[WIP] Alternative key detection algorithm

[daschuer]

This is a first prototype of a new key detection algorithm.

Highlights:

• Only reliable results, returns Invalid if no reliable detection is possible.
• improved reaction for short key changes.
• More Minor affinity
• Uses all notes with a 85 ms resolution, 1/32 Notes of a 160 BPM track. Originally we uses only one of eight notes. Drawback: 8 times more CPU.
• clean up chrome from off tune notes before detecting any patterns
• Use a combined scale and chord progression detection.
• recognize Gipsy/Melodic/Harmonic scales (currently returned as invalid)

Compare results:

Green Day - Good Riddance (Time Of Your Life)
(A easy pure G major)
before:

1 : "C" 655360
8 : "G" 6.07757e+06

now:

0 : "INVALID" 72832
8 : "G" 6.66419e+06

Alan Walker - Faded
(Changing Minor/Major key)
before:

7 : "F♯/G♭" 9.21459e+06
16 : "D♯m/E♭m" 131072

now:

0 : "INVALID" 191104
2 : "D♭" 425984
7 : "F♯/G♭" 2.52314e+06
16 : "D♯m/E♭m" 5.90234e+06
23 : "B♭m" 311296

REM - Losing my religion
(previously wrong detected)
before:

1 : "C" 655360
6 : "F" 884736
8 : "G" 1.60563e+06
15 : "Dm" 1.5401e+06
17 : "Em" 4.16154e+06
22 : "Am" 2.98432e+06

now:

0 : "INVALID" 166272
1 : "C" 2.42074e+06
3 : "D" 32768
6 : "F" 217088
15 : "Dm" 4096
17 : "Em" 3.64954e+06
22 : "Am" 5.33709e+06

Moby - Bodyrock (Olav Basoskis Da Hot Funk Da Freak Funk Remix)
(Undetectable because of sweeping tones)
before:

2 : "D♭" 950272
3 : "D" 4.9152e+06
6 : "F" 65536
8 : "G" 5.12653e+06
9 : "A♭" 819200
10 : "A" 655360
11 : "B♭" 360448
15 : "Dm" 262144
17 : "Em" 2.75251e+06
19 : "F♯m" 294912
22 : "Am" 327680
23 : "B♭m" 131072
24 : "Bm" 294912

now:

0 : "INVALID" 1.69312e+07
2 : "D♭" 12288
10 : "A" 12288

Michael Jackson - Man in the Mirror
(known for its famous key change from G to Ab)
before:

1 : "C" 720896
2 : "D♭" 4.37389e+06
7 : "F♯/G♭" 65536
8 : "G" 7.11066e+06
9 : "A♭" 1.14688e+06
16 : "D♯m/E♭m" 65536
21 : "G♯m" 655360
24 : "Bm" 98304

now:

0 : "INVALID" 6.53658e+06
2 : "D♭" 61440
8 : "G" 2.01523e+06
9 : "A♭" 3.53485e+06
12 : "B" 16384
17 : "Em" 1.85958e+06
24 : "Bm" 204800

[daschuer]

Christina Perri - Jar of Heards
(with a Melodic/Harmonic Minor bridge = Invalid)
before:

4 : "E♭" 1.06824e+07
10 : "A" 441600
13 : "Cm" 1.83501e+06
18 : "Fm" 32768

now:

0 : "INVALID" 2.37082e+06
1 : "C" 4096
4 : "E♭" 6.8649e+06
6 : "F" 163840
11 : "B♭" 1.06086e+06
13 : "Cm" 1.79814e+06
17 : "Em" 16384
20 : "Gm" 401408
23 : "B♭m" 4096
24 : "Bm" 299008

[uklotzde]

This patch is neither part of #2136 or #2137? I got lost.

[daschuer]

I am currently rebasing this on top of #2137

[daschuer]

Now rebased on the upstream fixes. And even better :-)

We can improve it more by a two pass analysis, forward and backward. And then sync key changes with phrases. Than a visualization in the overview widget will make the feature perfect.

For now we need a reasonable number of tests and identify miss detection.

How to handle key changes?

The Minor Major border within on scale (C<->Am) if fuzzy anyway and does not matter at all when looking for a compatible track. Even the far most common change to a neighbor scale in the circle of fifth is not that relevant, because of only one note of scale. So I think it OK to use only the major key for finding a compatible successor.

Problematic tracks are the rare tracks, recorded in a harmonic melodic and gypsy scale or tracks jumping in the circle of fifth like Michael Jackson's Man in the Mirror.

I propose not automatic to show a key for these tracks. I think it is in the responds of the DJ to set it or leave it blank. Alternative we may invent a new nomenclature for this. But I think it is only a negligible case.

Green Day - Good Riddance (Time Of Your Life)
(A easy pure G major)
before:

0 : "INVALID" 1.55864
8 : "G" 151.301

Alan Walker - Faded
(Changing Minor/Major key)

0 : "INVALID" 4.24054
2 : "D♭" 9.84526
7 : "F♯/G♭" 88.2358
16 : "D♯m/E♭m" 104.304
23 : "B♭m" 5.47991

REM - Losing my religion
(previously wrong detected)

0 : "INVALID" 3.4917
1 : "C" 16.7184
3 : "D" 0.278639
6 : "F" 3.06503
8 : "G" 0.650159
17 : "Em" 86.4711
22 : "Am" 157.617

Moby - Bodyrock (Olav Basoskis Da Hot Funk Da Freak Funk Remix)
(Undetectable because of sweeping tones)

0 : "INVALID" 383.37
2 : "D♭" 0.278639
10 : "A" 0.835918

Michael Jackson - Man in the Mirror
(known for its famous key change from G to Ab)

Debug [AnalyzerThread 0 #1]: 0 : "INVALID" 180.73
Debug [AnalyzerThread 0 #1]: 2 : "D♭" 0.743039
Debug [AnalyzerThread 0 #1]: 8 : "G" 17.0899
Debug [AnalyzerThread 0 #1]: 9 : "A♭" 38.0807
Debug [AnalyzerThread 0 #1]: 17 : "Em" 36.2231
Debug [AnalyzerThread 0 #1]: 18 : "Fm" 6.87311

Christina Perri - Jar of Heards
(with a Melodic/Harmonic Minor bridge = Invalid)

0 : "INVALID" 51.0133
1 : "C" 0.0853333
4 : "E♭" 171.264
11 : "B♭" 10.9227
13 : "Cm" 28.5013
17 : "Em" 0.0853333
20 : "Gm" 2.38933
24 : "Bm" 6.22933

[uklotzde]

Please rebase once again.

Is this a candidate for 2.3.0 or 2.4.0?

[Be-ing]

2.4. This is a big change that requires extensive testing and feedback.

[daschuer]

This is a 2.4.0 candidate. This needs to be tweaked and tested a lot. Currently it works better for some tracks and worse for others by taking more CPU. No good trade ...

[poelzi]

@daschuer is it possible to implement a confidence level and in cases the confidence is very low, try the other algorithms. Or if computation power does not matter, try all in parallel and calculate the most likely result with confidence in mind.

[daschuer]

Yes, that should be possible.

[daschuer]

I even consider to not annotate the track at all if the confidence it so low for both. This is even better than clutter the library with misleading key values.

[github-actions]

This PR is marked as stale because it has been open 90 days with no activity.