Music Theory and Performance Analysis with Sebastian and Czerny

This talk will discuss two open source projects for using Python for music analysis. Sebastian focuses on music theory while Czerny focuses on performance (particularly keyboard playing).

Transcript

1. Music Theory and Performance Analysis with Sebastian and Czerny James Tauber @jtauber
2. The Idea The Components The Score The Performance The Recording Lilypond MIDI WAV Sebastian Czerny
3. Sebastian
4. Mathematical: Symbolic more than Numerical
5. repetitive hierarchical sequential + parallel factorable underspecified Modeling Music
6. Point of Departure [ {PITCH: 3, OCTAVE: 4, DURATION: 16}, {PITCH: 2, OCTAVE: 4, DURATION: 8} ]
7. Three Blind Mice mice = (seq1 * 2) + (seq2 + seq2a) + (seq2 + seq2b) + ((seq3 + seq3a) * 2) + (seq3 + seq3b) + seq1
8. Three Types of Sequence HSeq — Horizontal / Sequential VSeq — Vertical / Parallel OSeq — Offset-based
9. HSeq each element follows the previous concatenate(next_seq) repeat(count) __add__ __mul__ A = B * 2 + C
10. VSeq each element is coincident merge(parallel_seq) __floordiv__ A = B // C
11. OSeq factory function that returns a class using the given offset attribute and duration attribute def OSeq(offset_attr, duration_attr) has operators of both HSeq and VSeq
12. All Sequences __init__(*elements) __getitem__ & __len__ __eq__ & __ne__ transform(func) __or__ A = B | transpose(5) | reverse()
13. Three Types of Sequence HSeq — Horizontal / Sequential VSeq — Vertical / Parallel OSeq — Offset-based
14. Points handling underspecification with dictionaries unify(other) __mod__ {PITCH: 3, OCTAVE: 4} % {DURATION: 16}
15. Pitch note names two numbers or one? MIDI pitch Hewlett’s base-40 system my own system just have transforms for conversion
16. Tauber’s Pitch System D is 0 and each successor is a fifth higher modulo octave (e.g. A is 1, G is -1) semitone above is x-5 augment (semitone above, same letter) is x+7 modifiers: ((val+3)-((val+3)%7))/7 major scale: [tonic + i for i in [0, 2, 4, -1, 1, 3, 5]]
17. Lilypond from sebastian.lilypond.interp import parse seq1 = parse("e4. d c r") seq2 = parse("g4. f4 f8 e4.") seq2a = parse("r4.") seq2b = parse("r4 g8") seq3 = parse("c'4 c'8 b a b c'4 g8 g4") seq3a = parse("g8") seq3b = parse("f8")
18. Lilypond seq1 = parse("e4. d c r") [{'midi_pitch': 52, 'offset_64': 0, 'duration_64': 24}, {'midi_pitch': 50, 'offset_64': 24, 'duration_64': 24}, {'midi_pitch': 48, 'offset_64': 48, 'duration_64': 24}, {'offset_64': 96}]
19. MIDI library for parsing and generating MIDI files from sebastian.midi import write_midi write_midi.write("mice.mid", [mice])
20. Alberti common classical figuration of a triad a function from a triad to a sequence of notes great example of factorization and underspecification
21. Alberti def alberti(triad): return HSeq([ triad[0], triad[2], triad[1], triad[2] ])
22. Alberti root_triad = VSeq( Point(degree=1), Point(degree=3), Point(degree=5)) quaver = Point({DURATION_64: 8}) alberti_seq = OSequence( alberti(root_triad) * 16 | add(quaver) )
23. Alberti C_major = Key("C", major_scale) seq = alberti_seq | degree_in_key_with_octave(C_major, 5) | midi_pitch() write_midi.write("alberti.mid", [seq])
