[PD] measuring time with sample accuracy

[Alain de Cheveigne']

I would like to measure the time of  occurrence of waveform events 
(for example from adc~) with  sample resolution.   In other words, I 
would like to record at what sample index an event such as a 
threshold crossing  occurred.  The aim is to time events on various 
inputs relative to each other with sample accuracy.

I may be wrong, but I don't  think things like vline~, timer or 
realtime can give me this accuracy.  What I have in mind is something 
like threshold~, but that outputs the index at which a 
threshold-crossing event occurred.

Does such a thing exist?

Alain