Topic: Behringer UMC202HD
I was interested in the latency of the cheaper competitor and did a roundtrip-test via a physical loopback cable. Result at the beginning, the raw data at the end.
Output latency [1], tested with jack_iodelay at r=44100 Hz, p=64, n=2
Focusrite 2i2 gen2, 6.3 ms (ASYNC), 5.0 ms (SYNC)
Behringer UMC202HD, 7.7 ms (ASYNC), 6.3 ms (SYNC)
[1] Contains one assumption from the man page:
"Then, if you believe that the latency is equally distributed between the input and output parts of your audio hardware (extremely likely), divide the result by two and use that for input and output latency values."
Details
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UMC202HD (ASYNC):
488.684 frames 11.081 ms total roundtrip latency
extra loopback latency: 296 frames
use 148 for the backend arguments -I and -O
2636 ? SLl 0:16 /usr/bin/qjackctl
2646 ? SLsl 6:43 /usr/bin/jackd -p128 -dalsa -r44100 -p64 -n2 -D -Chw:U192k,0 -Phw:U192k,0 -i2 -o2
2707 ? SLl 3:21 jack_iodelay
Normal ASYNC playback: (n+1)*p -> 3*64=192 frames + 148 frames "extra loopback latency" = 340 frames -> 7.7 ms
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UMC202HD (SYNC):
430.684 frames 9.766 ms total roundtrip latency
extra loopback latency: 302 frames
use 151 for the backend arguments -I and -O
2944 ? SLl 0:02 /usr/bin/qjackctl
2949 ? SLsl 0:15 /usr/bin/jackd -S -p128 -dalsa -r44100 -p64 -n2 -D -Chw:U192k,0 -Phw:U192k,0 -i2 -o2
2964 pts/0 SLl 0:06 jack_iodelay
SYNC playback: n*p -> 2*64=128 frames + 151 frames "extra loopback latency" = 279 frames -> 6.3 ms
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2i2 gen2 (ASYNC):
366.715 frames 8.316 ms total roundtrip latency
extra loopback latency: 174 frames
use 87 for the backend arguments -I and -
2997 ? SLl 0:01 /usr/bin/qjackctl
3002 ? SLsl 0:10 /usr/bin/jackd -p128 -dalsa -r44100 -p64 -n2 -D -Chw:USB -Phw:USB -i2 -o2
3011 pts/0 SLl+ 0:04 jack_iodelay
Normal ASYNC playback: (n+1)*p -> 3*64=192 frames + 87 frames "extra loopback latency" = 279 frames -> 6.3 ms
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2i2 gen2 (SYNC):
312.715 frames 7.091 ms total roundtrip latency
extra loopback latency: 184 frames
use 92 for the backend arguments -I and -O
3035 ? SLl 0:01 /usr/bin/qjackctl
3041 ? SLsl 0:05 /usr/bin/jackd -S -p128 -dalsa -r44100 -p64 -n2 -D -Chw:USB -Phw:USB -i2 -o2
3050 pts/0 SLl+ 0:02 jack_iodelay
SYNC playback: n*p -> 2*64=128 frames + 92 frames "extra loopback latency" = 220 frames -> 5.0 ms
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