Thanks for this. Yesterday I did more digging around and found a paper by Jerome Barthélemy &al Figured Bass and Tonality Recognition, which went well beyond what I was looking for. And then I discovered that the keyword is "Pitch Spelling", obvious when I think about it, people would have been trying to do this for turning MIDI files into notation. In this connection I found stuff like David Meredith, Pitch Spelling Algorithms and Joshua Stoddard &al WELL-TEMPERED SPELLING:A KEY-INVARIANT PITCH SPELLING ALGORITHM. One of these papers reported finding more errors in the original documents than errors made by the algorithm! But so far no actual code I could call, and the algorithms look fairly heavy. Having realized that anyone trying to do MIDI->Notation will be wanting to do this, I was thinking some more digging may be worth while looking under MIDI->Notation converters. Your idea would be much quicker both to implement and execute, and could be enough for my purposes. I'll do a bit more digging... Richard BTW I did a bit of re-working of your ReBar script; I hope I used the latest version, as I couldn't locate (all?) the bug reports where you submitted it - I used the version in git.
On Sun, 2011-07-10 at 20:03 -0400, Daniel Wilckens wrote: > Hi Richard, > > I've only had time to look at the mailing list every once in a while > recently but I did see your post asking for an algorithm to check for > misspelled enharmonics. This could be tough, as e.g. dimished fourths > would be rare but not forbidden. Here are a few thoughts of mine on > this, though you probably already considered something along these > lines. Unless you want to go with something really fancy AI-wise, I'd > probably go with an interactive script that stepped through the score > looking for unlikely interval spellings in consecutive notes (that > would be diminished fourths like D to A#, augmented seconds like C to > D#, augmented thirds, diminished thirds, etc.) and ask you to decide > whether you really meant it to be written that way or whether you want > the script to fix it for you to the other spelling. > > To sketch an algorithm for this, each pitch-spelling would be given an > integer (which I'll call its index) representing its distance in number > of perfect 5ths from C. So, C would be 0, G would be 1, F would be -1, > .. C# would be 7 and Db would be -5, etc... Then the script would flag > something as unlikely if the index of consecutive notes differed by more > than 6 (6, being a tritone, could go either way: C to F# or C to Gflat > are both OK). This is a pretty feeble-minded AI but should catch most > errors of the sort you'd encounter I would think. > > For individual chords, you could check if the set of indices of the > tones comprising the chord fit into a set of 6 consecutive integers, i.e. > > | MinIndex-MaxIndex | <= 6. > > So a D7 chord, D, F#, A , C, would translate as the indices 2, 6, 3, 0, > which easily fits into the set 0, ... 6, so it's OK. (This would > wrongly flag augmented 6th chords, since Aflat to F# would be indices -4 > and 6, which is an interval of 10. That's one reason to require the > user to check each proposed fix. Augmented chords would be flagged > also, but probably the user can deal with each one since they're not all > that common until later.) Consecutive chords should be flagged as > suspicious, I would say, if their combined set of pitches has | Min - > Max | of 9 or more, since a cadence in a minor key involve the third of > the dominant and the third of the root which have an interval of > diminished fourth. These tolerances could be tweakable. > > I can't even think of any plausible fancier algorithm. Somehow you > could take into consideration not just the current and preceding > note/chord, but perhaps the next one also. There are some methods out > there that might be worth looking into if you were really gung-ho, like > Hidden Markov Models which some people have tried to write automatic > piano-fingering generators with, but they take a lot of tweaking and > "learning". Hope this helps! > > -Dan > _______________________________________________ Denemo-devel mailing list [email protected] https://lists.gnu.org/mailman/listinfo/denemo-devel
