The problem with a lookup table is that is assumes a short finite list of
chord we need to support, but that's not the case. There are abitrarily
many chords to support - eg, Dbma9#5sus. But sure, the parsing already
reduces everything to a basic quality (major, minor, etc) and extension, so
a lookup table for that much is not totally unreasonable. Not sure it buys
you anything over doing it algorithmically, thiugh.
On Tue, Mar 15, 2016 at 6:14 PM David Cuny <davidfc...@gmail.com> wrote:
> > I am speculating/thinking aloud and at this point I am beginning to
> > believe it is overengineering,
>
> Yes - you can get away with a *lot* with keyboard accompaniment. People
> generally aren't going to complain if voices drop out, skip, or even leap
> every now and then.
>
> As you suggested, use a simple lookup table to get the chordal notes
> (using half-steps from the root) such as this:
>
> maj: [0, 4, 7]
> min: [0, 3, 7]
> sus4: [0, 5, 7]
> min7: [0, 3, 7, 10]
> 7: [0, 4, 7, 10]
> maj7: [0, 4, 7, 11]
> 9: [4, 7, 10, 2]
> 11: [7, 10, 2, 5]
>
> Add the MIDI note of the root, and you get the MIDI note numbers of the
> chordals.
>
> To "voice" the chord, just choose an upper bound for the chord (MIDI 76
> works for me), and then shift the notes into place:
>
> // force each note to lie an octave below the maximum
> for each note in notes
> while note < highest_note-12
> note += 12;
>
> That's all you need to get surprisingly good results.
>
> -- David
>
>
> On Tue, Mar 15, 2016 at 3:55 PM, Tobia Tesan <tobia.te...@gmail.com>
> wrote:
>
>> On 15/03/2016 23:29, Marc Sabatella wrote:
>>
>> > Indeed, voice leading is good to optimize, but we also need good
>> > voicings for the initial chord of a section, where there is no
>> > previoia chord to base on.
>>
>> I am speculating/thinking aloud and at this point I am beginning to
>> believe it is overengineering, but to get a globally optimum selection
>> of voicings, including the first chord, I don't think it would be
>> *terribly* difficult to cast the problem like this:
>>
>> * have a lookup table with a standard library of voicings, 4 or 5 per
>> chord, in a fixed range (thus avoiding the "drfting problem")
>> * have a matrix of penalties for each pair of adjacent voicings, defined
>> to be as the sum of the broken rules, with weights (e.g. +1 for a step,
>> +5 for a leap, +100 for something Very Bad, etc, as outlined in David's
>> message)
>> * chose an optimal combination of chords to minimize the sum of penalties
>>
>> I think a modern machine can be made to solve it reasonably fast for a
>> sequence of ~100 chords.
>>
>> > Also, except for jazz, I think most people would probably expect the
>> > same chord symbol to always produce the same voicing, which is
>> > something else to consider.
>>
>> Are you thinking "pop music"?
>> Because that crowd can probably be satisfied with a standard library of
>> open chords, wouldn't they?
>>
>> Good night :)
>>
>> --
>> Tobia Tesan
>> <tobia.te...@gmail.com>
>> <sip:tobia.te...@ekiga.net>
>> "If you don't fail at least 90 percent of the time, you're not aiming
>> high enough."
>> -- Alan Kay
>>
>>
>>
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