feat(camera): several cameras in the picture, with layout sections

THIRD-PARTY-NOTICES.md

@@ -6,7 +6,9 @@ application resources and satisfies the attribution and source-offer obligations
 that come with them.
 
 npm dependencies are not listed here: they are resolved from `package.json` and
-distributed by their own registries, not redistributed inside our binaries.
+distributed by their own registries, not redistributed inside our binaries. The
+exception is code bundled into the renderer whose licence asks for its notice in
+the distributed form (js-aruco2 below): the bundler strips the source headers.
 
 ---
 
@@ -172,6 +174,49 @@ distributed by their own registries, not redistributed inside our binaries.
   notice as OpenScreen's own [LICENSE](LICENSE). Published by Recordly under MIT,
   before its relicensing in March 2026.
 
+## js-aruco2 — ArUco marker detection
+
+- **Components**: `src/aruco.js` and `src/cv.js` of the npm package `js-aruco2`
+  2.0.0, compiled into the renderer bundle (`dist/assets/*.js`).
+- **Used by**: the camera calibration dialog, which finds the four printed corner
+  markers in a camera still.
+- **License**: MIT — Copyright (c) 2020 Damiano Falcioni, Copyright (c) 2011 Juan
+  Mellado, under the same permission notice as OpenScreen's own
+  [LICENSE](LICENSE).
+- **Upstream**: <https://github.com/damianofalcioni/js-aruco2>, release 2.0.0.
+
+## OpenCV — ArUco 4×4 dictionary codes
+
+- **Component**: the marker codes in js-aruco2's
+  `src/dictionaries/aruco_4x4_1000.js`, compiled into the renderer bundle. They
+  are taken from OpenCV's `predefined_dictionaries.hpp`; the marker sheet the
+  editor prints draws markers 0–3 of this dictionary.
+- **License**: BSD 3-Clause — Copyright (C) 2013, OpenCV Foundation, all rights
+  reserved. Third party copyrights are property of their respective owners.
+
+  > Redistribution and use in source and binary forms, with or without
+  > modification, are permitted provided that the following conditions are met:
+  >
+  > - Redistributions of source code must retain the above copyright notice,
+  >   this list of conditions and the following disclaimer.
+  > - Redistributions in binary form must reproduce the above copyright notice,
+  >   this list of conditions and the following disclaimer in the documentation
+  >   and/or other materials provided with the distribution.
+  > - Neither the names of the copyright holders nor the names of the
+  >   contributors may be used to endorse or promote products derived from this
+  >   software without specific prior written permission.
+  >
+  > This software is provided by the copyright holders and contributors "as is"
+  > and any express or implied warranties, including, but not limited to, the
+  > implied warranties of merchantability and fitness for a particular purpose
+  > are disclaimed. In no event shall copyright holders or contributors be liable
+  > for any direct, indirect, incidental, special, exemplary, or consequential
+  > damages (including, but not limited to, procurement of substitute goods or
+  > services; loss of use, data, or profits; or business interruption) however
+  > caused and on any theory of liability, whether in contract, strict liability,
+  > or tort (including negligence or otherwise) arising in any way out of the use
+  > of this software, even if advised of the possibility of such damage.
+
 ## Rust crates — compiled into the compositor addon
 
