add initial v4l2loopback support

README.md

@@ -30,15 +30,63 @@ flatpak install camera-x86_64.flatpak
 
 ### From Source
 
-#### Dependencies
+#### Build Dependencies
 
 - Rust (stable)
-- GStreamer 1.0 with plugins (base, good, bad, ugly)
-- libwayland
-- libxkbcommon
-- libinput
-- libudev
-- libseat
+- GStreamer 1.0 development libraries
+- libwayland-dev
+- libxkbcommon-dev
+- libinput-dev
+- libudev-dev
+- libseat-dev
+
+#### Runtime Dependencies
+
+| Dependency | Required | Purpose |
+|------------|----------|---------|
+| PipeWire | Yes | Camera access and audio |
+| GStreamer 1.0 | Yes | Video processing pipeline |
+| gst-plugins-base | Yes | Core GStreamer elements |
+| gst-plugins-good | Yes | Video encoding (x264, vpx) |
+| gst-plugins-bad | Yes | Additional encoders |
+| gst-plugin-pipewire | Yes | PipeWire integration |
+| GPU drivers | Recommended | Hardware-accelerated filters |
+| v4l2loopback | Optional | Virtual camera for Discord, Chrome, etc. |
+
+##### Fedora/RHEL
+
+```bash
+sudo dnf install pipewire gstreamer1 gstreamer1-plugins-base \
+    gstreamer1-plugins-good gstreamer1-plugins-bad-free \
+    pipewire-gstreamer mesa-dri-drivers
+
+# Optional: Virtual camera for Discord/Chrome
+sudo dnf install v4l2loopback
+sudo modprobe v4l2loopback devices=1 video_nr=10 card_label="Camera Virtual" exclusive_caps=1
+```
+
+##### Ubuntu/Debian
+
+```bash
+sudo apt install pipewire gstreamer1.0-tools gstreamer1.0-plugins-base \
+    gstreamer1.0-plugins-good gstreamer1.0-plugins-bad \
+    gstreamer1.0-pipewire mesa-utils
+
+# Optional: Virtual camera for Discord/Chrome
+sudo apt install v4l2loopback-dkms v4l2loopback-utils
+sudo modprobe v4l2loopback devices=1 video_nr=10 card_label="Camera Virtual" exclusive_caps=1
+```
+
+##### Arch Linux
+
+```bash
+sudo pacman -S pipewire gstreamer gst-plugins-base gst-plugins-good \
+    gst-plugins-bad gst-plugin-pipewire mesa
+
+# Optional: Virtual camera for Discord/Chrome
+sudo pacman -S v4l2loopback-dkms
+sudo modprobe v4l2loopback devices=1 video_nr=10 card_label="Camera Virtual" exclusive_caps=1
+```
 
 #### Build
 

i18n/en/camera.ftl

@@ -15,6 +15,10 @@ mode-virtual = VIRTUAL
 virtual-camera-title = Virtual camera (experimental)
 virtual-camera-description = Stream your camera feed to other applications via a virtual camera device. Requires PipeWire.
 virtual-camera-enable = Enable virtual camera
+virtual-camera-output = Output device
+virtual-camera-output-pipewire = PipeWire
+virtual-camera-output-v4l2loopback = V4L2 Loopback
+virtual-camera-output-unavailable = ({ $reason })
 streaming-live = LIVE
 virtual-camera-open-file = Open file
 virtual-camera-file-filter-name = Images and Videos

src/app/handlers/virtual_camera.rs

@@ -8,6 +8,7 @@
 use crate::app::state::{
     AppModel, FileSource, FilterType, Message, VideoPlaybackCommand, VirtualCameraState,
 };
+use cosmic::cosmic_config::CosmicConfigEntry;
 use cosmic::Task;
 use std::sync::Arc;
 use tracing::{debug, error, info, warn};
@@ -54,10 +55,12 @@ impl AppModel {
         let height = format.height;
         let filter_type = self.selected_filter;
 
+        let output_type = self.config.virtual_camera_output;
         info!(
             width,
             height,
             ?filter_type,
+            ?output_type,
             "Starting virtual camera streaming from camera"
         );
 
@@ -78,7 +81,7 @@ impl AppModel {
             use crate::backends::virtual_camera::VirtualCameraManager;
 
             // Create and start the virtual camera on this dedicated thread
-            let mut manager = VirtualCameraManager::new();
+            let mut manager = VirtualCameraManager::new(output_type);
             manager.set_filter(filter_type);
 
             let result = (|| {
@@ -170,11 +173,13 @@ impl AppModel {
         self.stop_video_preview_playback();
 
         let filter_type = self.selected_filter;
+        let output_type = self.config.virtual_camera_output;
         let is_video = matches!(file_source, FileSource::Video(_));
 
         info!(
             ?file_source,
             ?filter_type,
+            ?output_type,
             "Starting virtual camera from file source"
         );
 
