Docs

animation.wiki

@@ -3,20 +3,24 @@
 Utility for creating animations from a series of images
 [[toc:]]
 === {{make-animator}}
-<procedure>(make-animator #!key (magnitude 10000) (frames-per-second 4) (type png)) → Two values: next-frame and finalize</procedure>
+<procedure>(make-animator #!key (magnitude 10000) (frames-per-second 4) (type png) (width 1600) (height 900)) → Two values: next-frame and finalize</procedure>
 Create an animator, which consists of two values: a frame-creator and a finalizer.
 
 {{Next-frame}} is a niladic function which returns the filename
 of the next frame; {{finalize}} is a monadic function taking the
-basename of the animation (e.g. {{graph}} → {{graph.avi}}).
+name of the resultant animation (e.g. {{graph.avi}}).
 ; magnitude : Roughly the number of animations one anticipates
 ; frames-per-second : Frames per second
 ; type : The frame type; one of e.g. "png", "jpg"
+; width : The width of the frame in pixels (#f for no scaling)
+; height : The height of the frame (#f for no scaling)
 <enscript highlight="scheme">(define (make-animator
          #!key
          (magnitude 10000)
          (frames-per-second 4)
-         (type "png"))
+         (type "png")
+         (width 1600)
+         (height 900))
   (let ((directory (create-temporary-directory))
         (current-frame 0)
         (digits (inexact->exact (ceiling (/ (log magnitude) (log 10))))))
@@ -28,20 +32,22 @@ basename of the animation (e.g. {{graph}} → {{graph.avi}}).
         (inc! current-frame)
         frame))
     (define (finalize animation)
-      (run (cd ,directory
-               &&
-               mencoder
+      (let ((options
+              (option-string
+                (append
+                  `((type unquote type) (fps unquote frames-per-second))
+                  (if width `((w unquote width)) '())
+                  (if height `((h unquote height)) '())))))
+        (run (mencoder
                ,(format
                   "mf://~a"
                   (make-pathname directory (format "*.~a" type)))
                -mf
-               ,(format "type=~a:fps=~a" type frames-per-second)
+               ,options
                -ovc
                lavc
                -o
-               ,(if (absolute-pathname? animation)
-                  animation
-                  (make-pathname (current-directory) animation ".avi")))))
+               ,animation))))
     (values next-frame finalize)))
 </enscript>
 ==== Examples