 - **Component**: `compositor_view.node`, under

crates/compositor-view-napi/src/lib.rs

@@ -15,7 +15,7 @@ use openscreen_compositor::frame_geometry::FootageQuad;
 use openscreen_compositor::gif_export::{GifExportParams, GifStats};
 use openscreen_compositor::gif_export_control::{GifExportCancelled, GifExportControl};
 use openscreen_compositor::live::{LiveView, PausedPreviews};
-use openscreen_compositor::scene::Scene;
+use openscreen_compositor::scene::{Scene, SceneClipCamera};
 use openscreen_compositor::{config, pipeline};
 use std::collections::HashMap;
 use std::path::PathBuf;
@@ -368,6 +368,9 @@ pub fn present_time(id: i32, seconds: f64) {
 /// Remplace les sources du clip actif sans recréer la vue ni son thread de rendu. L'identité
 /// timeline et le playhead source sont atomiques avec le switch : deux clips partageant les
 /// mêmes fichiers restent distincts, et les deux décodeurs ouvrent directement la bonne frame.
+///
+/// `additional_cameras`: cameras 2-4 of the clip (index k-1 = camera k, an empty `path` = no
+/// camera in that slot). Absent = none; the view decodes only those its layout regions show.
 #[napi]
 pub fn set_active_clip(
     id: i32,
@@ -376,18 +379,33 @@ pub fn set_active_clip(
     webcam_offset_sec: f64,
     clip_index: u32,
     source_time_sec: f64,
+    additional_cameras: Option<Vec<ClipCameraInput>>,
 ) {
     if let Some(v) = registry().lock().unwrap().get(&id) {
+        let cameras = additional_cameras
+            .unwrap_or_default()
+            .into_iter()
+            .map(|c| SceneClipCamera { path: c.path, offset_sec: c.offset_sec })
+            .collect();
         v.set_active_clip(
             &screen_path,
             &webcam_path,
             webcam_offset_sec,
+            cameras,
             clip_index as usize,
             source_time_sec,
         );
     }
 }
 
+/// An additional camera of a clip (= TS `CompositorClipCamera`).
+#[napi(object)]
+pub struct ClipCameraInput {
+    pub path: String,
+    /// Camera source time = screen source time - this.
+    pub offset_sec: f64,
+}
+
 /// Installe la scène de l'app (JSON `SceneDescription`) sur la vue : layout preset piloté par
 /// l'app au lieu de la fixture. JSON invalide → ignoré côté natif.
 #[napi]
@@ -504,6 +522,26 @@ pub struct ClipInput {
     pub webcam_offset_sec: f64,
     /// `false` évite une ouverture ffmpeg vouée à échouer et réserve du silence à ce clip.
     pub has_audio: bool,
+    /// Cameras 2-4 of the clip (index k-1 = camera k, an empty `path` = none). Absent = none.
+    pub additional_cameras: Option<Vec<ClipCameraInput>>,
+}
+
+/// `ClipInput` → `pipeline::ClipSource`, shared by the MP4 and the GIF export.
+fn clip_source(c: ClipInput) -> pipeline::ClipSource {
+    pipeline::ClipSource {
+        screen: c.screen_path,
+        webcam: c.webcam_path,
+        source_start_sec: c.source_start_sec,
+        source_end_sec: c.source_end_sec,
+        webcam_offset_sec: c.webcam_offset_sec,
+        has_audio: c.has_audio,
+        additional_cameras: c
+            .additional_cameras
+            .unwrap_or_default()
+            .into_iter()
+            .map(|cam| pipeline::ClipCamera { path: cam.path, offset_sec: cam.offset_sec })
+            .collect(),
+    }
 }
 
 /// The export's pixel size. The SHAPE belongs to the scene: `scene.output` is what the live
@@ -701,17 +739,7 @@ pub fn export_multi(
     params: Option<ExportParamsInput>,
     on_progress: Option<JsFunction>,
 ) -> Result<AsyncTask<ExportMultiTask>> {
-    let clips = clips
-        .into_iter()
-        .map(|c| pipeline::ClipSource {
-            screen: c.screen_path,
-            webcam: c.webcam_path,
-            source_start_sec: c.source_start_sec,
-            source_end_sec: c.source_end_sec,
-            webcam_offset_sec: c.webcam_offset_sec,
-            has_audio: c.has_audio,
-        })
-        .collect();
+    let clips = clips.into_iter().map(clip_source).collect();
     Ok(AsyncTask::new(ExportMultiTask {
         out_path,
         clips,
@@ -882,17 +910,7 @@ pub fn export_gif(
     // Deliberately the same argument shape as `export_multi`: the caller builds
     // one clip list and one scene, and picks the container. Cursor comes from
     // the scene like every other effect — there is no GIF-specific input left.
-    let clips = clips
-        .into_iter()
-        .map(|c| pipeline::ClipSource {
-            screen: c.screen_path,
-            webcam: c.webcam_path,
-            source_start_sec: c.source_start_sec,
-            source_end_sec: c.source_end_sec,
-            webcam_offset_sec: c.webcam_offset_sec,
-            has_audio: c.has_audio,
-        })
-        .collect();
+    let clips = clips.into_iter().map(clip_source).collect();
     let gif_params = params
         .map(|p| GifExportParams {
             width: p.width,