18 Nov
2017
18 Nov
'17
12:55 p.m.
El 18/11/17 a les 00:50, Markus Grabner ha escrit:
Am Mittwoch, 15. November 2017, 15:33:29 CET schrieb
Xavier Mendez:
It'd be nice if they also supported synchronizing MIDI ports, but that's
TODO for now. For the rest, IMO they're pretty much ready to go.
(shameless self-citation) I made jack_lsync that
does this, both
jack_lset and jack_lsync can be found in:
https://github.com/jmendeth/jack-tools/tree/latency-tools
Excellent, I was just
starting to implement a similar tool myself, you saved
me a lot of work! Dropping in two instances of your client in the capture and
playback path precisely aligns the round-trip pulses in my Ardour test setup
(even in the pathological case that both signals are recorded into the same
track).
I vote for adding these tools to the Jack example clients. What do you think
about this?
BTW, one question regarding the "coefficient" parameter: I thought this should
always be "1" (align to maximum latency), but didn't notice any difference
when leaving its default value 0.5 (align to center), both variants gave
correct results. How does this coefficient affect the behaviour of your client?
The coefficient has no effect when all ports' input latency has the same
minimum and maximum (i.e. one port [ 337 337 ] and the other [ 867 867
]). That's expected most of the time.
If one port had [ 523 1024 ] latency you'd probably be doing it wrong,
but jack_lsync still has to deal with it, and that's what the parameter
is for. If coefficient was 0, lsync would assume 523 latency when
calculating the delays to apply, if it's 1 it'll assume 1024, and if
it's the default it'll just take the mean of min & max, and assume 773.
So it's only there for those strange cases that should ideally never happen.
PS: If you want to use alsa_out or alsa_in, note this bug which may make
them report wrong playback/capture latencies in some cases
https://github.com/jackaudio/tools/pull/8
Xavi
Thanks & kind regards,
Markus
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