Quoting conrad berhörster <beat.siegel.v...@gmx.de>:

maybe this helps
http://welltemperedstudio.wordpress.com/code/lemma/

lemma looks cool. I will definitely give it a try as soon as I get my daw back from the repair shop...

and take a look at
impro-visor
http://www.cs.hmc.edu/~keller/jazz/improvisor/

I also worked with impro-visor a lot. Basically it has too many features for my requirements. I just want an easy-to-use tool to provide a playback track for practice sessions for those of us that lack the skill or the extra hands to accompany themselves on the piano during practice. I remember the playback quality to be very good, though. I never got to use all the melody-centered functionalities, it's a different use-case really. That's also one of my design goals - focus on the central requirement, keep everything out that's not absolutely necessary, make it as easy to use as possible, and in the end really focus on the quality of the output (i.e. the music that can be heard).

And maybe you can explain a little bit about your ideas about the
pattern-less approach

Happy to, though it might get a bit longish from here on. Bear with me. My reasoning goes like this: Take the bass part of a very simplistic straight 4-beat groove. In a fictional pseudo-pattern-defining-format you may specify something like this:
 -) Play the bass note of the chord on beat 1.
 -) Play the bass note of the chord on the off-beat after 2.
 -) Play the bass note of the chord on beat 3.
 -) Play the bass note of the chord on the off-beat after 4.
This will sound fine on straight-forward one-chord-per-bar tunes. Even if you change chord every two beats it will sound reasonably good. But what of bars with a chord change on every beat, such as happens often in Jazz, especially in turnarounds and the like? The bass player will miss every other chord! Sure, you could add a rule like
 -) In addition, play the bass note of the chord at every chord change.
assuming your pseudo-pattern-defining-format allows this. But then the notes on the off-beats defined earlier will not sound too good. A real life bass player would in such turnaround bars probably play a single note on every chord change and leave out the off-beat notes. Or consider off-beat chord changes, also a common thing. Just think about what a typical pattern definition will make of them, and what a real player would play. Still, it's possible to express all this in a pattern definition. But always provided the engine reading the pattern files supports it! And I think that sooner rather than later you reach the point where understanding the syntax of a sufficiently powerful pattern format and actually writing good patterns in it is not that much easier than programming in any well-structured contemporary programming language. Bottom line: I think everyone able to define patterns so complex that they actually sound really good is just as able to program them given a well-structured framework to work in. What you gain by actually programming a groove is that you are no longer limited by the abilities of the pattern interpreter, but have the full expressive power of the programming language at your disposal. Random elements, variations in timing and volume to make it sound more human, even the occasional wrong note, all that is possible without any changes to the engine itself. BTW, the same holds for the voicing of chords. Consider the ugly but simple progression D7 C9 Bb6. By defining for the bass to
 -) Play the root note of the chord in octave #3
will give you a not only ugly but also quite unrealistic jump of a seventh up at the last change. It gets worse if the voicing of the pianists right hand just builds the chords up from the root. Playing the above progression with all the chords in root position will not only violate a lot of voicing rules, it will also sound pretty crappy. A real-life pianist would probably play all three chords with the D at the bottom, or maybe even move up through D E F or something similar. Actually programming such rules is doable, defining them in a declarative fashion is much much harder. So how does this actually work? At the lowest (and most convenient) level you just define your Groove as a number of Players, each representing typically one instrument. In your Player you have two hook methods, one that gets called once for every bar and one that gets called once for every chord change. Within these methods you define (actually you program) what notes should be added to the final music. For that you have not only methods to actually add notes to the track, but also a (hopefully still growing) number of convenience methods, for example to get the proper notes for the current chord from a voicing engine or to get not only the current chord but also the previous and next chord(s) (for example to program cool walking bass lines you need the full context) as well as their suggested voicings, etc. In addition you can do basically everything that can be programmed. In the most simple case, programming in that layer is not harder than defining patterns. The simple pattern from above would look something like this:
 void createEvents(Bar bar) {
   addNote(getVoicing(getChordAt(0.0)).get(0), 0.0, 1.0, 0.35);
   addNote(getVoicing(getChordAt(0.375)).get(0), 0.375, 1.0, 0.12);
   addNote(getVoicing(getChordAt(0.5)).get(0), 0.5, 1.0, 0.35);
   addNote(getVoicing(getChordAt(0.875)).get(0), 0.875, 1.0, 0.12);
 }
The difference is that you are not limited anymore. You can even skip the convenience layer and directly implement your own Player object, in which you receive a list of music information (Bars, Chord changes, Volume changes, Tempo changes), an assigned MIDI channel number and the set MIDI resolution, and must return simply an arbitrary list of MIDI events.

To everyone who made it this far: Thanks for listening ;-)

Mike

--
Michael Niemeck
Krausegasse 4-6/3/6
1110 Wien
mich...@niemeck.org
+43 1 9417017
+43 660 9417017


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