@@ -226,13 +231,15 @@ impl AppModel {
                 FileSource::Image(path) => Self::stream_image_to_virtual_camera(
                     &path,
                     filter_type,
+                    output_type,
                     &mut filter_rx,
                     stop_rx,
                     preview_tx,
                 ),
                 FileSource::Video(path) => Self::stream_video_to_virtual_camera(
                     &path,
                     filter_type,
+                    output_type,
                     &mut filter_rx,
                     stop_rx,
                     preview_tx,
@@ -278,6 +285,7 @@ impl AppModel {
     fn stream_image_to_virtual_camera(
         path: &std::path::Path,
         initial_filter: FilterType,
+        output_type: crate::constants::VirtualCameraOutput,
         filter_rx: &mut tokio::sync::watch::Receiver<FilterType>,
         mut stop_rx: tokio::sync::oneshot::Receiver<()>,
         preview_tx: tokio::sync::mpsc::UnboundedSender<
@@ -294,7 +302,7 @@ impl AppModel {
         let height = frame.height;
 
         // Create and start virtual camera manager
-        let mut manager = VirtualCameraManager::new();
+        let mut manager = VirtualCameraManager::new(output_type);
         manager.set_filter(initial_filter);
         // File sources should not be mirrored - output exactly as the file content
 
@@ -358,6 +366,7 @@ impl AppModel {
     fn stream_video_to_virtual_camera(
         path: &std::path::Path,
         initial_filter: FilterType,
+        output_type: crate::constants::VirtualCameraOutput,
         filter_rx: &mut tokio::sync::watch::Receiver<FilterType>,
         mut stop_rx: tokio::sync::oneshot::Receiver<()>,
         preview_tx: tokio::sync::mpsc::UnboundedSender<
@@ -383,7 +392,7 @@ impl AppModel {
         let (width, height) = decoder.dimensions();
 
         // Create and start virtual camera manager
-        let mut manager = VirtualCameraManager::new();
+        let mut manager = VirtualCameraManager::new(output_type);
         manager.set_filter(initial_filter);
         // File sources should not be mirrored - output exactly as the file content
 
@@ -558,6 +567,46 @@ impl AppModel {
         )
     }
 
+    pub(crate) fn handle_select_virtual_camera_output(
+        &mut self,
+        index: usize,
+    ) -> Task<cosmic::Action<Message>> {
+        use crate::constants::VirtualCameraOutput;
+
+        let Some(output_type) = VirtualCameraOutput::ALL.get(index).copied() else {
+            warn!(index, "Invalid virtual camera output index");
+            return Task::none();
+        };
+
+        // Check if the selected output is available
+        if !output_type.is_available() {
+            warn!(
+                ?output_type,
+                reason = ?output_type.unavailable_reason(),
+                "Selected virtual camera output is not available"
+            );
+            // Don't change the selection if it's not available
+            return Task::none();
+        }
+
+        // Don't change if already selected
+        if self.config.virtual_camera_output == output_type {
+            return Task::none();
+        }
+
+        info!(?output_type, "Virtual camera output changed");
+        self.config.virtual_camera_output = output_type;
+
+        // Save the config change
+        if let Some(handler) = self.config_handler.as_ref() {
+            if let Err(err) = self.config.write_entry(handler) {
+                error!(?err, "Failed to save virtual camera output setting");
+            }
+        }
+
+        Task::none()
+    }
+
     pub(crate) fn handle_virtual_camera_stopped(
         &mut self,
         result: Result<(), String>,

src/app/mod.rs

@@ -295,7 +295,18 @@ impl cosmic::Application for AppModel {
                 .map(|p| p.display_name().to_string())
                 .collect(),
             theme_dropdown_options: vec![fl!("match-desktop"), fl!("dark"), fl!("light")],
+            virtual_camera_output_dropdown_options: crate::constants::VirtualCameraOutput::ALL
+                .iter()
+                .map(|o| {
+                    if o.is_available() {
+                        o.display_name().to_string()
+                    } else {
+                        format!("{} (unavailable)", o.display_name())
+                    }
+                })
+                .collect(),
             device_info_visible: false,
+            bitrate_info_visible: false,
             transition_state: crate::app::state::TransitionState::default(),
             // QR detection enabled by default
             qr_detection_enabled: true,

src/app/settings/view.rs

@@ -126,13 +126,29 @@ impl AppModel {
         );
 
