Is this a good round trip latency test, and should I believe the results I'm getting? Windows 10/64
RTL test.pd

Here is my MOTU ultralight mk4 with its Main L output connected to Mic/Line 1 routed to Computer 1. It's interesting that Pd is set to the lowest delay possible for a 64 sample blocksize, but the measured latency is over 5X that. About 10 years ago, @katjav posted she was getting 1.5X on Linux.

And here is my Yamaha 01v96i with Monitor Out L connected to Channel 11 line in routed to bus 1/USB 1.

Finally, is it true that I could expect these latencies if I were to use Pd as a live signal processor provided my patch doesn't introduce latency normally (e.g. uses overlapped windowing for FFT resynthesis) and that Pd is not falling behind in audio processing?

the patch looks legit:

in Real Life latency occurs in every part: converter, port, driver / os, pd.

Linux can be set up to be very responsive on audio with realtime-priority ect. (how can this be done in Win?)

USB(1 and 2) introduces 1 or 2 ms of fixed latency.
RME pci(e) cards are the fastest hardware and drivers you can get (Linux too). Marian could be sameish (no Linux, last time I asked).

Today there are USB3 / Thunderbold, too - but don't know about their latency.

If you have headroom, 96k should be faster.

Because of the complexity of the chain, I would be surprised if latency would be same anytime, or to put it differently:
If the patch relies on it, I'd do the measurement each time on startup (with a free io channel or switching patchbay), even more in a live-concert. But empiricism on your system could disprove it, - and now I realize that this actually is your question, but no, I can not share experience on reliability of latency in Windows.

@jameslo which post of katjav are you referring to?
Recurrently there has been some conversation about latency on the pd-list.

@lacuna this one https://forum.pdpatchrepo.info/topic/7710/latency-on-output-and-input/3

yes, Katja's meter measures 1 sample latency additionally, so real latency is -1 sample.

here are threads of other forums:

https://forum.rme-audio.de/viewtopic.php?id=23459
linking to
https://web.archive.org/web/20160315074034/https://www.presonus.com/community/Learn/The-Truth-About-Digital-Audio-Latency

and an older comparision:
parts 1 2 3:
https://original.dawbench.com/audio-int-lowlatency.htm

https://gearspace.com/board/music-computers/618474-audio-interface-low-latency-performance-data-base.html

@jameslo Just for info.... since 2011 I have used the one distributed with Pd in doc/7.stuff/tools ... It's a bit fussy about the gain setting, but I have been assuming that it should be correct .
David.

@lacuna said:

Katja's meter measures 1 sample latency additionally, so real latency is -1 sample.

Does that imply you just downloaded Katja's meter? If so, how? All hurleur links are broken for me.

@whale-av Thanks, I wasn't aware of any of the tools in doc. Looking forward to studying their version.

yes, downloading patches works here.
...uploading... latency-tester.pd

and a version with simple fix: latency-tester2.pd
https://forum.pdpatchrepo.info/topic/13814/catch-would-like-to-set-the-name-programmatically/20

To find new adress of broken links to forum threads:
do an online search with "thread title site:pdpatchrepo.info"

The thread about this:
https://forum.pdpatchrepo.info/topic/11464/any-mirror-of-old-forum-puredata-hurleur-com