rtpbasepayload: add extensions property

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/5694>

girs/GstRtp-1.0.gir

@@ -3146,6 +3146,19 @@ the need to handle these extensions manually using the
 GstRTPBasePayload::request-extension: signal.</doc>
         <type name="gboolean" c:type="gboolean"/>
       </property>
+      <property name="extensions" version="1.24" transfer-ownership="none">
+        <doc xml:space="preserve" filename="../subprojects/gst-plugins-base/gst-libs/gst/rtp/gstrtpbasepayload.c">A list of already enabled RTP header extensions. This may be useful for finding
+out which extensions are already enabled (with add-extension signal) and picking a non-conflicting
+ID for a new extension that needs to be added on top of the existing ones.
+
+Note that the value returned by reading this property is not dynamically updated when the set of
+enabled extensions changes by any of existing action signals. Rather, it represents the current state
+at the time the property is read.
+
+Dynamic updates of this property can be received by subscribing to its corresponding "notify" signal, i.e.
+"notify::extensions".</doc>
+        <type name="Gst.ValueArray"/>
+      </property>
       <property name="max-ptime" writable="1" transfer-ownership="none">
         <type name="gint64" c:type="gint64"/>
       </property>

subprojects/gst-plugins-base/gst-libs/gst/rtp/gstrtpbasepayload.c

@@ -137,9 +137,12 @@ enum
   PROP_ONVIF_NO_RATE_CONTROL,
   PROP_SCALE_RTPTIME,
   PROP_AUTO_HEADER_EXTENSION,
+  PROP_EXTENSIONS,
   PROP_LAST
 };
 
+static GParamSpec *gst_rtp_base_payload_extensions_pspec;
+
 static void gst_rtp_base_payload_class_init (GstRTPBasePayloadClass * klass);
 static void gst_rtp_base_payload_init (GstRTPBasePayload * rtpbasepayload,
     gpointer g_class);
@@ -176,6 +179,8 @@ static gboolean gst_rtp_base_payload_negotiate (GstRTPBasePayload * payload);
 static void gst_rtp_base_payload_add_extension (GstRTPBasePayload * payload,
     GstRTPHeaderExtension * ext);
 static void gst_rtp_base_payload_clear_extensions (GstRTPBasePayload * payload);
+static void gst_rtp_base_payload_get_extensions (GstRTPBasePayload * payload,
+    GValue * out_value);
 
 static GstElementClass *parent_class = NULL;
 static gint private_offset = 0;
@@ -442,6 +447,33 @@ gst_rtp_base_payload_class_init (GstRTPBasePayloadClass * klass)
           DEFAULT_AUTO_HEADER_EXTENSION,
           G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
 
+  gst_rtp_base_payload_extensions_pspec = gst_param_spec_array ("extensions",
+      "RTP header extensions",
+      "A list of already enabled RTP header extensions",
+      g_param_spec_object ("extension", "RTP header extension",
+          "An already enabled RTP extension", GST_TYPE_RTP_HEADER_EXTENSION,
+          G_PARAM_READABLE | G_PARAM_STATIC_STRINGS),
+      G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
+
+  /**
+   * GstRTPBasePayload:extensions:
+   *
+   * A list of already enabled RTP header extensions. This may be useful for finding
+   * out which extensions are already enabled (with add-extension signal) and picking a non-conflicting
+   * ID for a new extension that needs to be added on top of the existing ones.
+   *
+   * Note that the value returned by reading this property is not dynamically updated when the set of
+   * enabled extensions changes by any of existing action signals. Rather, it represents the current state
+   * at the time the property is read.
+   *
+   * Dynamic updates of this property can be received by subscribing to its corresponding "notify" signal, i.e.
+   * "notify::extensions".
+   *
+   * Since: 1.24
+   */
+  g_object_class_install_property (G_OBJECT_CLASS (klass),
+      PROP_EXTENSIONS, gst_rtp_base_payload_extensions_pspec);
+
   /**
    * GstRTPBasePayload::add-extension:
    * @object: the #GstRTPBasePayload
@@ -1589,6 +1621,9 @@ gst_rtp_base_payload_add_extension (GstRTPBasePayload * payload,
   g_ptr_array_add (payload->priv->header_exts, gst_object_ref (ext));
   gst_pad_mark_reconfigure (GST_RTP_BASE_PAYLOAD_SRCPAD (payload));
   GST_OBJECT_UNLOCK (payload);
+
+  g_object_notify_by_pspec (G_OBJECT (payload),
+      gst_rtp_base_payload_extensions_pspec);
 }
 
 static void
@@ -1597,6 +1632,32 @@ gst_rtp_base_payload_clear_extensions (GstRTPBasePayload * payload)
   GST_OBJECT_LOCK (payload);
   g_ptr_array_set_size (payload->priv->header_exts, 0);
   GST_OBJECT_UNLOCK (payload);
+
+  g_object_notify_by_pspec (G_OBJECT (payload),
+      gst_rtp_base_payload_extensions_pspec);
+}
+
+static void
+gst_rtp_base_payload_get_extensions (GstRTPBasePayload * payload,
+    GValue * out_value)
+{
+  GPtrArray *extensions;
+  guint i;
+
+  GST_OBJECT_LOCK (payload);
+  extensions = payload->priv->header_exts;
+
+  for (i = 0; i < extensions->len; ++i) {
+    GValue value = G_VALUE_INIT;
+    g_value_init (&value, GST_TYPE_RTP_HEADER_EXTENSION);
+
+    g_value_set_object (&value, g_ptr_array_index (extensions, i));
+
+    gst_value_array_append_value (out_value, &value);
+    g_value_unset (&value);
+  }
+
+  GST_OBJECT_UNLOCK (payload);
 }
 
 typedef struct
@@ -2248,6 +2309,9 @@ gst_rtp_base_payload_get_property (GObject * object, guint prop_id,
     case PROP_AUTO_HEADER_EXTENSION:
       g_value_set_boolean (value, priv->auto_hdr_ext);
       break;
+    case PROP_EXTENSIONS:
+      gst_rtp_base_payload_get_extensions (rtpbasepayload, value);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;

subprojects/gst-plugins-base/tests/check/libs/rtpbasepayload.c

@@ -2310,6 +2310,61 @@ GST_START_TEST (rtp_base_payload_extensions_shrink_ext_data)
 }
 
 GST_END_TEST;
+
+GST_START_TEST (rtp_base_payload_extensions_get_enabled)
+{
+  GstElement *pay = GST_ELEMENT (rtp_dummy_pay_new ());
+  GstRTPHeaderExtension *ext = rtp_dummy_hdr_ext_new ();
+  GValue extensions = G_VALUE_INIT;
+  const GValue *returned_ext;
+
+  g_signal_emit_by_name (pay, "add-extension", ext, NULL);
+  g_object_get_property (G_OBJECT (pay), "extensions", &extensions);
+
+  fail_unless_equals_int (gst_value_array_get_size (&extensions), 1);
+
+  returned_ext = gst_value_array_get_value (&extensions, 0);
+
+  fail_unless (G_VALUE_HOLDS (returned_ext, GST_TYPE_RTP_HEADER_EXTENSION));
+  fail_unless (g_value_get_object (returned_ext) == ext);
+
+  g_value_unset (&extensions);
+  gst_object_unref (ext);
+  gst_object_unref (pay);
+}
+
+GST_END_TEST;
+
+static void
+on_extensions_changed (GObject * sender, GParamSpec * pspec,
+    guint * invocation_count)
+{
+  (void) sender;
+  (void) pspec;
+  (*invocation_count)++;
+}
+
+GST_START_TEST (rtp_base_payload_extensions_notify_on_change)
+{
+  GstElement *pay = GST_ELEMENT (rtp_dummy_pay_new ());
+  GstRTPHeaderExtension *ext = rtp_dummy_hdr_ext_new ();
+  guint invocation_count = 0;
+
+  g_signal_connect (pay, "notify::extensions",
+      G_CALLBACK (on_extensions_changed), &invocation_count);
+
+  g_signal_emit_by_name (pay, "add-extension", ext, NULL);
+  fail_unless_equals_int (invocation_count, 1);
+
+  g_signal_emit_by_name (pay, "clear-extensions", NULL);
+  fail_unless_equals_int (invocation_count, 2);
+
+  gst_object_unref (ext);
+  gst_object_unref (pay);
+}
+
+GST_END_TEST;
+
 static Suite *
 rtp_basepayloading_suite (void)
 {
@@ -2358,6 +2413,8 @@ rtp_basepayloading_suite (void)
   tcase_add_test (tc_chain, rtp_base_payload_caps_request_ignored);
   tcase_add_test (tc_chain, rtp_base_payload_extensions_in_output_caps);
   tcase_add_test (tc_chain, rtp_base_payload_extensions_shrink_ext_data);
+  tcase_add_test (tc_chain, rtp_base_payload_extensions_get_enabled);
+  tcase_add_test (tc_chain, rtp_base_payload_extensions_notify_on_change);
 
   return s;
 }