24. What’s Next? a lot more examples better use of MIDI input control over instruments in MIDI output nesting of sequences (for hierarchy) the notion of a “head” point
25. Sebastian
26. github.com/ jtauber/ sebastian
27. Czerny
28. What’s the Difference between the “Score” and the “Performance”
29. Positive vs Negative Differences study expression the performer is adding what errors were made? what inconsistencies or unevenness?
30. Representing the Performance a sequence of events MIDI?
31. Representing the Score just another sequence of events but this time desired events and with less information
32. C major scale ascending then descending over one octave represent as sequence of note + duration 60 8 62 4 64 4 65 4 67 4 69 4 71 4 72 8 71 4 69 4 67 4 65 4 64 4 62 4 60 8
33. MIDI Performance 4d54 6864 0000 0006 0000 0001 01e0 4d54 726b 0000 00cd 00ff 0308 2364 6566 6175 6c74 00ff 0413 5374 6569 6e77 6179 2050 6961 6e6f 2048 616c 6c00 ff58 0404 0218 0800 ff59 0200 0000 ff54 0521 0000 0000 00ff 5103 07a1 2089 6d90 3c4f 832b 903e 3a2c 903c 0081 3290 3e00 0390 403f 8137 9040 001f 9041 4181 3e90 4100 0790 4344 812d 9043 002a 9045 4d81 2090 4500 2690 473b 814b 9047 0018 9048 5583 2690 4800 0b90 473b 8148 9047 0006 9045 3b81 5990 433d 0490 4500 8132 9043 0022 9041 3981 2c90 4100 2090 4038 810e 9040 0035 903e 3081 1490 3e00 4190 3c42 831c 903c 0000 ff2f 00
34. Performance Events offset in “ticks” MIDI pitch velocity 0 velocity indicates note off 1261 60 79 1688 62 58 1732 60 0 1910 62 0 1913 64 63 2096 64 0 2127 65 65 2317 65 0 2324 67 68 2497 67 0 2539 69 77 2699 69 0 2737 71 59 2940 71 0 2964 72 85 3386 72 0 ...
35. Performance Events convert from note start + note end to just start + duration 1261 60 79 471 1688 62 58 222 1913 64 63 183 2127 65 65 190 2324 67 68 173 2539 69 77 160 2737 71 59 203 2964 72 85 422 3397 71 59 200 3603 69 59 221 3820 67 61 182 4036 65 57 172 4240 64 56 142 4435 62 48 148 4648 60 66 412
36. We Want to Diff 1261 60 79 471 1688 62 58 222 1913 64 63 183 2127 65 65 190 2324 67 68 173 2539 69 77 160 2737 71 59 203 2964 72 85 422 3397 71 59 200 3603 69 59 221 3820 67 61 182 4036 65 57 172 4240 64 56 142 4435 62 48 148 4648 60 66 412 60 8 62 4 64 4 65 4 67 4 69 4 71 4 72 8 71 4 69 4 67 4 65 4 64 4 62 4 60 8 vs
37. Want to Diff to diff, you must first align alignment is a dynamic programming problem generally relying on notion of scoring the relative cost of adding, deletion or changing items the “change” score can be very domain specific Needleman-Wunsch algorithm
38. “Change” Score just consider note value: +1 if same, 0 if different or: +1 if same, +0.5 if a tone or semi- tone apart, 0 if more duration? wrong octave?
39. Result ((60, 8), (1261, 60, 79, 471)) ((62, 4), (1688, 62, 58, 222)) ((64, 4), (1913, 64, 63, 183)) ((65, 4), (2127, 65, 65, 190)) ((67, 4), (2324, 67, 68, 173)) ((69, 4), (2539, 69, 77, 160)) ((71, 4), (2737, 71, 59, 203)) ((72, 8), (2964, 72, 85, 422)) ((71, 4), (3397, 71, 59, 200)) ((69, 4), (3603, 69, 59, 221)) ((67, 4), (3820, 67, 61, 182)) ((65, 4), (4036, 65, 57, 172)) ((64, 4), (4240, 64, 56, 142)) ((62, 4), (4435, 62, 48, 148)) ((60, 4), (4648, 60, 66, 412))
40. Visualizing Mistakes
41. Czerny
42. github.com/ jtauber/ czerny
43. Music Theory and Performance Analysis with Sebastian and Czerny James Tauber @jtauber