We are looking at ways to improve the content browsing, sorted by similarity with existing patterns would be cool, a quick way to find a “B-part” to a melody.
In terms of matching to a style or genre, there are a few things we can label, but it is already highly subjective for plain chord progressions, it is even harder to guess the emotion when you add the timing of the melody into the mix.
Exactly this. Instrumentation also has a big influence on the feeling.
I guess I don’t understand on what grounds Scaler then offers generous categorization of genres, styles, moods out of the box? If any resemblance of characterizing a tune is a moot point? I understand if there’s a technical challenge in reversing this process, but to argue that nothing is really definable?
As someone who is attempting to learn making socially acceptable music, and often gets the feedback “but that’s not how it sounds” (or it sounds like something else than I intended), there is clearly some criteria in listening that makes people judge what genre/style a tune is in. It may be hard to articulate for musicians who run on intuition, but the moment you are off in your melody, harmony, rhythm … (short of it being jazz) people will notice that you’re out of genre, or to the least in fusion.
The bass is one of the most important markers for the genre. On top of being harmonically relevant, it contains rhythmic information.
It is easy to identify a Funk bass from a Jazz or Rock one etc…
The expressions’ names are relevant but more evocative of a concept. This was doable because Davide knew the intent behind the melodic idea. He was able to capture the emotion with a single word really nicely.
But once adapted to another scale or playing at half or double speed it can give something different.
Chord progressions are pretty much the same. There is some universal feeling you can derive from hearing it played simply on a piano, but as soon as you throw some instrumentation and rhythms it is pretty subjective.
The same progression played with some Cuban instrumentation might go from sentimental to sexy (or not sexy at all if you don’t like this kind of music) etc…
However, and I think this is your point, in Cuban music, there are sad and joyful songs.
At the moment in Scaler, we would categorize them both under Cuban, if we like the sad progression we might make a “sad” progression in the relevant category but this is a human-based process.
Making sure that the MIDI you send is really sad is a bit more complex. But an interesting challenge 
I am definitely not the best person to help you there, but the lower side of the spectrum plays a big role. You can usually tell the style of music your neighbor listens to through the walls.
I have sometimes heard the bass is the most important, sometimes the drums, and more specifically the snare sound. It is something @davide might be able to help with.
I think my original comment had more to do with your first post - deriving feeling, mood, whatever from a detected chord progression. I stand by my opinion that there is nothing in a chord PROGRESSION that would necessarily give you that information. So many factors are involved from instrumentation right down to your memories that might be associated with any number of things in the song. Songs always affect moods, feelings, make you happy or sad. But playing 4 chords on a piano might not do it. Play those same 4 chords with a choir and its something different.
I never said there aren’t genres. There are many genres. There are many scales that are associated with different types of music because of the people of certain areas and how they went about creating the music they are known for - French, Spanish, Middle Eastern, et al. So it’s all very complex when the human brain is involved.
And of course it’s just my opinion and I could be completely wrong.
Personally, I always think that the classification according to music type is not necessarily the most accurate, but it must be the most accepted and comfortable.
The user can understand the meaning at the first time. There is no need to worry. Pop bass is only used for pop music. It is likely that everyone will also use it in hiphop and house.
If classified by music
If developers follow their own emotions, it may be difficult to communicate to all customers.
For example, if a doesn’t write a, it’s called “thin people”“
B is not called B, but “fat man”“
C doesn’t call C, call "open your mouth“
