JackAudio November 2020

jackaudio@lists.linuxaudio.org

6 participants
5 discussions

by Richard Hughes

jackaudio(a)lists.linuxaudio.org When I start qjackctl (1.9.16) on W10 and set portaudio interface to my USB soundcard, the Graph screen shows me my 2 input and output ports (plus MIDI) - but no other devices on my PC. How can I get the Graph or patchbay to show other devices such as my built in speaker, USB webcam/speakers or Voicemeeter, etc? Please help Richard Hughes

5 years

Distorted sound out of JACK-consumed programs

by Roberto Carraro

Hello, I'm new to audio production in Linux, so apologies in advance if I will use wrong terms and bad jargon. I'd like to record my guitars and bass, but I've found a problem which I think it can be JACK-related. I bought 2 USB audio interfaces, a 2-channel Behringer which I returned and a Focusrite Solo 3rd gen, which I'm testing right now. The issue that I have is with the programs that use JACK, like Guitarix and Reaper. It seems I can only get distorted sounds out of them and both have JACK as input source. Instead, Audacity, which lets me choose the hardware audio interface directly, lets me hear the sound of my instrument just fine. What I've tried so far: - my everyday Ubuntu 18.04 with low-latency patch: Guitarix and Reaper distorted audio and Audacity just fine - live AVlinux: Guitarix distorted audio and Audacity just fine - live Ubuntu Studio: Guitarix distorted audio and Audacity just fine Can someone please help? What else can I try? I'd like to stick with Ubuntu 18.04, as it is my main everyday desktop. Thank you. Roberto

5 years

DSP load

by skrzypoczt.gov13＠o2.pl

Hello I am using Jack on Windows machine. I am using the Jack to process audio in real time with few very CPU hungry VST plugins. I have a computer with 4 cores CPU but it is old machine. The playing software did not utilise the cores as it suposse to be. I have got an idea to use VST hosts, connect them and with Process Lasso to force the right core utilisation. And I have succeded the goal. All cores are utilised almost at the same level. My card is an USB interface with max buffer 4092 and ASIO driver. I have configured the Jack with maximum possible frames/buffers. With full set of VST plugins I am getting DSP load 100% what is total disater and in the same time CPU core utilisation in around 30%. Is there any way to solve that problem. Or it is just a kind of bottelneck connected with my USB interface or Jack? Regards

5 years

Latency compensation with multiple Jack-Instances connected by zita-njbridge

by Robin Rosenberger

Hello jack community, 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. 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: Main Jack, alsa backend using USB Interface (Presonus Audiobox USB96) Ardour Jack, dummy backend and Main Jack, alsa backend using USB Interface Ardour Jack, alsa backend using onboard audio (Intel 8 Series/C220 if it matters) Signal way in both cases for recording is: System in Main Jack - Zita to Ardour-Jack - Ardour - Zita to Main Jack - System out Main Jack So I never use the onboard physical connections. 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. So I get late recordings by 20ms from zita + the latency of the Main-Jack, that the Ardour-Jack doesn't know about. Is there any way to make this work? And why is the Ardour-Jack ignoring my extra latency settings? 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. Looking forward to your replies, stay safe and healthy! Best regards, Robin

5 years

vht - a live midi tracker

by Remigiusz Dybka

Hello, all I'd like to introduce you to a new midi tracker that I wrote. It's very minimalistic, a glorified repeater really. The main idea of the program was to have something to put between Carla and an external MIDI controller. selling points: - it only knows Jack - fast workflow - designed for live performance - irregular looping of tracks (have to see to believe) - funk mode (nice for triplets) - midi triggers - freewheel rendering Of course it is released under GPL3, otherwise I wouldn't be bothering you kind people. It compiles and runs on latest Ubuntu and Fedora (developed under Mint). Gnome app written in Python. The sequencing engine is in good ol' C (with jack being the only dependency). You can find the project at: https://github.com/rdybka/vht You can also check out: https://sourceforge.net/projects/vht for a current tarball and a deb for Ubuntu Hope someone besides me will find it useful Regards, Rem

5 years

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JackAudio November 2020