Measuring When a Music Generation Algorithm Copies Too Much: The Originality Report, Cardinality Score, and Symbolic Fingerprinting by Geometric Hashing

Research on automatic music generation lacks consideration of the originality of musical outputs, creating risks of plagiarism and/or copyright infringement. We present the originality report —a set of analyses that is parameterised by a “similarity score”—for measuring the extent to which an algorithm copies from the input music. First, we construct a baseline, to determine the extent to which human composers borrow from themselves and each other in some existing music corpus. Second, we apply a similar analysis to musical outputs of runs of MAIA Markov and Music Transformer generation algorithms, and compare the results to the baseline. Third, we investigate how originality varies as a function of Transformer’s training epoch. Fourth, we demonstrate the originality report with a different “similarity score” based on symbolic fingerprinting, encompassing music with more complex, expressive timing information. Results indicate that the originality of Transfomer’s output is below the 95% confidence interval of the baseline. Musicological interpretation of the analyses shows that the Transformer model obtained via the conventional stopping criteria produces single-note repetition patterns, resulting in outputs of low quality and originality, while in later training epochs, the model tends to overfit, producing copies of excerpts of input pieces. Even with a larger data set, the same copying issues still exist. Thus, we recommend the originality report as a new means of evaluating algorithm training processes and outputs in future, and question the reported success of language-based deep learning models for music generation. Supporting materials (data sets and code) are available via https://osf.io/96emr/ .