how to align sliding window to extract features from multi modal timeseries data?

I have two datasets that are collected at different frequencies at the same time. One is recorded at 128Hz and another one is recorded at 512 Hz. I am trying to extract some features using the moving window technique but I have some problems.

1. Frequencies of both datasets are different.
2. the timestamp is in unix format and changes in nanoseconds. hence there won't be any match at the start and end of each second or minute.
3. one of the datasets is actually a little longer than the other by a few seconds.

is there any way I can align my window properly with respect to timestamp and calculate features? or if there is another way please suggest me.