event: Add optional flags to the GAP event

This allows to signal the reason for the gap, for example missing data
like packet loss.

Based on a patch by Mikhail Fludkov <misha@pexip.com>

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/551>

gst/gstevent.c

@@ -826,6 +826,47 @@ gst_event_parse_gap (GstEvent * event, GstClockTime * timestamp,
       GST_QUARK (DURATION), GST_TYPE_CLOCK_TIME, duration, NULL);
 }
 
+/**
+ * gst_event_set_gap_flags:
+ * @event: a #GstEvent of type #GST_EVENT_GAP
+ * @flags: a #GstGapFlags
+ *
+ * Sets @flags on @event to give additional information about the reason for
+ * the #GST_EVENT_GAP.
+ *
+ * Since: 1.20
+ */
+void
+gst_event_set_gap_flags (GstEvent * event, GstGapFlags flags)
+{
+  g_return_if_fail (event != NULL);
+  g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_GAP);
+  g_return_if_fail (gst_event_is_writable (event));
+
+  gst_structure_id_set (GST_EVENT_STRUCTURE (event),
+      GST_QUARK (GAP_FLAGS), GST_TYPE_GAP_FLAGS, flags, NULL);
+}
+
+/**
+ * gst_event_parse_gap_flags:
+ * @event: a #GstEvent of type #GST_EVENT_GAP
+ * @flags: (out): a #GstGapFlags or %NULL
+ *
+ * Retrieve the gap flags that may have been set on a gap event with
+ * gst_event_set_gap_flags().
+ *
+ * Since: 1.20
+ */
+void
+gst_event_parse_gap_flags (GstEvent * event, GstGapFlags * flags)
+{
+  g_return_if_fail (event != NULL);
+  g_return_if_fail (GST_EVENT_TYPE (event) == GST_EVENT_GAP);
+
+  gst_structure_id_get (GST_EVENT_STRUCTURE (event),
+      GST_QUARK (GAP_FLAGS), GST_TYPE_GAP_FLAGS, flags, NULL);
+}
+
 /**
  * gst_event_new_caps:
  * @caps: (transfer none): a #GstCaps

gst/gstevent.h

@@ -404,6 +404,19 @@ typedef enum {
   GST_QOS_TYPE_THROTTLE        = 2
 } GstQOSType;
 
+/**
+ * GstGapFlags:
+ * @GST_GAP_FLAG_MISSING_DATA: The #GST_EVENT_GAP signals missing data,
+ *    for example because of packet loss.
+ *
+ * The different flags that can be set on #GST_EVENT_GAP events. See
+ * gst_event_set_gap_flags() for details.
+ *
+ * Since: 1.20
+ */
+typedef enum {
+  GST_GAP_FLAG_MISSING_DATA = (1<<0),
+} GstGapFlags;
 
 /**
  * GstEvent:
@@ -612,6 +625,14 @@ void            gst_event_parse_gap             (GstEvent     * event,
                                                  GstClockTime * timestamp,
                                                  GstClockTime * duration);
 
+GST_API
+void            gst_event_set_gap_flags           (GstEvent    * event,
+                                                   GstGapFlags   flags);
+
+GST_API
+void            gst_event_parse_gap_flags         (GstEvent    * event,
+                                                   GstGapFlags * flags);
+
 /* Caps events */
 
 GST_API

gst/gstquark.c

@@ -80,6 +80,7 @@ static const gchar *_quark_strings[] = {
   "GstEventInstantRateChange",
   "GstEventInstantRateSyncTime", "GstMessageInstantRateRequest",
   "upstream-running-time", "base", "offset", "plugin-api", "plugin-api-flags",
+  "gap-flags"
 };
 
 GQuark _priv_gst_quark_table[GST_QUARK_MAX];

gst/gstquark.h

@@ -230,7 +230,8 @@ typedef enum _GstQuarkId
   GST_QUARK_OFFSET = 199,
   GST_QUARK_PLUGIN_API = 200,
   GST_QUARK_PLUGIN_API_FLAGS = 201,
-  GST_QUARK_MAX = 202
+  GST_QUARK_GAP_FLAGS = 202,
+  GST_QUARK_MAX = 203
 } GstQuarkId;
 
 extern GQuark _priv_gst_quark_table[GST_QUARK_MAX];