improving music mood classification using lyrics, audio and social tags

CHAPTER 2: LITERATURE REVIEW
2.1 MOOD AS A NOVEL METADATA TYPE FOR MUSIC
Traditionally music information is organized and accessed by bibliographic metadata such as
title, composer, performer and release date. However, recent MIR studies have pointed out that
traditional bibliographic information of music is far from enough for effective MIR systems
(Futrelle & Downie, 2002; Byrd & Crawford, 2002; Lee & Downie, 2004). Futrelle and Downie
(2002) called for both descriptive and contextual metadata; Lee and Downie (2004) pointed out
the importance of associative and perceptual metadata (e.g., use, mood, rating, etc.).
In recent years, as online music repositories are becoming more popular, new non-traditional
metadata have emerged in organizing music. Hu and Downie (2007) explored the 179 mood
labels on AllMusicGuide 3 and analyzed the relationships that mood has with genre and artist.
The results show that music mood, as a new type of music metadata, appears to be independent
of genre and artist. Therefore, mood, as a new access point to music information, is a necessary
complement to established ones.
2.2 MOOD IN MUSIC PSYCHOLOGY
In the information science and MIR community, mood is a novel metadata type and thus
there are many fundamental issues on music mood remaining unresolved. For example, there is
no terminology consensus on the very topic in question: some researchers use “music emotion,”
some others use “music mood” to refer to the affective aspects of music. On the other hand, there
3 http://www.allmusic.com, a popular metadata service that reviews and categorizes albums, songs and artists.
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