diff --git a/subprojects/gst-plugins-good/tests/check/elements/rtphdrextsdes.c b/subprojects/gst-plugins-good/tests/check/elements/rtphdrextsdes.c
new file mode 100644
index 0000000000..d396101a5e
--- /dev/null
+++ b/subprojects/gst-plugins-good/tests/check/elements/rtphdrextsdes.c
@@ -0,0 +1,491 @@
+/* GStreamer
+ *
+ * unit test for RTP RFC 6464 Header Extensions
+ *
+ * Copyright (C) <2020-2021> Guillaume Desmottes <guillaume.desmottes@collabora.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include <gst/check/gstcheck.h>
+#include <gst/sdp/sdp.h>
+#include <gst/rtp/rtp.h>
+
+#define URN_MID "urn:ietf:params:rtp-hdrext:sdes:mid"
+#define URN_STREAM_ID "urn:ietf:params:rtp-hdrext:sdes:rtp-stream-id"
+#define URN_REPAIRED_STREAM_ID "urn:ietf:params:rtp-hdrext:sdes:repaired-rtp-stream-id"
+
+#define ALL_VALID_PROPERTY_ALPHANUMERIC "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVYZ"
+
+static void
+on_notify_val (GObject * ext, GParamSpec * pspec, char **out_val)
+{
+  char *property_name = *out_val;
+  g_object_get (ext, property_name, out_val, NULL);
+}
+
+static void
+read_write_extension (GstRTPHeaderExtension * read_ext,
+    GstRTPHeaderExtension * write_ext, GstRTPHeaderExtensionFlags flags,
+    const char *property_name, const char *val)
+{
+  GstBuffer *buffer;
+  gsize size, written;
+  guint8 *data;
+  char *got_val = NULL;
+  GstRTPHeaderExtensionFlags supported_flags = 0;
+  char *notify_signal_name;
+
+  buffer = gst_buffer_new ();
+
+  supported_flags = gst_rtp_header_extension_get_supported_flags (write_ext);
+  fail_unless (supported_flags & flags);
+
+  size = gst_rtp_header_extension_get_max_size (write_ext, buffer);
+  fail_unless (size > 0);
+  data = g_malloc0 (size);
+  fail_unless (data != NULL);
+
+  /* Write extension */
+  g_object_set (write_ext, property_name, val, NULL);
+  written =
+      gst_rtp_header_extension_write (write_ext, buffer,
+      flags, buffer, data, size);
+  fail_unless (written == strlen (val));
+
+  /* moving from no rid to a detected rid, fires the property notify signal */
+  notify_signal_name = g_strdup_printf ("notify::%s", property_name);
+  g_signal_connect (read_ext, notify_signal_name, G_CALLBACK (on_notify_val),
+      &got_val);
+  g_clear_pointer (&notify_signal_name, g_free);
+
+  got_val = (char *) property_name;
+  fail_unless (gst_rtp_header_extension_read (read_ext,
+          flags, data, written, buffer));
+  fail_unless_equals_string (got_val, val);
+  g_clear_pointer (&got_val, g_free);
+  got_val = (char *) property_name;
+  fail_unless (gst_rtp_header_extension_read (read_ext,
+          flags, data, written, buffer));
+  /* sequential val's don't notify */
+  fail_unless_equals_pointer (got_val, (void *) property_name);
+
+  /* attempting to write a NULL val, doesn't write anything */
+  got_val = (char *) property_name;
+  g_object_set (write_ext, property_name, NULL, NULL);
+  written =
+      gst_rtp_header_extension_write (write_ext, buffer,
+      flags, buffer, data, size);
+  fail_unless (written == 0);
+  /* reading an empty extension data does nothing */
