Use , character instead of . for SRT output. (#197)

The SRT format uses the decimal comma character as the fractional separator rather than the decimal point character. Adjust format_timestamp and write_srt to specify the separator character.

See https://en.wikipedia.org/wiki/SubRip#:~:text=the%20fractional%20separator%20used%20is%20the%20comma%2C%20since%20the%20program%20was%20written%20in%20france.

whisper/utils.py

@@ -27,7 +27,7 @@ def compression_ratio(text) -> float:
     return len(text) / len(zlib.compress(text.encode("utf-8")))
 
 
-def format_timestamp(seconds: float, always_include_hours: bool = False):
+def format_timestamp(seconds: float, always_include_hours: bool = False, decimal_marker: str = '.'):
     assert seconds >= 0, "non-negative timestamp expected"
     milliseconds = round(seconds * 1000.0)
 
@@ -41,7 +41,7 @@ def format_timestamp(seconds: float, always_include_hours: bool = False):
     milliseconds -= seconds * 1_000
 
     hours_marker = f"{hours}:" if always_include_hours or hours > 0 else ""
-    return f"{hours_marker}{minutes:02d}:{seconds:02d}.{milliseconds:03d}"
+    return f"{hours_marker}{minutes:02d}:{seconds:02d}{decimal_marker}{milliseconds:03d}"
 
 
 def write_txt(transcript: Iterator[dict], file: TextIO):
@@ -79,8 +79,8 @@ def write_srt(transcript: Iterator[dict], file: TextIO):
         # write srt lines
         print(
             f"{i}\n"
-            f"{format_timestamp(segment['start'], always_include_hours=True)} --> "
-            f"{format_timestamp(segment['end'], always_include_hours=True)}\n"
+            f"{format_timestamp(segment['start'], always_include_hours=True, decimal_marker=',')} --> "
+            f"{format_timestamp(segment['end'], always_include_hours=True, decimal_marker=',')}\n"
             f"{segment['text'].strip().replace('-->', '->')}\n",
             file=file,
             flush=True,