Triple-based analysis of music alignments without the need of ground-truth annotations

Abstract

The goal of music alignment methods is to temporally align different versions of the same piece of music. These methods are typically evaluated by comparing the computed alignments to given ground-truth annotations. Creating such annotations is usually very labor intensive. For many musical pieces, especially in classical music, there exists a multitude of different recordings. In this work, we investigate whether an evaluation of music alignment algorithms can be performed without ground-truth annotations when at least a triplet of recordings of the same piece of music is available. The main idea is to align the time points of a fixed reference version, in a circular way, back through a second and third version by using their pairwise alignments. A triple error is then computed by comparing these time points with their circularly aligned version. In this paper, we formalize the idea of the triple error and discuss its potential and limitations. We present typical examples for the triple error and compare it to the pairwise alignment error based on ground-truth. Furthermore, we present a case study to indicate the potential of the triple error to analyze alignments and to compare different alignment methods without the need of ground-truth annotations.