lavc/videotoolboxenc: Enable a53cc by default.

libavcodec/videotoolboxenc.c

@@ -2311,7 +2311,7 @@ static const AVOption options[] = {
     { "frames_after", "Other frames will come after the frames in this session. This helps smooth concatenation issues.",
         OFFSET(frames_after), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VE },
 
-    { "a53cc", "Use A53 Closed Captions (if available)", OFFSET(a53_cc), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, VE },
+    { "a53cc", "Use A53 Closed Captions (if available)", OFFSET(a53_cc), AV_OPT_TYPE_BOOL, {.i64 = 1}, 0, 1, VE },
 
     { NULL },
 };