So, for our purposes, pulseaudio is simply something that gets in our way. However, ALSA has since added multiplexing, and pulseaudio seems rather useless to me. I'm guessing that a long time ago, ALSA didn't offer support for multiple applications accessing a soundcard at the same time (multiplexing). Pulseaudio sits on top of ALSA and, in theory, adds some sort of value. If you get a "Channels count non available" message from aplay, then the format doesn't match. "Channels count non available" - The one tricky thing about aplay is that the WAV file format must match the exact format that the device expects. "Device or resource busy" - If you get a "Device or resource busy" message, that means someone else (like pulseaudio) is using the soundcard. $ sox -b 16 -n test.wav rate 44100 channels 2 synth 1 sine 440 gain -1 We'll use sox to generate a test WAV file. aplay is a simple audio player that can play WAV files. If not, then be sure to jot down the appropriate device name that you discovered, and use it where you see "hw:0" for the rest of this tutorial. Hopefully "hw:0" is all you need to know after looking at your device lists. It describes how to create your own device names and aliases which can be very helpful with multiple soundcards. "default" and "pulse") can be found in the nf file (usually found in /usr/share/alsa) and in the files in the directory. System-wide ALSA device names and aliases (e.g. If you leave subdevice or device off, it assumes 0. It appears that the general form is hw:card,device,subdevice. Note that there is also a subdevice level. That is the sound device that drives my HDMI port. The second is card 2, device 3, or "hw:2,3". That is a standard sound device that is connected to my speakers and headphone jack. The first is card 2, device 0, or "hw:2,0". **** List of PLAYBACK Hardware Devices ****Ĭard 2: Intel, device 0: ALC270 Analog Ĭard 2: Intel, device 3: HDMI 0 įrom this, we can see that I have two sound devices on my system. So, we need to figure out what audio device names have been assigned to which devices. You can run into trouble if your soundcard isn't where you think it should be. The various audio programs assume that they will be working with hw:0, but they all provide ways to change this. Usually, "hw:0" is the name of your soundcard. To uniquely identify each piece of audio hardware on a system, ALSA assigns them unique names. Many distros already have all the ALSA-related parts of the kernel built-in, so all you have to do is plug in your hardware and use it. It is made up of device drivers and other kernel modules that provide useful audio-related functions. ALSAĪLSA, the Advanced Linux Sound Architecture, is the part of the Linux kernel that talks to your sound-related hardware, like sound cards and MIDI interfaces. If you want a thorough understanding of Linux's support for MIDI, read on. If you are having trouble, come back here and go through this tutorial sequentially to find where the problem is. skip to the qjackctl section if you'd like to see the GUI approach. You can feel free to jump around if you'd like. Your system should now be ready to do everything described in this document. Ted adm cdrom sudo audio dip plugdev lpadmin sambashare To check whether you are running a low latency kernel, use uname: Installing a Low Latency KernelĪudio applications are time-critical, so they need a preemptible (low latency) kernel with a 1000Hz timer frequency. The next three sections cover these topics. Preliminariesīefore we get started, we need to take care of two things: It's still a good idea to read the whole thing as there are many helpful troubleshooting tips sprinkled throughout. If you would prefer a faster, more GUI approach, start with the " Preliminaries" sections, then jump to the qjackctl and Qsynth sections, then go back to the Virtual MIDI Keyboard section and read to the end. We will get to the GUI stuff near the end. The GUI can introduce new bugs, so it's more reliable to work with the command line tools. The reason for this is that it reduces the amount of software that is running which has two advantages: performance and reliability. This is a very command-line-intensive tutorial. This document has been tested with Ubuntu 22.04. This guide is intended to help ease the transition. The problem is that you've got to understand a lot about Linux to get started. Ted's Linux MIDI Guide Ted's Linux MIDI Guide
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