webvtt: Fix WebVTT timestamps.

* srt2vtt/webvtt.scm (write-time): Format time components with correct
  number of digits.

diff --git a/srt2vtt/webvtt.scm b/srt2vtt/webvtt.scm
index f4cd91b70d4d32a0c606d1387eeade681c4a58fd..046a5e72cad18bff10a1d69550975bfa2ad6446d 100644 (file)
--- a/srt2vtt/webvtt.scm
+++ b/srt2vtt/webvtt.scm
@@ -27,7 +27,7 @@
   "Write TIME as a WebVTT formatted timestamp to PORT."
   (match time
    ((h m s ms)
-    (format port "~a:~a:~a.~a" h m s ms))))
+    (format port "~2,'0d:~2,'0d:~2,'0d.~3,'0d" h m s ms))))
 
 (define (write-webvtt subtitle port)
   "Write SUBTITLE as a WebVTT formatted subtitle to PORT."