subparse: Handle GAP events before buffers

Make sure we did initial negotiation and segment pushing if we get GAP events
before buffers.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1903>

diff --git a/subprojects/gst-plugins-base/gst/subparse/gstsubparse.c b/subprojects/gst-plugins-base/gst/subparse/gstsubparse.c
index eaae3cf..d123624 100644 (file)
--- a/subprojects/gst-plugins-base/gst/subparse/gstsubparse.c
+++ b/subprojects/gst-plugins-base/gst/subparse/gstsubparse.c
@@ -1599,26 +1599,10 @@ done:
 }
 
 static GstFlowReturn
-handle_buffer (GstSubParse * self, GstBuffer * buf)
+check_initial_events (GstSubParse * self)
 {
-  GstFlowReturn ret = GST_FLOW_OK;
-  gchar *line, *subtitle;
   gboolean need_tags = FALSE;
 
-  if (self->first_buffer) {
-    GstMapInfo map;
-
-    gst_buffer_map (buf, &map, GST_MAP_READ);
-    self->detected_encoding =
-        gst_sub_parse_detect_encoding ((gchar *) map.data, map.size);
-    gst_buffer_unmap (buf, &map);
-    self->first_buffer = FALSE;
-    self->state.fps_n = self->fps_n;
-    self->state.fps_d = self->fps_d;
-  }
-
-  feed_textbuf (self, buf);
-
   /* make sure we know the format */
   if (G_UNLIKELY (self->parser_type == GST_SUB_PARSE_FORMAT_UNKNOWN)) {
     GstCaps *preferred;
@@ -1657,6 +1641,35 @@ handle_buffer (GstSubParse * self, GstBuffer * buf)
     }
   }
 
+  return GST_FLOW_OK;
+}
+
+static GstFlowReturn
+handle_buffer (GstSubParse * self, GstBuffer * buf)
+{
+  GstFlowReturn ret = GST_FLOW_OK;
+  gchar *line, *subtitle;
+
+  GST_DEBUG_OBJECT (self, "%" GST_PTR_FORMAT, buf);
+
+  if (self->first_buffer) {
+    GstMapInfo map;
+
+    gst_buffer_map (buf, &map, GST_MAP_READ);
+    self->detected_encoding =
+        gst_sub_parse_detect_encoding ((gchar *) map.data, map.size);
+    gst_buffer_unmap (buf, &map);
+    self->first_buffer = FALSE;
+    self->state.fps_n = self->fps_n;
+    self->state.fps_d = self->fps_d;
+  }
+
+  feed_textbuf (self, buf);
+
+  ret = check_initial_events (self);
+  if (ret != GST_FLOW_OK)
+    return ret;
+
   while (!self->flushing && (line = get_next_line (self))) {
     guint offset = 0;
 
@@ -1807,6 +1820,16 @@ gst_sub_parse_sink_event (GstPad * pad, GstObject * parent, GstEvent * event)
       self->need_segment = TRUE;
       break;
     }
+    case GST_EVENT_GAP:
+    {
+      ret = check_initial_events (self);
+      if (ret == GST_FLOW_OK) {
+        ret = gst_pad_event_default (pad, parent, event);
+      } else {
+        gst_event_unref (event);
+      }
+      break;
+    }
     case GST_EVENT_FLUSH_START:
     {
       self->flushing = TRUE;