We have just released a preprint of our latest work on time-varying delay estimation on the arXiv. This work uses the same all-pass filter principle as our previous delay estimation work but implements an adaptive filter to estimate the filter coefficients eliminating the need to have all of the data in advance.

The paper is available here: Adaptive All-Pass Filter Paper and on arXiv:2101.02406, code to implement the filter is available on GitHub: LAP Delay Estimation Repository.

Update March 19, 2021: This paper has now been published in IEEE Signal Processing Letters doi:10.1109/LSP.2021.3065889.