octaves.

Suggestions?
If you have any other suggestions - for features or usability - open an issue on GitHub or post it here.

Why bother?
This app is free, both in price and in being open source. If these changes work as expected, then this will be a really useful app for accordion tuning since most other tuner apps typically only do a single note. Itll give you some of the multi note detection features that you might only find in tools like Dirks Tuner, but without all the other bells and whistles that you dont need, and without the hefty price tag.
 

debra

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I checked out the new app. (I have tried this before and it worked well, except that it was unable to show me for instance an L and M reed to check their relative tuning.)
What worked before still works in the new app. The note and octave filters work as well. Nice feature for when the tuner picks up the wrong octave or spurious notes that do not exist (but that sound through intermodulation). Checking out an LM register (or notes played in octaves) still does not work. Filtering out the 7th octave to see the tuning of C8 still does not work. (C8 is actually quite difficult for all tuners except for Dirk's accordion tuner, even though the visualization shows the mic is capturing the signal.)
The UI could still use some improvement. There is a left arrow to go back from the settings page to the tuner but when configuring one of the settings (like the note filter) there is no left arrow to go back to the settings page. Sorry, can't resist. I taught HCI for many years...
 

Morne

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debra post_id=55917 time=1520410650 user_id=605 said:
Checking out an LM register (or notes played in octaves) still does not work.

Did you try that with the Downsample setting turned on?
When I did some tests with my Linux version (which is the same logic) it was possible to see all 3 notes when playing LMH, together or individually, on my Morino. Admittedly, the notes were a little out of tune, but it was able to show sub 1 cent difference between the 3 octaves. Heres where it happened: Ill check this out again with the Android app.

debra post_id=55917 time=1520410650 user_id=605 said:
Filtering out the 7th octave to see the tuning of C8 still does not work. (C8 is actually quite difficult for all tuners except for Dirks accordion tuner, even though the visualization shows the mic is capturing the signal.)

This is likely my original design mistake. I originally implemented octaves 0-7 because of the information on Wikipedia about a piano accordions range. But CBAs obviously have larger range (up to octave 8). If you enable the octave filter currently youll never see C8 because the filter will only show what you have selected. I will ask the developer to add octave 8, which might solve this issue.

debra post_id=55917 time=1520410650 user_id=605 said:
The UI could still use some improvement. There is a left arrow to go back from the settings page to the tuner but when configuring one of the settings (like the note filter) there is no left arrow to go back to the settings page. Sorry, cant resist. I taught HCI for many years...

By all means, if you notice anything else let us know. I didnt even pay attention to that because I always use the phones back button.
 

Morne

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debra post_id=55917 time=1520410650 user_id=605 said:
Checking out an LM register (or notes played in octaves) still does not work. Filtering out the 7th octave to see the tuning of C8 still does not work. (C8 is actually quite difficult for all tuners except for Dirks accordion tuner, even though the visualization shows the mic is capturing the signal.)

Ive tested the latest code (not in an APK yet) and it can now detect that C8. It even managed to show me C6+C7+C8 on my Morino VI. Here are some screenshots from my phone. I was using Multiple notes + Downsample + Note filter: C + Octave filter: 6, 7, 8:
Pull:

Push:


(Yes, it can do with a bit of tuning on those high notes, but thats a different story.)

It even shows me all four octaves when playing the E bass on master. Here Im using the same settings, but with Audio filter enabled too.


I realise those two scenarios are a bit extreme, but if it can handle that then it shouldnt have a problem with fewer octaves and with pitches more in the middle. Having said that, since I dont have any accordions that were recently made perfectly in tune, its hard for me to tell what it would show in such a scenario. If you use the settings I used and it still ends up showing only the lowest note, then I believe its too in tune for the algorithm to separate the octaves. But since in my examples it does show separate octaves that are cent-wise almost equally out of tune, I would imagine that it should still show you multiple notes.
 

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debra

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Morne post_id=55944 time=1520457806 user_id=1217 said:
...
Ive tested the latest code (not in an APK yet) and it can now detect that C8. It even managed to show me C6+C7+C8 on my Morino VI. Here are some screenshots from my phone. I was using Multiple notes + Downsample + Note filter: C + Octave filter: 6, 7, 8:
...

That sounds promising.
Ill give it another go later.
 

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