Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

Awesome Lists | Featured Topics | Projects

https://github.com/musnix/musnix

Real-time audio in NixOS
https://github.com/musnix/musnix

Last synced: 3 months ago
JSON representation

Real-time audio in NixOS

Awesome Lists containing this project

README 

        
# musnix



[![Check](https://github.com/musnix/musnix/actions/workflows/check.yml/badge.svg)](https://github.com/musnix/musnix/actions/workflows/check.yml)



Real-time audio in NixOS



## About



**musnix** provides a set of simple, high-level configuration options for doing real-time audio work in [NixOS](https://nixos.org/), including optimizing the kernel, applying the [`CONFIG_PREEMPT_RT`](https://rt.wiki.kernel.org/index.php/Main_Page) patch to it, and adjusting various low-level system settings.



## Basic Usage

Clone this project.



Add the following to your `configuration.nix`:

```nix

{

  imports =

    [ # ...

      /path/to/musnix/clone

    ];



  musnix.enable = true;

  users.users.johndoe.extraGroups = [ "audio" ];

}

```



To update musnix, run `git pull`.



Later sections of this document contain information about the various configuration options.



### Using musnix as a channel

As an alternative to the above approach, you can instead add musnix as a channel:



```

sudo -i nix-channel --add https://github.com/musnix/musnix/archive/master.tar.gz musnix

sudo -i nix-channel --update musnix

```



Add `` to `imports` in your `configuration.nix`:

```nix

{

  imports =

    [ # ...

      

    ];



  musnix.enable = true;

  users.users.johndoe.extraGroups = [ "audio" ];

}

```



To update musnix, run:

```

sudo -i nix-channel --update musnix

```



### Using musnix as a flake

As an alternative to the above approaches, you can also add musnix as a flake:



```nix

{

  inputs = {

    nixpkgs = { url = "github:NixOS/nixpkgs/nixos-unstable"; };

    musnix  = { url = "github:musnix/musnix"; };

  };

  outputs = inputs: rec {

    nixosConfigurations = {

      example-config = inputs.nixpkgs.lib.nixosSystem {

        system = "x86_64-linux";

        modules =

          [ # ...

            inputs.musnix.nixosModules.musnix

            ./configuration.nix

          ];

        specialArgs = { inherit inputs; };

      };

    };

  };

# ...

```



## Base Options



`musnix.enable`

* **Description:** Enable musnix, a module for real-time audio.

* **Type:** `boolean`

* **Default value:** `false`

* **NOTE:** This option must be set to `true` to use other musnix base options.

* **Details:** If enabled, this option will do the following:



  * Activate the `performance` CPU frequency scaling governor.



  * Set `vm.swappiness` to 10.



  * Set the following udev rules:

    ```

    KERNEL=="rtc0", GROUP="audio"

    KERNEL=="hpet", GROUP="audio"

    DEVPATH=="/devices/virtual/misc/cpu_dma_latency", OWNER="root", GROUP="audio", MODE="0660"

    ```



  * Set the following PAM limits:

    ```

    @audio  -       memlock unlimited

    @audio  -       rtprio  99

    @audio  soft    nofile  99999

    @audio  hard    nofile  99999

    ```



  * Set the following environment variables to default install locations in NixOS:

    * `VST_PATH`

    * `VST3_PATH`

    * `LXVST_PATH`

    * `LADSPA_PATH`

    * `LV2_PATH`

    * `DSSI_PATH`



  * Allow users to install plugins in the following directories:

    * `~/.vst`

    * `~/.vst3`

    * `~/.lxvst`

    * `~/.ladspa`

    * `~/.lv2`

    * `~/.dssi`



`musnix.alsaSeq.enable`

* **Description:** If enabled, load ALSA Sequencer kernel modules.  Currently, this only loads the `snd_seq` and `snd_rawmidi` modules.

* **Type:** `boolean`

* **Default value:** `true`



`musnix.ffado.enable`

* **Description:** If enabled, use the Free FireWire Audio Drivers (FFADO).

* **Type:** `boolean`

* **Default value:** `false`



`musnix.rtcqs.enable`

* **Description:** If enabled, install the [rtcqs command-line utulity](https://wiki.linuxaudio.org/wiki/system_configuration#rtcqs), which analyzes the system and makes suggestions about what to change to make it more audio-friendly.

* **Type:** `boolean`

* **Default value:** `false`



`musnix.soundcardPciId`

* **Description:** The PCI ID of the primary soundcard. Used to set the PCI latency timer.



  To find the PCI ID of your soundcard:

  ```

  lspci | grep -i audio

  ```

* **Type:** `string`

* **Default value:** `""`

* **Example value:** `"00:1b.0"`

* **NOTE:** If you have a USB sound card, this option is not useful.



## Kernel Options



**NOTE**: The following kernel options can be used without setting `musnix.enable = true;`



`musnix.kernel.realtime`

* **NOTE:** Enabling this option will rebuild your kernel.

* **Description:** If enabled, this option will apply the [`CONFIG_PREEMPT_RT`](https://rt.wiki.kernel.org/index.php/Main_Page) patch to the kernel.

* **Type:** `boolean`

* **Default value:** `false`



`musnix.kernel.packages`

* **Description:** This option allows you to select the real-time kernel used by musnix.

* **Type:** `package`

* **Default value:** `pkgs.linuxPackages_rt`

* Available packages:

  * `pkgs.linuxPackages_6_1_rt`

  * `pkgs.linuxPackages_6_6_rt`

  * `pkgs.linuxPackages_6_8_rt`



  or:

  * `pkgs.linuxPackages_rt` (currently `pkgs.linuxPackages_6_6_rt`)

  * `pkgs.linuxPackages_latest_rt` (currently `pkgs.linuxPackages_6_8_rt`)

  

## rtirq Options



**NOTES**:

* The following rtirq options can be used without setting `musnix.enable = true;`

* `musnix.kernel.realtime` must be set to `true` to use these options.



**musnix** can also install and run the [rtirq](http://wiki.linuxaudio.org/wiki/system_configuration#rtirq) script as a systemd service.



To see a list of options for using this feature, use the following command:



  `nixos-option musnix.rtirq`



To see a description of one of the listed options (in this case `enable`):



  `nixos-option musnix.rtirq.enable`



## Other Options



`musnix.das_watchdog.enable`

* **Description:** If enabled, start the [das_watchdog](https://github.com/kmatheussen/das_watchdog) service.  This service will ensure that a realtime process won't hang the machine.

* **Type:** `boolean`

* **Default value:** `true` if `musnix.kernel.realtime = true`, otherwise `false`



## Communication



* **IRC:** `#musnix` on [libera.chat](https://libera.chat/)



## More Information

* http://wiki.linuxaudio.org/wiki/system_configuration

* http://wiki.linuxaudio.org/wiki/system_configuration#rtirq

* http://subversion.ffado.org/wiki/IrqPriorities

* https://wiki.archlinux.org/index.php/Pro_Audio

* https://nixos.org/wiki/Audio_HOWTO