[FFmpegSubtitlesConvertorPP] correctly update the extension (fixes #8444)

diff --git a/youtube_dl/postprocessor/ffmpeg.py b/youtube_dl/postprocessor/ffmpeg.py
index 6daa6a8b46babaade0f3d8e0518aa4ffb1bea727..05f2f06234d117a096d81eb01b482c85efad452e 100644 (file)
--- a/youtube_dl/postprocessor/ffmpeg.py
+++ b/youtube_dl/postprocessor/ffmpeg.py
@@ -523,7 +523,7 @@ class FFmpegSubtitlesConvertorPP(FFmpegPostProcessor):
 
             with io.open(new_file, 'rt', encoding='utf-8') as f:
                 subs[lang] = {
-                    'ext': ext,
+                    'ext': new_ext,
                     'data': f.read(),
                 }