Brought-in footage plays at the project's rate

The new symbol gets project-rate frames covering the same wall-clock length,
and its root and sound map them back onto the source's frames.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/arthur/domain/bring.cljs

@@ -71,6 +71,21 @@
   [clip frozen label footage-id range]
   (let [{c :clip ids :ids} (symbols clip frozen [:main] {:main (symbol-id label)})
         sid      (ids :main)
+        source-fps (:fps frozen)
+        project-fps (:fps clip)
+        ;; The new symbol is played by the receiving project's clock. Keep its
+        ;; wall-clock duration by giving it project-rate frames, while its root
+        ;; maps those frames back onto the source timeline. A 30fps source in a
+        ;; 12fps project therefore has 2.5 source frames per project frame.
+        source-rate (if (and (number? source-fps) (pos? source-fps)
+                            (number? project-fps) (pos? project-fps))
+                      (/ source-fps project-fps)
+                      1)
+        output-frames (max 1 (js/Math.ceil (/ (clip/frames c sid) source-rate)))
+        c (-> c
+              (assoc-in [:symbols sid :frames] output-frames)
+              (update-in [:symbols sid :nodes :root :time]
+                         #(assoc (or % {}) :mode :map :at 0 :rate source-rate)))
         tracked? (and (nil? (:analysis clip))
                       (every? #(= % (ids %)) (keys (:subjects frozen))))]
     {:sid sid
@@ -81,7 +96,10 @@
                                  {:id :sound :name "sound" :kind :audio :parent nil
                                   :z "z-sound" :source {:footage footage-id}
                                   ;; Source frame `start` plays on the symbol's 0.
-                                  :span range :time {:mode :map :at (- (first range)) :rate 1}}))
+                                  :span range
+                                  :time {:mode :map
+                                         :at (/ (- (first range)) source-rate)
+                                         :rate source-rate}}))
              tracked? (-> (assoc :analysis (:analysis frozen))
                           (update :subjects merge (:subjects frozen))
                           (update :features merge (:features frozen))

frontend/src/arthur/events/footage.cljs

@@ -5,6 +5,7 @@
   detector's identity comes from the server too, because it goes into the content
   address of every block this produces."
   (:require [arthur.domain.bring :as bring]
+            [arthur.domain.clip :as clip]
             [arthur.events.edit :as edit]
             [arthur.events.playback :as pb]
             [arthur.flow.detect :as detect]
@@ -432,6 +433,8 @@
          {:keys [clip sid tracked?]}
          (bring/take (:clip (store/entry (:clip/current db))) (:clip built)
                      name footage-id range)
+         imported-frames (clip/frames clip sid)
+         source-fps (get-in built [:clip :fps])
          db    (edit/edit-entry
                 db
                 #(cond-> (bring/placed % clip (:store built) sid host frame uuid point)
@@ -442,10 +445,9 @@
               (assoc-in [:ui :selection] [:node host uuid [uuid]])
               (update :footage merge
                       {:loading? false
-                       :status (str "made " name " · " (- (second range) (first range)) " frames"
+                       :status (str "made " name " · " imported-frames " frames at " fps " fps"
+                                    (when (not= fps source-fps)
+                                      (str " · sampled from " source-fps " fps"))
                                     (when-not tracked?
-                                      " · as drawings: this project already tracks other footage")
+                                      " · as drawings: this project already tracks other footage"))}))
-                                    (when (not= fps (get-in built [:clip :fps]))
-                                      (str " · footage is " (get-in built [:clip :fps])
-                                           " fps, this project " fps)))}))
       :dispatch [::pb/refresh-clock]})))