gnu: Add emacs-emms-player-simple-mpv.

* gnu/packages/emacs.scm (emacs-emms-player-simple-mpv): New public variable.

gnu/packages/emacs.scm

@@ -9414,3 +9414,30 @@ functions.")
     (description "@code{benchmark-init} provides a way to keep track of where
 time is being spent during Emacs startup in order to optimize startup time.")
     (license license:gpl3+)))
+
+(define-public emacs-emms-player-simple-mpv
+  (let ((commit "101d120ccdee1c2c213fd2f0423c858b21649c00")
+        (revision "1"))
+    (package
+      (name "emacs-emms-player-simple-mpv")
+      (version (string-append "0.4.0" "-" revision "."
+                              (string-take commit 7)))
+
+      (source
+       (origin
+         (method git-fetch)
+         (uri (git-reference
+               (url "https://github.com/momomo5717/emms-player-simple-mpv.git")
+               (commit commit)))
+         (file-name (git-file-name name version))
+         (sha256
+          (base32
+           "1i6rxkm0ra0jbkkwgkwxg3vk5xfl794h1gkgnlpscynz0v94b6ll"))))
+      (build-system emacs-build-system)
+      (propagated-inputs
+       `(("emacs-emms" ,emms)))
+      (home-page "https://github.com/momomo5717/emms-player-simple-mpv")
+      (synopsis "Extension of @file{emms-player-simple.el} for mpv JSON IPC")
+      (description "@code{emms-player-simple-mpv} provides macros and
+functions for defining emms simple players of mpv.")
+      (license license:gpl3+))))