A modified rough longest common subsequence algorithm for motif spotting in an Alapana of Carnatic Music

Melody in Carnatic Music is based on the concept of a raga. Characteristic motif is a signature melodic phrase that determines the identity of a raga. This paper addresses locating these motifs in an alapana, given a query motif. A two-step approach approach is employed. The first is to identify the location of snippets of phrases that exists in the Alapana. Next the conventional approach to the rough longest common subsequence algorithm to spot motifs is modified. In the modified algorithm a more appropriate measure of match is proposed. The algorithm is particularly relevant for short but good matches. The modification enables logical choices of empirical parameters. In this paper, the motifs that are chosen are also long compared to our earlier work. The modified RLCS algorithm reduces the number of false alarms from 130 to 94 and also performs better localization of motifs.