refactor: eliminate magic numbers by introducing named constants

src/const.lisp

@@ -33,3 +33,9 @@
 
 (defparameter +gif-scale+ "640:-1")
 
+(defparameter +gif-fps-divider+ 2.0
+  "Divider for GIF frame rate (output fps = source fps / divider)")
+
+(defparameter +min-file-size+ 4096
+  "Minimum file size in bytes to consider a file valid (not corrupt/incomplete)")
+

src/ffmpeg.lisp

@@ -24,7 +24,7 @@
                                              :if-does-not-exist nil)
                        (when stream (file-length stream)))))
       ;; Delete empty or very small files (header-only, etc.)
-      (when (and file-size (< file-size 1024))
+      (when (and file-size (< file-size +min-file-size+))
         (delete-file output)
         (format t "~a Cleaned up incomplete output file: ~a~%" 
                 (log-tag "info") output)))))
@@ -55,7 +55,7 @@
   "Construct the ffmpeg command list for GIF mode using input filename and target fps."
   (let* ((input (visp-options-input opts))
          (cmd (list "ffmpeg" "-i" input))
-         (half-fps (/ fps 2.0))
+         (half-fps (/ fps +gif-fps-divider+))
          (scale-str (format nil "scale=~a" +gif-scale+))
          (fps-str (format nil "fps=~2,2f" half-fps))
          (filter-complex

src/package.lisp

@@ -9,6 +9,8 @@
    :+pixfmt-name-map+
    :+allowed-input-extensions+
    +gif-scale+
+   +gif-fps-divider+
+   +min-file-size+
 
    ;; main.lisp
    :main