+  fail_unless (gst_rtp_header_extension_read (read_ext,
+          flags, data, written, buffer));
+  fail_unless_equals_pointer (got_val, (void *) property_name);
+
+  g_clear_pointer (&data, g_free);
+  gst_clear_buffer (&buffer);
+  g_signal_handlers_disconnect_by_func (read_ext, on_notify_val, &got_val);
+}
+
+static void
+test_invalid_sdes_value (GstRTPHeaderExtension * ext, const char *property_name)
+{
+  char *val;
+
+  g_object_set (ext, property_name, NULL, NULL);
+
+  /* only alpahnumeric is supported */
+  /* test all the invalid boundary conditions in ascii */
+  g_object_set (ext, property_name, "/", NULL);
+  g_object_get (ext, property_name, &val, NULL);
+  fail_unless_equals_pointer (val, NULL);
+
+  g_object_set (ext, property_name, ":", NULL);
+  g_object_get (ext, property_name, &val, NULL);
+  fail_unless_equals_pointer (val, NULL);
+
+  g_object_set (ext, property_name, "@", NULL);
+  g_object_get (ext, property_name, &val, NULL);
+  fail_unless_equals_pointer (val, NULL);
+
+  g_object_set (ext, property_name, "[", NULL);
+  g_object_get (ext, property_name, &val, NULL);
+  fail_unless_equals_pointer (val, NULL);
+
+  g_object_set (ext, property_name, "`", NULL);
+  g_object_get (ext, property_name, &val, NULL);
+  fail_unless_equals_pointer (val, NULL);
+
+  g_object_set (ext, property_name, "{", NULL);
+  g_object_get (ext, property_name, &val, NULL);
+  fail_unless_equals_pointer (val, NULL);
+}
+
+GST_START_TEST (rtprfc8843_one_byte)
+{
+  GstRTPHeaderExtension *read_ext, *write_ext;
+
+  write_ext = gst_rtp_header_extension_create_from_uri (URN_MID);
+  fail_unless (write_ext != NULL);
+  gst_rtp_header_extension_set_id (write_ext, 1);
+
+  read_ext = gst_rtp_header_extension_create_from_uri (URN_MID);
+  fail_unless (read_ext != NULL);
+  gst_rtp_header_extension_set_id (read_ext, 1);
+
+  read_write_extension (read_ext, write_ext, GST_RTP_HEADER_EXTENSION_ONE_BYTE,
+      "mid", "0");
+  read_write_extension (read_ext, write_ext, GST_RTP_HEADER_EXTENSION_ONE_BYTE,
+      "mid", "01");
+
+  gst_object_unref (write_ext);
+  gst_object_unref (read_ext);
+}
+
+GST_END_TEST;
+
+GST_START_TEST (rtprfc8843_two_bytes)
+{
+  GstRTPHeaderExtension *read_ext, *write_ext;
+
+  write_ext = gst_rtp_header_extension_create_from_uri (URN_MID);
+  fail_unless (write_ext != NULL);
+  gst_rtp_header_extension_set_id (write_ext, 1);
+
+  read_ext = gst_rtp_header_extension_create_from_uri (URN_MID);
+  fail_unless (read_ext != NULL);
+  gst_rtp_header_extension_set_id (read_ext, 1);
+
+  read_write_extension (read_ext, write_ext, GST_RTP_HEADER_EXTENSION_TWO_BYTE,
+      "mid", "0");
+  read_write_extension (read_ext, write_ext, GST_RTP_HEADER_EXTENSION_TWO_BYTE,
+      "mid", "01");
+
+  gst_object_unref (write_ext);
+  gst_object_unref (read_ext);
+}
+
+GST_END_TEST;
+
+GST_START_TEST (rtprfc8843_long_mid_uses_two_byte)
+{
+  GstRTPHeaderExtension *write_ext;
+  GstRTPHeaderExtensionFlags flags;
+
+  write_ext = gst_rtp_header_extension_create_from_uri (URN_MID);
+  fail_unless (write_ext != NULL);
+  gst_rtp_header_extension_set_id (write_ext, 1);
