elisp 怎么对像“17:15” 的时间字符串进行加减

Emacs-Lisp
1

elisp 怎么对像“17:15” 的时间字符串进行加减

2

转化为秒进行计算，再格式化为想要的格式。

3

试着转换成时间对象，然后操作时间，time-add / time-subtract。

4

有什么函数能转时间对象

5
6

(elisp) Time Parsing

转化时间需要完整的时间，从年到秒

7

我因为要用 ffmpeg 剪视频，所以写过几个函数，你看看能不能满足要求？

 (defun my//calculate-time-duration (start end)
   "Calculate seconds(format: SS) duration from START to END(format: \"HH:MM:SS\")."
   (-
     (let ((end-sum 0) (end-acc 0))
       (mapc
         (lambda (x)
           (if (and (<= (- x ?0) 9) (>= (- x ?0) 0))
             (setq end-acc (+ (* 10 end-acc) (- x ?0)))
             (setq end-sum (+ (* end-sum 60) end-acc)
                   end-acc 0)))
         end)
       (setq end-sum (+ (* end-sum 60) end-acc))
       end-sum)
     (let ((start-sum 0) (start-acc 0))
       (mapc
         (lambda (x)
           (if (and (<= (- x ?0) 9) (>= (- x ?0) 0))
             (setq start-acc (+ (* 10 start-acc) (- x ?0)))
             (setq start-sum (+ (* start-sum 60) start-acc)
                   start-acc 0)))
         start)
       (setq start-sum (+ (* start-sum 60) start-acc))
       start-sum)))

 (defun my//convert-second-to-time-format (second)
   "Convert input SECOND(SS) to time format(\"HH:MM:SS\")."
   (let (time)
     (dotimes (i 2)
       (setq time (concat (format ":%02d" (% second 60)) time)
             second (/ second 60)))
     (setq time (concat (format "%02d" second) time))
     time))

(my//calculate-time-duration "01:23" "45:56")
;; => 2673

(my//convert-second-to-time-format 2673)
;; => "00:44:33"

(my//calculate-time-duration "12:15" "01:12:34")
;; => 3619

(my//convert-second-to-time-format 3619)
;; => "01:00:19"
8 
(defun zerolee-time-subtract-timestamps (start-timestamp end-timestamp)
  "Subtract END-TIMESTAMP with START-TIMESTAMP."
  (let ((start 0)
        (end 0))
    (- (dolist (time (mapcar #'string-to-number (split-string end-timestamp ":")) end)
         (setq end (+ time (* end 60))))
       (dolist (time (mapcar #'string-to-number (split-string start-timestamp ":")) start)
         (setq start (+ time (* start 60)))))))

(defun zerolee-time-format (seconds)
  (let ((min (/ seconds 60)))
    (format "%02d:%02d:%02d" (/ min 60) (% min 60) (% seconds 60))))