So I have been doing some round trip latency testing on my system. And for jack_iodelay everything seems to work fine.
But after reading some old posts here that I saw after Gareus/x42 mentioned them over on Ardour forums, together with suggestions of skipping jack and running straight ALSA I wanted to run some more tests and tinker with settings a bit more.
My interface is a Scarlett 2i4 - running "stock kernel" that passes all the realtimeconfig checks and Ryzen 3700x.
So first off here are the best latencies I was able to achieve without xruns (purely in a test enviroment atm, not production tested):
Then for the ALSA testing. I have tried running alsa_delay https://www.venea.net/man/alsa_delay(1) but the numbers I am getting back isn't making any sense to me.First three are fairly stable, I have tested these in both Ardor and Carla with quite heavy loads.
JACK 48K 64 / 3 404.949 frames 8.436 ms total roundtrip latency
JACK 48K 64 / 4 420.907 frames 8.769 ms total roundtrip latency
JACK 48K 32 / 4 290.907 frames 6.061 ms total roundtrip latency
The following four I havent tested in any form in production but I suspect they would suffer some xruns.
JACK 96K 64 / 4 544.111 frames 5.668 ms total roundtrip latency
JACK 96K 128 / 4 732.111 frames 7.626 ms total roundtrip latency
JACK 192K 256 / 4 1429.617 frames 7.446 ms total roundtrip latency
JACK 192K 128 / 4 1077.617 frames 5.613 ms total roundtrip latency
alsa_delay hw:2 hw:2,0 48000 64 3 1 4
playback :
nchan : 4
fsamp : 48000
fsize : 64
nfrag : 3
format : S32_LE
capture :
nchan : 2
fsamp : 48000
fsize : 64
nfrag : 3
format : S32_LE
synced
0.000 frames 0.000 ms ?? Inv
0.000 frames 0.000 ms ??
0.000 frames 0.000 ms ?? Inv
5609.612 frames 116.867 ms ??
5609.612 frames 116.867 ms ?? Inv
56389.097 frames 1174.773 ms ??
56389.097 frames 1174.773 ms ?? Inv
43811.283 frames 912.735 ms ??
4301.472 frames 89.614 ms ?? Inv