Harmony separation

Mel-RoFormer replaces heuristic non-overlapping bands with overlapping mel-band subbands and reports better separation than BS-RoFormer for vocals, drums, and other stems on MUSDB18HQ.

BS-RoFormer uses band-split spectrogram features plus RoPE Transformers; the SDX23 system ranked first in the music source separation track and a smaller version reported 9.80 dB average SDR on MUSDB18HQ.

The SDX23 music demixing paper documents robust MSS benchmarks, listening tests, and that the best system improved over the prior challenge by more than 1.6 dB SDR on MDXDB21.