+
+  g_object_set (write_ext, "mid", "0123456789abcdefg", NULL);
+  flags = gst_rtp_header_extension_get_supported_flags (write_ext);
+  fail_unless ((flags & GST_RTP_HEADER_EXTENSION_ONE_BYTE) == 0);
+  fail_unless ((flags & GST_RTP_HEADER_EXTENSION_TWO_BYTE) != 0);
+
+  gst_object_unref (write_ext);
+}
+
+GST_END_TEST;
+
+GST_START_TEST (rtprfc8843_invalid_property_set)
+{
+  GstRTPHeaderExtension *write_ext;
+
+  write_ext = gst_rtp_header_extension_create_from_uri (URN_MID);
+  fail_unless (write_ext != NULL);
+  gst_rtp_header_extension_set_id (write_ext, 1);
+
+  test_invalid_sdes_value (write_ext, "mid");
+
+  gst_object_unref (write_ext);
+}
+
+GST_END_TEST;
+
+GST_START_TEST (rtprfc8843_mid_in_caps)
+{
+  GstRTPHeaderExtension *write_ext;
+  GstCaps *caps;
+  GstStructure *s;
+
+#define MID_VAL "0"
+
+  write_ext = gst_rtp_header_extension_create_from_uri (URN_MID);
+  fail_unless (write_ext != NULL);
+  gst_rtp_header_extension_set_id (write_ext, 1);
+
+  g_object_set (write_ext, "mid", MID_VAL, NULL);
+
+  caps = gst_caps_new_empty_simple ("application/x-rtp");
+  gst_rtp_header_extension_set_caps_from_attributes (write_ext, caps);
+
+  s = gst_caps_get_structure (caps, 0);
+  fail_unless_equals_string (gst_structure_get_string (s, "a-mid"), MID_VAL);
+
+  gst_clear_caps (&caps);
+  gst_object_unref (write_ext);
+}
+
+GST_END_TEST;
+
+GST_START_TEST (rtprfc8843_all_valid_values)
+{
+  GstRTPHeaderExtension *write_ext;
+  char *mid = NULL;
+
+  write_ext = gst_rtp_header_extension_create_from_uri (URN_MID);
+  fail_unless (write_ext != NULL);
+  gst_rtp_header_extension_set_id (write_ext, 1);
+
+  g_object_set (write_ext, "mid", ALL_VALID_PROPERTY_ALPHANUMERIC, NULL);
+  g_object_get (write_ext, "mid", &mid, NULL);
+  fail_unless_equals_string (mid, ALL_VALID_PROPERTY_ALPHANUMERIC);
+
+  gst_object_unref (write_ext);
+  g_clear_pointer (&mid, g_free);
+}
+
+GST_END_TEST;
+
+GST_START_TEST (rtprfc8852_stream_id_one_byte)
+{
+  GstRTPHeaderExtension *read_ext, *write_ext;
+
+  write_ext = gst_rtp_header_extension_create_from_uri (URN_STREAM_ID);
+  fail_unless (write_ext != NULL);
+  gst_rtp_header_extension_set_id (write_ext, 1);
+
+  read_ext = gst_rtp_header_extension_create_from_uri (URN_STREAM_ID);
+  fail_unless (read_ext != NULL);
+  gst_rtp_header_extension_set_id (read_ext, 1);
+
+  read_write_extension (read_ext, write_ext, GST_RTP_HEADER_EXTENSION_ONE_BYTE,
+      "rid", "0");
+  read_write_extension (read_ext, write_ext, GST_RTP_HEADER_EXTENSION_ONE_BYTE,
+      "rid", "01");
+
+  gst_object_unref (write_ext);
+  gst_object_unref (read_ext);
+}
+
+GST_END_TEST;
+
+GST_START_TEST (rtprfc8852_stream_id_two_bytes)
+{
+  GstRTPHeaderExtension *read_ext, *write_ext;
+
+  write_ext = gst_rtp_header_extension_create_from_uri (URN_STREAM_ID);
+  fail_unless (write_ext != NULL);
+  gst_rtp_header_extension_set_id (write_ext, 1);
+
+  read_ext = gst_rtp_header_extension_create_from_uri (URN_STREAM_ID);
+  fail_unless (read_ext != NULL);
+  gst_rtp_header_extension_set_id (read_ext, 1);
+
