Hardware.decklink.enable = true;?

Help
1

Anyone had any luck with the Blackmagic Decklink cards please?

  hardware.decklink.enable = true;
  #https://github.com/NixOS/nixpkgs/blob/d7600c775f877cd87b4f5a831c28aa94137377aa/nixos/modules/hardware/decklink.nix

Maybe the URL moved?

[nix-shell:~/nixos/desktop/l]$ make
Hostnames match: l
sudo nixos-rebuild switch --flake .
warning: Git tree '/home/das/nixos' is dirty
building the system configuration...
warning: Git tree '/home/das/nixos' is dirty
error: builder for '/nix/store/ajn7gzfzmz7k8iz42h3ngbib9k4hyfnf-01-update-makefiles.drv' failed with exit code 1;
       last 17 log lines:
       >
       > trying https://aur.archlinux.org/cgit/aur.git/plain/01-update-makefiles.patch?h=decklink
       >   % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
       >                                  Dload  Upload   Total   Spent    Left  Speed
       >   0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
       > curl: (22) The requested URL returned error: 404
       > Warning: Problem (retrying all errors). Will retry in 1 second. 3 retries left.
       >   0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
       > curl: (22) The requested URL returned error: 404
       > Warning: Problem (retrying all errors). Will retry in 2 seconds. 2 retries
       > Warning: left.
       >   0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
       > curl: (22) The requested URL returned error: 404
       > Warning: Problem (retrying all errors). Will retry in 4 seconds. 1 retry left.
       >   0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
       > curl: (22) The requested URL returned error: 404
       > error: cannot download 01-update-makefiles from any mirror
       For full logs, run:
         nix log /nix/store/ajn7gzfzmz7k8iz42h3ngbib9k4hyfnf-01-update-makefiles.drv
error: 1 dependencies of derivation '/nix/store/l5qwz1591ysragak0m9n8mpi1sqgchgg-decklink-14.4.1a4.drv' failed to build
error: 1 dependencies of derivation '/nix/store/p2kbc49b3kbr6gcizfxbzpg5jf2xrqsx-linux-6.16.4-modules.drv' failed to build
error: 1 dependencies of derivation '/nix/store/cl28nr7807r0w12dyawa73xacfsspq61-nixos-system-l-25.11.20250830.d7600c7.drv' failed to build
Command 'nix --extra-experimental-features 'nix-command flakes' build --print-out-paths '/home/das/nixos/desktop/l#nixosConfigurations."l".config.system.build.toplevel' --no-link' returned non-zero exit status 1.
make: *** [Makefile:19: rebuild] Error 1

[nix-shell:~/nixos/desktop/l]$
2

Decklink does seem to work now.

hardware.decklink.enable = true;

I think I was missing blackmagic-desktop-video

{
  config,
  pkgs,
  ...
}:
{
  # $ nix search wget
  environment.systemPackages = with pkgs; [

    # Basic system tools
    psmisc
    vim
    curl
    wget
    tcpdump
    iproute2
    nftables
    #iptables
    pciutils
    usbutils
    iw
    wirelesstools
    #wpa_supplicant
    lldpd
    #snmp seems to be needed by lldpd
    net-snmp
    neofetch

    hostapd
    bridge-utils
    wireless-regdb
    linux-firmware

    # Network testing and performance tools
    iperf2
    flent
    netperf
    ethtool
    sysstat
    htop
    below
    iftop
    nethogs
    nload
    speedtest-cli
    mtr
    traceroute
    nmap
    tshark
    perf-tools
    linuxPackages_latest.perf

    clinfo
    lact

    rdma-core # ibv_devinfo, rdma
    pciutils
    libpciaccess

    # Blackmagic DeckLink
    blackmagic-desktop-video

    # Video tools
    v4l-utils    # v4l2-ctl
    ffmpeg-full

    # GStreamer with DeckLink support
    gst_all_1.gstreamer
    gst_all_1.gst-plugins-base
    gst_all_1.gst-plugins-good
    gst_all_1.gst-plugins-bad   # includes decklink plugin
    gst_all_1.gst-plugins-ugly
  ];
}

Some system info

[das@l2:~/nixos/desktop/l2]$ lspci | grep -i black
61:00.0 Multimedia video controller: Blackmagic Design DeckLink Mini Recorder


[das@l2:~/nixos/desktop/l2]$ lsmod | grep black
blackmagic_io        2531328  1
blackmagic            831488  0

[das@l2:~/nixos/desktop/l2]$ uname -a
Linux l2 6.18.3 #1-NixOS SMP PREEMPT_DYNAMIC Fri Jan  2 11:57:31 UTC 2026 x86_64 GNU/Linux


[das@l2:~/nixos/desktop/l2]$ gst-inspect-1.0 decklink
Plugin Details:
  Name                     decklink
  Description              Blackmagic Decklink plugin
  Filename                 /run/current-system/sw/lib/gstreamer-1.0/libgstdecklink.so
  Version                  1.26.5
  License                  LGPL
  Source module            gst-plugins-bad
  Documentation            https://gstreamer.freedesktop.org/documentation/decklink/
  Source release date      2025-08-07
  Binary package           GStreamer Bad Plug-ins
  Origin URL               Unknown package origin

  decklinkaudiosink: Decklink Audio Sink
  decklinkaudiosrc: Decklink Audio Source
  decklinkdeviceprovider: Decklink Device Provider
  decklinkvideosink: Decklink Video Sink
  decklinkvideosrc: Decklink Video Source

  5 features:
  +-- 4 elements
  +-- 1 device providers


[das@l2:~/nixos/desktop/l2]$

The ffmpeg doesn’t seem to include the decklink support, but gstreamer does

3

And the device

[das@l2:~/nixos/desktop/l2]$ ls /dev/blackmagic/io0 
/dev/blackmagic/io0

[das@l2:~/nixos/desktop/l2]$