before trying to create elements separately

gstreamer/tutorial-hello-world.lisp

@@ -61,23 +61,16 @@
 ;; videotestsc worked
 ;; and error i got was from trying to set :null ? but it should be correct enum
 ;; oh well, ok
-(defun for-screencast ()
+(defun for-screencast (stream-num)
   (gir:invoke (*gstreamer* 'init) '())
-  (let ((pipeline (gir:invoke (*gstreamer* 'parse-launch)
+  (let* ((pipeline
-										"pipewiresrc path=46 ! videoconvert ! autovideosink"
+			 (gir:invoke (*gstreamer* 'parse-launch)
+							 (format nil "pipewiresrc path=~A ! videoconvert ! videobox name=move ! autovideosink" stream-num)
 													 ;"playbin uri=https://gstreamer.freedesktop.org/data/media/sintel_trailer-480p.webm"
-										)))
-	 (gir:invoke (pipeline 'set-state)
-					 (gir:nget *gstreamer* "State" :playing))
-	 ;; (let* ((bus (gir:invoke (pipeline 'get-bus)))
-	 ;; 		  (msg (gir:invoke (bus 'timed-pop-filtered)
-	 ;; 								 (gir:nget *gstreamer* :clock-time-none)
-	 ;; 								 (list
-	 ;; 								  (gir:nget *gstreamer* "MessageType" :error)
-	 ;; 								  (gir:nget *gstreamer* "MessageType" :eos))))))
-	 ;; (gir:invoke (pipeline 'set-state)
-	 ;; 				 (gir:nget *gstreamer* "State" :paused))
 							 ))
+			(move-element (gir:invoke (pipeline 'get-by-name) "move")))
+	 (gir:invoke (pipeline 'set-state) (gir:nget *gstreamer* "State" :playing))
+	 (values pipeline move-element)))
 
 ;; well, pipewire is not part of what's added to env
 ;; not sure if i can add it
@@ -87,3 +80,17 @@
 ;; i can try to add pipewire, but then would it work with the screen share running on system server?
 ;; it did work. wowy. ok
 ;; cool. now i'm kind of at the point of python example :D
+
+;; let's generalize, when stream is not passed, use the testsrc
+(defun moving-cast (&optional stream-num)
+  (gir:invoke (*gstreamer* 'init) '())
+  (let* ((source (if stream-num
+							(format nil "pipewiresrc path=~A" stream-num)
+							"videotestsrc"))
+			(pipeline
+			  (gir:invoke (*gstreamer* 'parse-launch)
+							  (format nil "~A ! videoconvert ! videobox name=move ! autovideosink" source))))
+													 ;	 (format t "~A" (gir:nget pipeline 'get-state))
+	 (gir:invoke (pipeline 'set-state) (gir:nget *gstreamer* "State" :playing))
+	 pipeline))
+

notes.org

@@ -210,3 +210,65 @@ so. tried removing all from shell env, then not found namespace Gst
 (defvar *gstreamer* (gir:require-namespace "Gst"))
 
 so. yeah. maybe i need to install dev headers or something?
+
+** so. for moving the video around. chatgpt recommended something named 'videobox'
+
+like i can declare it in the pipeline and then get reference to it and use to set video coordinates, huh?
+https://gstreamer.freedesktop.org/documentation/videobox/index.html?gi-language=python
+the thing exists but i have zero idea whether it's accessible in a way that's recommended
+#+begin_src lisp
+(defun for-screencast ()
+  (gir:invoke (*gstreamer* 'init) '())
+  (let* ((pipeline (gir:invoke (*gstreamer* 'parse-launch)
+                                "pipewiresrc path=49 ! videoconvert ! videobox top=0 left=0 right=0 bottom=0 ! videoconvert ! autovideosink"
+                                ))
+         (videobox (gir:invoke (pipeline 'get-element-by-name) "videobox")))
+    ;; Set the initial state to playing
+    (gir:invoke (pipeline 'set-state) (gir:nget *gstreamer* "State" :playing))
+    
+    ;; Function to move the video
+    (defun move-video (top left)
+      (gir:invoke (videobox 'set-property) 'top top)
+      (gir:invoke (videobox 'set-property) 'left left))
+
+    ;; Example: Move the video 10 pixels down and 20 pixels to the right
+    (move-video 10 20)))
+#+end_src
+
+and similar advice from claude, huh
+#+begin_src lisp
+(defun for-screencast ()
+  (gir:invoke (*gstreamer* 'init) '())
+  (let* ((pipeline (gir:invoke (*gstreamer* 'parse-launch)
+                               "pipewiresrc path=49 ! videoconvert ! videobox name=move ! videoscale ! autovideosink"))
+         (move-element (gir:invoke (pipeline 'get-by-name) "move")))
+    (gir:invoke (pipeline 'set-state) (gir:nget *gstreamer* "State" :playing))
+    (values pipeline move-element)))
+
+(defun move-video (move-element left top)
+  (gir:set-property move-element "left" left)
+  (gir:set-property move-element "top" top))
+
+;; Usage:
+(multiple-value-bind (pipeline move-element) (for-screencast)
+  ;; Move video 50 pixels to the right and 30 pixels down
+  (move-video move-element 50 30)
+  ;; Your main loop or other logic here
+  )
+#+end_src
+
+let's try this out
+
+* [2024-08-16 Fri]
+
+** new day of the vacation
+the experiment with moving the video, right?
+
+could it be that both examples are fake? i don't seem to find both 'get-element things
+
+trying to find anything about dynamism in gstreamer
+https://coaxion.net/blog/2014/01/gstreamer-dynamic-pipelines/
+looks like this is about changing elements of the pipeline
+
+and it's possible that parameters of the pipeline elements (pads?) are also static
+