<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <meta name="Generator" content="Kopano WebApp v3.5.13.2531+1466.1"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>Latency compensation with multiple Jack-Instances connected by zita-njbridge</title> </head> <body> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">Hello jack community,<br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">I am trying to run two separate Jack instances, one for low latency monitoring using Carla as a plugin host and one for recording using Ardour with a higher buffersize for performance. The two jack servers are connected by zita-njbridge. </span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">Its working quite well so far, the issue is that I cannot compensate for the latency of the zita-bridges, 2*10ms. To my knowledge, jack provides latency information to Ardour, so i need to inform jack about the latency happening. I tried the following setups:<br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;"><br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">Main Jack, alsa backend using USB Interface (Presonus Audiobox USB96)<br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">Ardour Jack, dummy backend<br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">and<br /></span></p> <p style="padding: 0px; margin: 0px;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">Main Jack, alsa backend using USB Interface<br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">Ardour Jack, alsa backend using onboard audio (Intel 8 Series/C220 if it matters)<br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;"><br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">Signal way in both cases for recording is:</span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;"> System in Main Jack - Zita to Ardour-Jack - Ardour - Zita to Main Jack - System out Main Jack<br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">So I never use the onboard physical connections.<br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;"><br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">The first setup is problematic because the dummy backend doesn't have extra latency options, the latter seems to be ignoring the -I -O numbers in the Ardour-Jack, at least jack_iodelay tells me the same frame count no matter what I enter, which is not the case in the Main-Jack, where I can get it to 0 with the correct settings. </span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">So I get late recordings by 20ms from zita + the latency of the Main-Jack, that the Ardour-Jack doesn't know about.<br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;"><br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">Is there any way to make this work? And why is the Ardour-Jack ignoring my extra latency settings?<br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;"><br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">Even though I don't think it matters too much, I'm on Arch Linux, and using jack2 1.9.16-1 and Ardour 6.3-3.<br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">Looking forward to your replies, stay safe and healthy!<br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">Best regards,<br /></span></p> <p style="padding: 0; margin: 0;"><span style="font-size: 10pt; font-family: tahoma, arial, helvetica, sans-serif;">Robin<br /></span></p>  </body> </html>