MMFMWK-7911 fix one stream with subtitles seek time out

Reduce the gap of subtile stream's gap event from 1s to 200ms to avoid video stream
being blocked. The impact of the gap is severe for sparse streams.

Signed-off-by: Hou Qi <qi.hou@nxp.com>
diff --git a/plugins/aiurdemux/aiurdemux.c b/plugins/aiurdemux/aiurdemux.c
index 738e4bc..74a05aa 100755
--- a/plugins/aiurdemux/aiurdemux.c
+++ b/plugins/aiurdemux/aiurdemux.c
@@ -342,7 +342,7 @@
 
 
 
-
+#define SUBTITLE_GAP_INTERVAL (GST_SECOND/5)
 
 #define AIUR_MEDIATYPE2STR(media) \
     (((media)==MEDIA_VIDEO)?"video":(((media)==MEDIA_AUDIO)?"audio":"subtitle"))
@@ -2783,16 +2783,18 @@
 
       GST_INFO ("min_time=%lld\n", min_time);
 
+      /* sutitle gap is used to inform the downstream elements that there is no data for a
+       * certain amount of time, SUBTITLE_GAP_INTERVAL is set to avoid video being blocked. */
       if (GST_CLOCK_TIME_IS_VALID(stream->time_position) &&
           min_time != G_MAXINT64 &&
-          stream->time_position + GST_SECOND <= min_time) {
+          stream->time_position + SUBTITLE_GAP_INTERVAL <= min_time) {
         if (stream->new_segment) {
           aiurdemux_send_stream_newsegment (demux, stream);
         }
 
-        GstEvent *gap = gst_event_new_gap (stream->time_position, GST_SECOND);
+        GstEvent *gap = gst_event_new_gap (stream->time_position, SUBTITLE_GAP_INTERVAL);
         stream->last_start = stream->time_position;
-        stream->last_stop = stream->time_position + GST_SECOND;
+        stream->last_stop = stream->time_position + SUBTITLE_GAP_INTERVAL;
 
         gst_pad_push_event (stream->pad, gap);
         GST_INFO ("TEXT GAP event sent %d, time_position=%lld, "