Test III - piano, chords and melodic content
This test involved a piece which was largely melodic, but had chords sketched out at the beginning of each bar. It’s a harder case for any system, but the sort of thing that I suspect @sseltenrych was asking about. It’s still monotimbral.
The files can be found at . | BTinternot as detection-nk
The midi file can be seen at ‘nk dabmg mid piano roll.jpg’ and as a mid at ‘nk dabmg mid’. The audio rendered file is at ‘nk dabmg.wav’.
The chords are pretty clear starting in each bar, but Scaler appeared to flunk the MDI detection - see ‘nk scaler.jpg.’ I may have done something wrong here, but for Scaler it’s “null pwan” as they used to say for Britain every year in the Eurovision song contest (fix!).
BIAB did better ‘nk bb.jpg’, picking up the sequence well enough to generate a pad backing.
Scaler Audio was fed the WAV file, and the results are shown in ‘nk audio detection.jpg’. Here it interpreted 7 out of the 8 bars. Where chords were detected, they were technically correct, but not necessarily the ones one might have chosen for a backing pad.
Feeding the WAV to deCoda produced ‘nk decoda.jpg’. It’s clear that it struggles with anything other than a triad interpretation. However, having said that deCoda has a real place in interpretation, as will be explained later
Test IV - piano melodic content with time variation.
This piece has been chosen as an example of a difficult file to analyse the chordal basis of melody, since there are mostly no chords within it.
The files can be found at . | BTinternot as detection-na (warning >40Mb)
Here, the solo notes defeated (as expected) Scaler’s MIDI detection (‘na scaler a.jpg’). BIAB made a reasonable, ironically probably because of a more naïve interpretation algorithm than Scaler.(‘na bb.pdf’).
Scaler Audio’s detection was more useful that the MIDI detection.
This example shows the issues for MIDI detection. This piece is about as simple as it can be in tune structure, and you can work out what it is, and accompany it in 30 seconds on a guitar using triads.
Part IV will contain some conclusions and some lessons learned by yorkeman in future.