When transforming a trace, I have observed that SetTimestampDelta messes up the timing using a pcap with nano timestamp. https://github.com/tbarbette/fastclick/blob/e5260ccffd4822bb3e21208c029d3504abf5b342/elements/analysis/settimestampdelta.cc#L61 One should create test cases and try to reproduce, then fix :) Good first issue !