State-Based Transcription of Components of Carnatic Music

Automatic Carnatic Music (CM) transcription is an open problem in need of a standardized descriptive notation. The level of detail needed in a descriptive transcription makes it tedious to obtain ground truth by manual means. In this paper, we propose a novel state-based representation of the pitch curve motivated by CM components called constant-pitch notes and stationary points. We also propose a novel transcription technique that uses the Viterbi algorithm to estimate the states and quantized pitch-values. The proposed technique adheres best to rāga-notes compared to the existing critical-points technique and uniform quantization. In a listening test, clips synthesized from the proposed notation were rated significantly better (324 ratings, p < 0.001) than those from critical-points. Further, speed-halving based on state information best matches the actual, observed CM component-duration ratios without losing rāga-characteristics. Thus, the proposed transcription can be corrected manually to obtain ground truth and can enhance learning tools.