Re: [LAU] (Ardour) How to get rid of delay when recording ?

On Sun, 14 Feb 2016 14:43:01 +0000 Harry van Haaren <harryhaaren(a)gmail.com> wrote: A good definition is looming... Using the linux generic kernel as is, the following measurements were taken by connecting a single RCA cable from playback 3 to capture 6 and using qjackctl (which must be restarted before each run since jackd is launched from the command line). The goal now is to be able to have a delay that cannot be noticed without having xruns, crackling noise, i.e, while keeping processing running smoothly. There is no choice than to drop the delay below 5ms to get best response when playing. So this means 128. While 64 could be great, I am not so sure about overdoing it. If I understood correctly what will help in getting this are the low latency kernel, and a re-assignment of real time processing of IRQs. /usr/bin/jackd -T -ndefault -dalsa -dhw:M1010LT -r44100 -p512 -n2 configuring for 44100Hz, period = 512 frames (11.6 ms), buffer = 2 periods 1597.528 frames 36.225 ms total roundtrip latency extra loopback latency: 61 frames use 30 for the backend arguments -I and -O /usr/bin/jackd -T -ndefault -dalsa -dhw:M1010LT -r44100 -p256 -n2 configuring for 44100Hz, period = 256 frames (5.8 ms), buffer = 2 periods 829.529 frames 18.810 ms total roundtrip latency /usr/bin/jackd -T -ndefault -dalsa -dhw:M1010LT -r44100 -p128 -n2 configuring for 44100Hz, period = 128 frames (2.9 ms), buffer = 2 periods 445.529 frames 10.103 ms total roundtrip latency /usr/bin/jackd -T -ndefault -dalsa -dhw:M1010LT -r44100 -p64 -n2 configuring for 44100Hz, period = 64 frames (1.5 ms), buffer = 2 periods 253.529 frames 5.749 ms total roundtrip latency /usr/bin/jackd -T -ndefault -dalsa -dhw:M1010LT -r44100 -p32 -n2 configuring for 44100Hz, period = 32 frames (0.7 ms), buffer = 2 periods 157.529 frames 3.572 ms total roundtrip latency