Recently I had the idea to categorize my digital music library with mood tags.
Thinking about these moods, I figured that it's not so easy to come up with a complete list that covers all possible emotional impressions.
Some example categories could be "happy", "sad", "mellow", "aggressive", "uplifting", "melancholic", "joyful", etc.
Are there any classification systems that categorize music by mood? What are they based on? Have you used them, and why?
Some very famous pieces of music have started with a mood description written on the sheet music by the composer.
Some other have become the perfect example of a given mood (Appassionata, Pathetic for Beethoven)
You could start with the MIREX vocabulary clusters
Some people use research from psychologist about human moods such as Robert Thayer's (not restricted to music).
Classifiying music is a very active research subject, especially these days for commercial reasons. Every internet music platform wants to propose and sell tracks to their users by different recommendation systems. Classifying (if possible automatically) music tracks becomes a way to feed such a recommendation system.
If people work with clusters, it is because they encountered difficulties in predicting reliably appartenance of music to finer divisions.
To refine these mood clusters, what you can do is take all the adjectives in each cluster, their synonyms and try to see if you can either group some of them or draw limits between them based on simple concepts.
Companies like Pandora are known to have designed a multi-criteria classification of music pieces and song, constructed first by humans as the Music Genome Project. Their model is quite sophisticated and could be of great interest to a composer.
Other usual (commercial) suspects (without restricting themselves to mood classification or contiguity) are Last.frm, MusicBrainz, Spotify, Musicovery, Aupeo, Stereomood, ... Members of these organizations sometimes write research articles about what they do. Many universities labs do research on this (US MIT, Sony, French IRCAM, ...). There are alternative systems, some based on color like Ghost.
Also if you want to have non standard descriptive phrase for music pieces, you can enjoy Satie's french humour, like in "Morceaux en forme de poire".
Just to add information, indian classical music is based on the concept of Raga ("color"), a hard to define concept because it doesn't exists in western music as it is, but we can say it's the melodic system used in ICM, the modal framework. Raga generates Bhavas ("moods") and these moods generate Rasa ("essence") and it's the essence of an emotion that the performed art generates. Thus, different ragas ("modes") invoke particular rasa (the essence of a emotion or mental state). One can say that raga is the colors which paint particular moods and the experience of the essence of a emotion on the listener's mind.
This company builds its business around defining the mood of music. It's important because their goal is to deliver a system which can help you tune the music to the mood you desire.
I don't know it they already have an English intro on their site, I couldn't find it. But maybe that is because I get automatically relocated to the Dutch one.
Anyway, maybe their way of categorizing music according to mood can give you some ideas.
EDIT: From what I could gather on this list, they have following classes:
Comfortable, dynamic, intense, intimate, mystical and relaxing. Each of these is then further subdivided according to genre.
More specifically, genres tend to draw their boundaries at mood shifts, and often newer subgenres will have mood/emotion as part of their name.
I love using this particular photo as evidence.
Others have made me aware that many genres are named differently, and I must now backtrack a bit and offer that genres, at their basis (bases? basises?), get their names from differences in the sound of the music, but I'll stick to my original point that at least some genres do use emotional feel as a weak qualifier.
