Still plan to do testing but have several questions about what rules the 'Divide Drum Track' actually uses to split things up.

For reference see Blakes Tech Talk - https://youtu.be/0c3xYobr5_o?t=1735

And Bad Mister's article about the topic - https://yamahasynth.com/learn/montage-series-synthesizers/divide-drum-track-in-os-v3-0-mastering-montage/

I'm not a drummer but I follow the basic concept, and see the benefits, that Blake and the article present about creating separate tracks/parts for various types of drums. It makes it a lot easier to exert better control over the mixing and any effects (panning, etc) when you can deal with one type at a time.

This paragraph from BM's article sets the stage:

Concept: Normally, you record your basic drum groove using a single KIT, on a single Track. “Divide Drum Track” applied to that track will then analyze what you played and automatically EXTRACT the different components and split them (dissolve) to separate tracks, using Tracks 9-16 and Parts 9-16. It assigns the same Drum Kit used to all eight Parts so there will be no difference overall in how it sounds, initially. The idea is so that you now have separate tracks for your different drum components.

But I'm trying to understand how a drum part/track that might have up to 73 different different types of sounds gets mapped to only 8 new parts.

The paragraph that follows that one above is this:

It is not strictly isolating just one Drum per Track, necessarily. It puts things together that you would work on together. For example, the HiHat Closed, HiHat Pedal and HiHat Open all arrive on the same dissolved Track – this makes sense as these are worked on as a set. The Tom-toms and the Crash Cymbal arrive on the same dissolved Track – this makes sense when working on a Fill-in phrase. The snare, sidestick, and snare roll will all arrive on the same Track, and so on. Your mileage may vary depending on the Type of Kit you have selected and the layout of its instrument data, but generally, it looks to isolate instruments of the same kind or instruments you would likely work with together.

That makes me think that the 'divide' operation expects certain types of drums to specifically be on certain keys. Then it could use a mapping table to identify notes/keys for the different drum types and parcel them out to a separate track.

But it raises several questions to me:

1. how is the actual drum 'type' determined? Are specific keys in the C0 to C6 range always mapped to specific drum types. If so, what happens if you use that key to a different sound?

2. only 8 new parts are created so are some of the 73 drum keys/notes C0 to C6 discarded if the limit is exceeded? Or if more than 8 drum types are detected do some of the 8 new parts have the notes from more than one drum type?

3. There are three HiHats mentioned above. Is there some internal flag that actually identifies them as 'HiHats'?

The 'Divide Drum Track' operation appears to work even using an AWM2 part:

1. create Init Normal (AWM2)

2. create a new pattern and play a simple set of notes: F3,G3,A3,B3,C3,B3,A3,G3,F3

3. save the pattern and performance with name 'aPattern'

4. play the pattern and it plays a loop of the notes above

5. use 'Divide Drum Track' and select 'track 1' 

6. specify 'aPattern2' as new performance name

The result is a new performance with the identical part 1 and new parts 9-16.

1. load 'aPattern' two operformance

2. go to the pattern screen and select Part 16

3. play any key on the keyboard and the above sequence of notes will play

Note that there were no drum parts and there were no 'drum' keys.

But it created 8 new parts and puts all the notes from track 1 of the pattern into the new part 16. So it didn't just blindly map notes in the range C0 to C6 to separate parts. It treated all the notes as if they were the same 'type'. Or it looked at the part type and determined it wasn't a drum part but an AWM2 part and classified the notes at type 'AWM2' so put them in the same target part.

Does anyone have any thoughts about what is actually going on under the covers? Is there some defined set of 8 drum types that are used for the mapping?