Rework the "Extending org-mode to handle YouTube links" section

README.org

@@ -2956,61 +2956,50 @@ See `org-link-parameters' for details about PATH, DESC and FORMAT."
 :END:
 
 Listing [[lst:define-org-yt-link-type][define org-yt-link type]] implements code to open the link to the
-following YouTube video [[yt:eaZUZCzaIgw][Extending org-mode to handle YouTube links]] and the
-following [[https://raw.githubusercontent.com/bitspook/spookmax.d/master/readme.org][Emacs setup]].
+following YouTube video [[yt:eaZUZCzaIgw][Extending org-mode to handle YouTube links]] using the
+following [[https://raw.githubusercontent.com/bitspook/spookmax.d/master/readme.org][Emacs setup]].  Note: Listing [[lst:define-org-yt-link-type][define org-yt-link type]] does only
+implement normal links, but no embedded frames.
 
 Opening [[yt:eaZUZCzaIgw][Extending org-mode to handle YouTube links]] may fail due to a bug in the
 interface between =mpv= and =yt-dlp=.  Listing [[lst:set-emms-options][set EMMS options]] indicates how to
 work around this bug at the cost of making the user interface less clean.
 However, the link [[yt:48JlgiBpw_I][Absolute Beginner's Guide to Emacs]] works always.
 
-The following posts provide programming information:
-1. [[https://developers.google.com/youtube/v3/docs][YouTube API reference]].
-2. [[https://developers.google.com/youtube/iframe_api_reference][YouTube Player API reference for iframe embeds]].
-
 #+caption[Define an =org-link= type for =YouTube=]:
 #+caption: Define an =org-link= type for =YouTube=.
 #+name: lst:define-org-yt-link-type
 #+begin_src emacs-lisp -n :results silent
-;; https://bitspook.in/blog/extending-org-mode-to-handle-youtube-paths/
-(declare-function emms-add-url "emms-source-file" (url))
-(declare-function emms-playlist-last "emms" ())
-(declare-function emms-playlist-mode-play-current-track "emms-playlist-mode" ())
-(declare-function with-current-emms-playlist "emms" (&rest body))
+(when (ensure-package-installation 'emms)
+  ;; https://bitspook.in/blog/extending-org-mode-to-handle-youtube-paths/
+  (defun org-yt-emms-open (path)
+    "Open an \"YouTube\" PATH link with `emms' using \"mpv\"."
+    (let ((link (format "https://www.youtube.com/watch?v=%s" path)))
+      (require 'emms nil 'noerror)
+      (emms-add-url link)
+      (with-current-emms-playlist
+        (save-excursion
+          (emms-playlist-last)
+          (emms-playlist-mode-play-current-track)))))
 
-(defun org-yt-emms-open (path)
-  "Open an \"YouTube\" PATH link with `emms' using \"mpv\"."
-  (let ((url (format "https://www.youtube.com/watch?v=%s" path)))
-    (require 'emms nil 'noerror)
-    (emms-add-url url)
-    (with-current-emms-playlist
-      (save-excursion
-        (emms-playlist-last)
-        (emms-playlist-mode-play-current-track)))))
+  (defun org-yt-url-browse-open (path)
+    "Open an \"YouTube\" PATH link with `url-browse'."
+    (let ((link (format "https://www.youtube.com/watch?v=%s" path)))
+      (browse-url link)))
 
-(defun org-yt-url-browse-open (path)
-  "Open an \"YouTube\" PATH link with `url-browse'."
-  (let ((url (format "https://www.youtube.com/watch?v=%s" path)))
-    (browse-url url)))
+  (defun org-yt-export (path desc backend _)
+    "Export an \"YouTube\" PATH link according to DESC and BACKEND."
+    (pcase backend
+      (`ascii
+       (format "[%s] <https://www.youtube.com/watch?v=%s>" desc path))
+      (`html
+       (format "<a href=\"https://www.youtube.com/watch?v=%s\">%s</a>" path desc))
+      (`latex
+       (format "\\href{https://www.youtube.com/watch?v=%s}{%s}" path desc))
+      (_ path)))
 
-(defun org-yt-export (path desc backend _)
-  "Export an \"YouTube\" PATH link according to DESC and BACKEND."
-  (pcase backend
-    (`ascii
-     (format "[%s] <https://www.youtube.com/watch?v=%s>" desc path))
-    (`html
-     (format "<iframe
-  frameborder=\"0\" width=\"600\" height=\"450\"
-  src=\"https://www.youtube.com/embed/%s\"
-  title=\"%s\"
-  allowfullscreen></iframe>" path desc))
-    (`latex
-     (format "\\href{https://www.youtube.com/watch?v=%s}{%s}" path desc))
-    (_ path)))
-
-(with-eval-after-load 'ol
-  (org-link-set-parameters
-   "yt" :follow #'org-yt-emms-open :export #'org-yt-export))
+  (with-eval-after-load 'ol
+    (org-link-set-parameters
+     "yt" :follow #'org-yt-emms-open :export #'org-yt-export)))
 #+end_src
 
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