+  read_write_extension (read_ext, write_ext, GST_RTP_HEADER_EXTENSION_TWO_BYTE,
+      "rid", "0");
+  read_write_extension (read_ext, write_ext, GST_RTP_HEADER_EXTENSION_TWO_BYTE,
+      "rid", "01");
+
+  gst_object_unref (write_ext);
+  gst_object_unref (read_ext);
+}
+
+GST_END_TEST;
+
+GST_START_TEST (rtprfc8852_stream_id_long_rid_uses_two_byte)
+{
+  GstRTPHeaderExtension *write_ext;
+  GstRTPHeaderExtensionFlags flags;
+
+  write_ext = gst_rtp_header_extension_create_from_uri (URN_STREAM_ID);
+  fail_unless (write_ext != NULL);
+  gst_rtp_header_extension_set_id (write_ext, 1);
+
+  g_object_set (write_ext, "rid", "0123456789abcdefg", NULL);
+  flags = gst_rtp_header_extension_get_supported_flags (write_ext);
+  fail_unless ((flags & GST_RTP_HEADER_EXTENSION_ONE_BYTE) == 0);
+  fail_unless ((flags & GST_RTP_HEADER_EXTENSION_TWO_BYTE) != 0);
+
+  gst_object_unref (write_ext);
+}
+
+GST_END_TEST;
+
+GST_START_TEST (rtprfc8852_stream_id_invalid_property_set)
+{
+  GstRTPHeaderExtension *write_ext;
+
+  write_ext = gst_rtp_header_extension_create_from_uri (URN_STREAM_ID);
+  fail_unless (write_ext != NULL);
+  gst_rtp_header_extension_set_id (write_ext, 1);
+
+  test_invalid_sdes_value (write_ext, "rid");
+
+  gst_object_unref (write_ext);
+}
+
+GST_END_TEST;
+
+GST_START_TEST (rtprfc8852_stream_id_all_valid_values)
+{
+  GstRTPHeaderExtension *write_ext;
+  char *rid = NULL;
+
+  write_ext = gst_rtp_header_extension_create_from_uri (URN_STREAM_ID);
+  fail_unless (write_ext != NULL);
+  gst_rtp_header_extension_set_id (write_ext, 1);
+
+  g_object_set (write_ext, "rid", ALL_VALID_PROPERTY_ALPHANUMERIC, NULL);
+  g_object_get (write_ext, "rid", &rid, NULL);
+  fail_unless_equals_string (rid, ALL_VALID_PROPERTY_ALPHANUMERIC);
+
+  gst_object_unref (write_ext);
+  g_clear_pointer (&rid, g_free);
+}
+
+GST_END_TEST;
+
+GST_START_TEST (rtprfc8852_repaired_stream_id_one_byte)
+{
+  GstRTPHeaderExtension *read_ext, *write_ext;
+
+  write_ext = gst_rtp_header_extension_create_from_uri (URN_REPAIRED_STREAM_ID);
+  fail_unless (write_ext != NULL);
+  gst_rtp_header_extension_set_id (write_ext, 1);
+
+  read_ext = gst_rtp_header_extension_create_from_uri (URN_REPAIRED_STREAM_ID);
+  fail_unless (read_ext != NULL);
+  gst_rtp_header_extension_set_id (read_ext, 1);
+
+  read_write_extension (read_ext, write_ext, GST_RTP_HEADER_EXTENSION_ONE_BYTE,
+      "rid", "0");
+  read_write_extension (read_ext, write_ext, GST_RTP_HEADER_EXTENSION_ONE_BYTE,
+      "rid", "01");
+
+  gst_object_unref (write_ext);
+  gst_object_unref (read_ext);
+}
+
+GST_END_TEST;
+
+GST_START_TEST (rtprfc8852_repaired_stream_id_two_bytes)
+{
+  GstRTPHeaderExtension *read_ext, *write_ext;
+
+  write_ext = gst_rtp_header_extension_create_from_uri (URN_REPAIRED_STREAM_ID);
+  fail_unless (write_ext != NULL);
+  gst_rtp_header_extension_set_id (write_ext, 1);
+
+  read_ext = gst_rtp_header_extension_create_from_uri (URN_REPAIRED_STREAM_ID);
+  fail_unless (read_ext != NULL);
+  gst_rtp_header_extension_set_id (read_ext, 1);
+
+  read_write_extension (read_ext, write_ext, GST_RTP_HEADER_EXTENSION_TWO_BYTE,
