On Wed, 06 May 2020 12:00:02 -0400, time-nuts-requ...@lists.febo.com wrote: Re: time-nuts Digest, Vol 190, Issue 10 > > ------------------------------ > > Message: 6 > Date: Wed, 6 May 2020 07:00:51 -0700 > From: jimlux <jim...@earthlink.net> > To: Discussion of precise time and frequency measurement > <time-nuts@lists.febo.com> > Subject: [time-nuts] an interesting timing problem > Message-ID: <cfdf4164-1a45-a6e2-9538-4eb8b9f74...@earthlink.net> > Content-Type: text/plain; charset=utf-8; format=flowed > > Given that there's a lot more people spending time zooming, webexing, > teaming, skype, facetime, etc. these days, I'm curious if anyone has > figured out to *quantify* the issues of lag, desynchronization, etc. > > How would one go about instrumenting it (without access to the source > code or servers involved)? > > There's two areas of some interest to me: > 1) there's several studies that say that when voice and image aren't > perfectly synchronized, particularly if it's not a consistent delay, or > if there are gaps and jumps, that it is more stressful and creates a > cognitive workload that does not exist with actual in-person meetings > (the "why am I more tired after a day of telework than the real thing") > > 2) If you wanted to do group music playing or singing, relative timing > among the streams is critical. Is there a threshold where it all breaks > down? For instance, in an orchestra or choir, one has visual cues from > the conductor, but most people do not sing or play using the conductor > as a metronome triggering the next measure's notes. They also listen to > the players around them (or perhaps on the other side of the stage, some > 30-40 milliseconds late) > > > I can think of ways to "test" a given teleconferencing system (blinking > LEDs in a pattern, tone bursts on audio), but I think there's some > challenges in things like compression algorithms (do they have constant > latency?) and highly structured test signals might not measure the same > as actual video and audio. > > I will note that there are subjective difference among the various > tools, and there's differing effects from compression artifacts and > bandwidth/packet transport.
I recall digging into this some time ago for audio, in particular music, and found the answer in the Computer Music (meaning synthetic music) literature. There was a founding book, but I don't recall the details, and things have probably evolved since then. As I recall, if the time offset between instruments exceeded something like 20 milliseconds, the error became audible. Joe Gwinn _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.