         // Virtual camera section
-        let virtual_camera_section = widget::settings::section().add(
-            widget::settings::item::builder(fl!("virtual-camera-title"))
-                .description(fl!("virtual-camera-description"))
-                .toggler(self.config.virtual_camera_enabled, |_| {
-                    Message::ToggleVirtualCameraEnabled
-                }),
-        );
+        // Get current output index for dropdown
+        let current_output_index = crate::constants::VirtualCameraOutput::ALL
+            .iter()
+            .position(|o| *o == self.config.virtual_camera_output)
+            .unwrap_or(0);
+
+        let virtual_camera_section = widget::settings::section()
+            .add(
+                widget::settings::item::builder(fl!("virtual-camera-title"))
+                    .description(fl!("virtual-camera-description"))
+                    .toggler(self.config.virtual_camera_enabled, |_| {
+                        Message::ToggleVirtualCameraEnabled
+                    }),
+            )
+            .add(
+                widget::settings::item::builder(fl!("virtual-camera-output")).control(
+                    widget::dropdown(
+                        &self.virtual_camera_output_dropdown_options,
+                        Some(current_output_index),
+                        Message::SelectVirtualCameraOutput,
+                    ),
+                ),
+            );
 
         // Bug reports section
         let bug_report_button = widget::button::standard(fl!("settings-report-bug"))

src/app/state.rs

@@ -402,8 +402,12 @@ pub struct AppModel {
     pub bitrate_preset_dropdown_options: Vec<String>,
     /// Theme dropdown options (Match Desktop, Dark, Light)
     pub theme_dropdown_options: Vec<String>,
+    /// Virtual camera output dropdown options (with availability indicators)
+    pub virtual_camera_output_dropdown_options: Vec<String>,
     /// Whether the device info panel is visible
     pub device_info_visible: bool,
+    /// Whether the bitrate info matrix is visible
+    pub bitrate_info_visible: bool,
 
     /// Transition state for camera/settings changes
     pub transition_state: TransitionState,
@@ -908,6 +912,8 @@ pub enum Message {
     SelectVideoEncoder(usize),
     /// Toggle virtual camera feature enabled
     ToggleVirtualCameraEnabled,
+    /// Select virtual camera output device type
+    SelectVirtualCameraOutput(usize),
 
     // ===== System & Recovery =====
     /// Camera backend recovery started

src/app/update.rs

@@ -109,6 +109,9 @@ impl AppModel {
             Message::ClearTransitionBlur => self.handle_clear_transition_blur(),
             Message::ToggleMirrorPreview => self.handle_toggle_mirror_preview(),
             Message::ToggleVirtualCameraEnabled => self.handle_toggle_virtual_camera_enabled(),
+            Message::SelectVirtualCameraOutput(index) => {
+                self.handle_select_virtual_camera_output(index)
+            }
 
             // ===== Format Selection =====
             Message::SetMode(mode) => self.handle_set_mode(mode),

src/backends/virtual_camera/mod.rs

@@ -40,6 +40,7 @@ pub use pipeline::VirtualCameraPipeline;
 
 use crate::app::FilterType;
 use crate::backends::camera::types::{BackendError, BackendResult, CameraFrame};
+use crate::constants::VirtualCameraOutput;
 use std::sync::Arc;
 use tokio::sync::Mutex;
 use tracing::{debug, error, info, warn};
@@ -66,18 +67,21 @@ pub struct VirtualCameraManager {
     gpu_available: bool,
     /// Whether to horizontally flip output (for file sources, to counteract app auto-mirroring)
     flip_horizontal: bool,
+    /// Output type (PipeWire or V4L2Loopback)
+    output_type: VirtualCameraOutput,
 }
 
 impl VirtualCameraManager {
-    /// Create a new virtual camera manager
-    pub fn new() -> Self {
+    /// Create a new virtual camera manager with the specified output type
+    pub fn new(output_type: VirtualCameraOutput) -> Self {
         Self {
             pipeline: None,
             current_filter: FilterType::Standard,
             streaming: false,
             output_size: (1280, 720),
             gpu_available: false,
             flip_horizontal: false,
+            output_type,
         }
     }
 
@@ -92,7 +96,10 @@ impl VirtualCameraManager {
 
     /// Start streaming to virtual camera
     ///
-    /// Creates a PipeWire virtual camera node that will be visible to other applications.
+    /// Creates a virtual camera output that will be visible to other applications:
+    /// - PipeWire: Creates a PipeWire virtual camera node
+    /// - V4L2Loopback: Writes to a /dev/video* loopback device
+    ///
     /// Uses GPU-accelerated filtering with software rendering fallback.
     pub fn start(&mut self, width: u32, height: u32) -> BackendResult<()> {
         if self.streaming {
@@ -101,10 +108,10 @@ impl VirtualCameraManager {
             ));
         }
 
-        info!(width, height, "Starting virtual camera");
+        info!(width, height, ?self.output_type, "Starting virtual camera");
 
-        // Create and start the pipeline
-        let pipeline = VirtualCameraPipeline::new(width, height)?;
+        // Create and start the pipeline with the configured output type
+        let pipeline = VirtualCameraPipeline::new(width, height, self.output_type)?;
         pipeline.start()?;
 
         self.pipeline = Some(pipeline);
@@ -310,7 +317,7 @@ impl VirtualCameraManager {
 
 impl Default for VirtualCameraManager {
     fn default() -> Self {
-        Self::new()
+        Self::new(VirtualCameraOutput::default())
     }
 }