v4l2

flake.nix

@@ -306,6 +306,7 @@
             fi
           '';
 
+          v4l2-play = pkgs.callPackage ./pkgs/v4l2-play {};
           device-mon = pkgs.callPackage ./pkgs/device-mon {};
           #pdoc-docs  = (pkgs.callPackage ./pkgs/pdocs.nix {}).pdocs;
           #pdoc3-docs = (pkgs.callPackage ./pkgs/pdocs.nix {}).pdocs3;

pkgs/v4l2-play/default.nix

@@ -0,0 +1,60 @@
+{
+  lib,
+  pkgs,
+}:
+
+let
+  runtimeInputs =  with pkgs; [
+    ffmpeg
+    v4l-utils
+    alsa-utils
+    gnome.zenity
+    lxterminal
+  ];
+in
+
+pkgs.stdenvNoCC.mkDerivation (finalAttrs: {
+  name = "v4l2-play";
+  meta.mainProgram = "v4l2-play";
+
+  nativeBuildInputs = with pkgs; [
+    makeWrapper
+    copyDesktopItems
+  ];
+
+  dontUnpack = true;
+  dontBuild = true;
+  dontConfigure = true;
+
+  installPhase = ''
+    runHook preInstall
+
+    mkdir -p $out/bin
+    cp ${./script.sh} $out/bin/v4l2-play
+    chmod +wx $out/bin/v4l2-play
+
+    substituteInPlace $out/bin/v4l2-play \
+      --replace-fail \
+        "#!/usr/bin/env nix-shell" \
+        "#!${pkgs.runtimeShell}"
+
+    wrapProgram $out/bin/v4l2-play \
+      --prefix PATH : ${lib.makeBinPath runtimeInputs}
+
+    runHook postInstall
+  '';
+
+  desktopItems = pkgs.makeDesktopItem {
+    name = "v4l2-play";
+    desktopName = "View video device";
+    exec = "v4l2-play";
+    keywords = [
+      "elgato"
+      "passthrough"
+      "v4l2"
+      "video4linux2"
+      "capture card"
+    ];
+  };
+
+})

pkgs/v4l2-play/script.sh

@@ -0,0 +1,93 @@
+#!/usr/bin/env nix-shell
+#!nix-shell -i bash -p ffmpeg v4l-utils alsa-utils gnome.zenity lxterminal
+set -euo pipefail
+
+#if [[ -z ${_IS_IN_GUI:-} ]]; then
+#    exec lxterminal --command "_IS_IN_GUI=1 $(printf "%q" "$(realpath "$0")")" &
+#fi
+
+video_devices=()
+audio_devices=()
+
+tab=$(printf '\t')
+current_name=
+while IFS= read line; do
+    if ! [[ $line == "$tab"* ]]; then
+        current_name="$line"
+    else
+        video_devices+=("$(echo "$line - $current_name" | xargs)")
+    fi
+done < <( v4l2-ctl --list-devices )
+
+printf "%s\n" "${video_devices[@]}"
+
+current_name=
+current_device=
+current_subdevice=
+while IFS= read line; do
+    if ! [[ $line == "  "* ]]; then
+        current_name=$(echo $line | cut -d: -f2- | cut -c2-)
+        current_device=$(echo $line | grep -E 'card [0-9]+:' -o | tr -dc '[:digit:]' || true)
+    elif [[ $line == "  Subdevice #"* ]]; then
+        current_subdevice=$(echo $line | grep -E 'Subdevice #[0-9]+:' -o | tr -dc '[:digit:]' || true)
+        #audio_devices+=("$(echo "$line - $current_name" | xargs)")
+        audio_devices+=("hw:$current_device,$current_subdevice - $current_name")
+    else
+        :
+    fi
+done < <( arecord -l )
+
+
+printf "%s\n" "${audio_devices[@]}"
+
+
+zenity_cells=()
+maybe_true=TRUE
+for video_device in "${video_devices[@]}"; do
+    if grep <<<"$video_device" -q Elgato; then
+        zenity_cells+=("$maybe_true")
+        maybe_true=FALSE
+    else
+        zenity_cells+=(FALSE)
+    fi
+    zenity_cells+=("$video_device")
+done
+selected_video_device=$(
+    zenity --list --text="Which video device" --radiolist --column=Select --column=Device "${zenity_cells[@]}" \
+        | cut -d' ' -f1
+)
+
+zenity_cells=()
+maybe_true=TRUE
+for audio_device in "${audio_devices[@]}"; do
+    if grep <<<"$audio_device" -q Elgato; then
+        zenity_cells+=("$maybe_true")
+        maybe_true=FALSE
+    else
+        zenity_cells+=(FALSE)
+    fi
+    zenity_cells+=("$audio_device")
+done
+selected_audio_device=$(
+    zenity --list --text="Which audio device" --radiolist --column=Select --column=Device "${zenity_cells[@]}" \
+        | cut -d' ' -f1
+)
+
+ffmpeg_common=(
+    -fflags nobuffer
+    -flags low_delay
+)
+ffmpeg_args=(
+    -f v4l2
+        -input_format nv12
+        -video_size 1920x1080
+        -framerate 60
+        #-i /dev/video3
+        -i "$selected_video_device"
+    -f alsa
+        #-i hw:5,0
+        -i "$selected_audio_device"
+)
+
+set -x
+ffmpeg "${ffmpeg_common[@]}" "${ffmpeg_args[@]}" -c copy -f nut pipe: | ffplay "${ffmpeg_common[@]}" -f nut -i pipe: