avformat/hlsenc: allow a custom SDT and PAT period

The default is not to write SDT and PAT periodically, only in the beginning of
every segment. After this patch the user might override this if needed.
Signed-off-by: Marton Balint <cus@passwd.hu>

libavformat/hlsenc.c

@@ -861,8 +861,8 @@ static int hls_mux_init(AVFormatContext *s, VariantStream *vs)
         /* We only require one PAT/PMT per segment. */
         char period[21];
         snprintf(period, sizeof(period), "%d", (INT_MAX / 2) - 1);
-        av_dict_set(&options, "sdt_period", period, 0);
-        av_dict_set(&options, "pat_period", period, 0);
+        av_dict_set(&options, "sdt_period", period, AV_DICT_DONT_OVERWRITE);
+        av_dict_set(&options, "pat_period", period, AV_DICT_DONT_OVERWRITE);
     }
     ret = avformat_init_output(oc, &options);
     remaining_options = av_dict_count(options);