diff options
| -rwxr-xr-x | srt2vtt | 22 |
1 files changed, 22 insertions, 0 deletions
@@ -45,17 +45,23 @@ (define parse-time (let ((regexp (make-regexp "([0-9]+):([0-9]+):([0-9]+),([0-9]+)"))) (lambda (s) + "Parse the SubRip formatted timestamp in the string S into a 4 +element list. Valid input looks like '00:00:03.417'." (let ((match (regexp-exec regexp s))) (map (cut match:substring match <>) '(1 2 3 4)))))) (define parse-time-span (let ((regexp (make-regexp "([0-9:,]+) --> ([0-9:,]+)"))) (lambda (s) + "Parse the SubRip formatted time span in the string S and return +two values: the start time and the end time. Valid input looks like +'00:00:03.417 --> 00:00:04.936'." (let ((match (regexp-exec regexp s))) (values (parse-time (match:substring match 1)) (parse-time (match:substring match 2))))))) (define (read-sub-rip port) + "Read a SubRip formatted subtitle from PORT." (let-values (((id) (string->number (read-line port))) ((start end) (parse-time-span (read-line port))) ((lines) (let loop ((lines '())) @@ -66,6 +72,7 @@ (make-subtitle id start end lines))) (define (read-sub-rips port) + "Read all SubRip formatted subtitles from PORT." (reverse (let loop ((subs '())) (if (eof-object? (peek-char port)) @@ -73,11 +80,13 @@ (loop (cons (read-sub-rip port) subs)))))) (define (write-time time port) + "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)))) (define (write-web-vtt subtitle port) + "Write SUBTITLE as a WebVTT formatted subtitle to PORT." (match subtitle (($ <subtitle> id start end text) (format port "~a~%" id) @@ -89,10 +98,13 @@ (newline port)))) (define (write-web-vtts subtitles port) + "Write all SUBTITLES as WebVTT formatted subtitles to PORT." (format port "WEBVTT~%~%") (for-each (cut write-web-vtt <> port) subtitles)) (define (convert input-port output-port) + "Read the SubRip formatted subtitles from INPUT-PORT and write the +WebVTT equivalents to OUTPUT-PORT." (write-web-vtts (read-sub-rips input-port) output-port)) (define (show-help-and-exit) @@ -140,6 +152,12 @@ Convert SubRip formatted subtitles to WebVTT format.~%") (alist-cons 'output arg args))))) (define (make-call-with-port-or-file file-proc) + "Create a new procedure that accepts two arguments: a port or file, +and a procedure. When the returned procedure is called with a port as +the first argument, the second argument is simply applied with that +port. If the first argument is a string, the second argument is +applied with the port corresponding to the file name contained in the +string as opened by FILE-PROC." (lambda (port-or-file proc) (if (port? port-or-file) (proc port-or-file) @@ -152,6 +170,9 @@ Convert SubRip formatted subtitles to WebVTT format.~%") (make-call-with-port-or-file call-with-output-file)) (define (parse-opts args) + "Parse the list of ARGS and return a list of option/value pairs. +When an option isn't specified in ARGS, it defaults to the value in +'%default-args'." (args-fold args %options (lambda (opt name arg args) @@ -161,6 +182,7 @@ Convert SubRip formatted subtitles to WebVTT format.~%") %default-args)) (define (main args) + "srt2vtt entry point." (let ((opts (parse-opts args))) (call-with-port-or-input-file (assoc-ref opts 'input) (lambda (input-port) |