Change volume of playback ports by default

This seems to be more correct than changing volume of the whole sink.
The default volume of the sink is 1 (100) and alsamixer also changes
volume of the ports.

pw-lib.el

@@ -30,10 +30,12 @@
 (defvar pw-lib--accessor (pw-cli-accessor))
 
 (defvar pw-lib--objects '())
+(defvar pw-lib--bindings nil)
 
 (defun pw-lib-refresh ()
   "Clear cache of objects retrieved from PipeWire."
-  (setq pw-lib--objects (pw-access-objects pw-lib--accessor)))
+  (setq pw-lib--objects (pw-access-objects pw-lib--accessor)
+        pw-lib--bindings nil))
 
 (defun pw-lib-objects (&optional type)
   "Return a list of PipeWire objects.
@@ -119,23 +121,26 @@ An association lists with elements of the form (PARENT . CHILD) is
 returned where PARENT and CHILD are numeric ids of PipeWire objects.
 Note that PipeWire data is cached, if you need its up-to-date
 version, call `pw-lib-refresh' first."
-  (apply #'nconc (mapcar #'(lambda (o)
+  (or pw-lib--bindings
+      (setq pw-lib--bindings
+            (apply #'nconc
+                   (mapcar #'(lambda (o)
                                (let ((o-id (pw-lib-object-id o)))
                                  (mapcar #'(lambda (p)
                                              (cons o-id (cdr p)))
                                          (cl-remove-if-not #'numberp (pw-lib--object-info o)
                                                            :key #'cdr))))
-                         (pw-lib-objects))))
+                           (pw-lib-objects))))))
 
-(defun pw-lib-children (id bindings &optional type)
+(defun pw-lib-children (id &optional type)
   "Return child objects of the object identified by numeric PipeWire ID.
-BINDINGS are object bindings as returned from `pw-lib-bindings'.
 If a string TYPE is specified then only children of the given PipeWire
 type are returned.
 Note that PipeWire data is cached, if you need its up-to-date
 version, call `pw-lib-refresh' first."
   (let ((children (mapcar #'pw-lib-get-object
-                          (mapcar #'car (cl-remove-if #'(lambda (b) (/= (cdr b) id)) bindings)))))
+                          (mapcar #'car (cl-remove-if #'(lambda (b) (/= (cdr b) id))
+                                                      (pw-lib-bindings))))))
     (when type
       (setq children (cl-remove-if-not #'(lambda (o) (equal (pw-lib-object-type o) type))
                                        children)))
@@ -145,6 +150,13 @@ version, call `pw-lib-refresh' first."
   "Return a PipeWire object that is the current default audio sink."
   (pw-lib-get-object (cdr (assoc "default.audio.sink" (pw-lib-default-nodes)))))
 
+(defun pw-lib-default-playback-ports ()
+  "Return list of PipeWire objects that are default playback ports."
+  (cl-remove-if-not #'(lambda (o)
+                        (if-let ((name (pw-lib-object-value o "port.name")))
+                            (string-match "^playback" name)))
+                    (pw-lib-children (pw-lib-object-id (pw-lib-default-audio-sink)) "Port")))
+
 (defun pw-lib--volume-% (volume)
   (when volume
     (round (* 100 volume))))
@@ -233,7 +245,7 @@ If STORED-P is non-nil, set the stored default sink or source,
 otherwise set the current default sink or source."
   (pcase (pw-lib-object-type object)
     ("Device"
-     (dolist (node (pw-lib-children (pw-lib-object-id object) (pw-lib-bindings) "Node"))
+     (dolist (node (pw-lib-children (pw-lib-object-id object) "Node"))
        (pw-lib--set-default-node node stored-p)))
     ("Node"
      (pw-lib--set-default-node object stored-p))

pw-ui.el

@@ -137,16 +137,15 @@ The indicator is displayed only on graphical terminals."
     (error "Not in a PipeWire buffer"))
   (pw-lib-refresh)
   (let ((inhibit-read-only t)
-        (bindings (pw-lib-bindings))
         (default-ids (mapcar #'cdr (pw-lib-default-nodes)))
         (current-line (count-lines (point-min) (min (1+ (point)) (point-max)))))
     (erase-buffer)
     (insert (pw-ui--label "Devices") "\n")
     (dolist (device (pw-lib-objects "Device"))
       (pw-ui--insert-line (pw-ui--object-label device default-ids) device)
-      (dolist (node (pw-lib-children (pw-lib-object-id device) bindings "Node"))
+      (dolist (node (pw-lib-children (pw-lib-object-id device) "Node"))
         (pw-ui--insert-line (concat "  " (pw-ui--object-label node default-ids)) node)
-        (dolist (port (pw-lib-children (pw-lib-object-id node) bindings "Port"))
+        (dolist (port (pw-lib-children (pw-lib-object-id node) "Port"))
           (pw-ui--insert-line (concat "    " (pw-ui--object-label port default-ids)) port))))
     (insert (pw-ui--label "Clients") "\n")
     (dolist (client (pw-lib-objects "Client"))
@@ -165,7 +164,8 @@ The indicator is displayed only on graphical terminals."
                (not (member (pw-lib-object-type object) allowed-types)))
       (setq object nil))
     (when (and use-default-p (not object))
-      (setq object (pw-lib-default-audio-sink)))
+      (setq object (or (car (pw-lib-default-playback-ports))
+                       (pw-lib-default-audio-sink))))
     object))
 
 (defvar pw-ui--osd-timer nil)