+      "rid", "0");
+  read_write_extension (read_ext, write_ext, GST_RTP_HEADER_EXTENSION_TWO_BYTE,
+      "rid", "01");
+
+  gst_object_unref (write_ext);
+  gst_object_unref (read_ext);
+}
+
+GST_END_TEST;
+
+GST_START_TEST (rtprfc8852_repaired_stream_id_long_rid_uses_two_byte)
+{
+  GstRTPHeaderExtension *write_ext;
+  GstRTPHeaderExtensionFlags flags;
+
+  write_ext = gst_rtp_header_extension_create_from_uri (URN_REPAIRED_STREAM_ID);
+  fail_unless (write_ext != NULL);
+  gst_rtp_header_extension_set_id (write_ext, 1);
+
+  g_object_set (write_ext, "rid", "0123456789abcdefg", NULL);
+  flags = gst_rtp_header_extension_get_supported_flags (write_ext);
+  fail_unless ((flags & GST_RTP_HEADER_EXTENSION_ONE_BYTE) == 0);
+  fail_unless ((flags & GST_RTP_HEADER_EXTENSION_TWO_BYTE) != 0);
+
+  gst_object_unref (write_ext);
+}
+
+GST_END_TEST;
+
+GST_START_TEST (rtprfc8852_repaired_stream_id_invalid_property_set)
+{
+  GstRTPHeaderExtension *write_ext;
+
+  write_ext = gst_rtp_header_extension_create_from_uri (URN_REPAIRED_STREAM_ID);
+  fail_unless (write_ext != NULL);
+  gst_rtp_header_extension_set_id (write_ext, 1);
+
+  test_invalid_sdes_value (write_ext, "rid");
+
+  gst_object_unref (write_ext);
+}
+
+GST_END_TEST;
+
+GST_START_TEST (rtprfc8852_repaired_stream_id_all_valid_values)
+{
+  GstRTPHeaderExtension *write_ext;
+  char *rid = NULL;
+
+  write_ext = gst_rtp_header_extension_create_from_uri (URN_REPAIRED_STREAM_ID);
+  fail_unless (write_ext != NULL);
+  gst_rtp_header_extension_set_id (write_ext, 1);
+
+  g_object_set (write_ext, "rid", ALL_VALID_PROPERTY_ALPHANUMERIC, NULL);
+  g_object_get (write_ext, "rid", &rid, NULL);
+  fail_unless_equals_string (rid, ALL_VALID_PROPERTY_ALPHANUMERIC);
+
+  gst_object_unref (write_ext);
+  g_clear_pointer (&rid, g_free);
+}
+
+GST_END_TEST;
+
+static Suite *
+rtprfc6464_suite (void)
+{
+  Suite *s = suite_create ("rtphdrextsdes");
+  TCase *tc_chain = tcase_create ("general");
+
+  suite_add_tcase (s, tc_chain);
+
+  tcase_add_test (tc_chain, rtprfc8843_one_byte);
+  tcase_add_test (tc_chain, rtprfc8843_two_bytes);
+  tcase_add_test (tc_chain, rtprfc8843_long_mid_uses_two_byte);
+  tcase_add_test (tc_chain, rtprfc8843_invalid_property_set);
+  tcase_add_test (tc_chain, rtprfc8843_all_valid_values);
+  tcase_add_test (tc_chain, rtprfc8843_mid_in_caps);
+
+  tcase_add_test (tc_chain, rtprfc8852_stream_id_one_byte);
+  tcase_add_test (tc_chain, rtprfc8852_stream_id_two_bytes);
+  tcase_add_test (tc_chain, rtprfc8852_stream_id_long_rid_uses_two_byte);
+  tcase_add_test (tc_chain, rtprfc8852_stream_id_invalid_property_set);
+  tcase_add_test (tc_chain, rtprfc8852_stream_id_all_valid_values);
+
+  tcase_add_test (tc_chain, rtprfc8852_repaired_stream_id_one_byte);
+  tcase_add_test (tc_chain, rtprfc8852_repaired_stream_id_two_bytes);
+  tcase_add_test (tc_chain,
+      rtprfc8852_repaired_stream_id_long_rid_uses_two_byte);
+  tcase_add_test (tc_chain, rtprfc8852_repaired_stream_id_invalid_property_set);
+  tcase_add_test (tc_chain, rtprfc8852_repaired_stream_id_all_valid_values);
+
+  return s;
+}
+
+GST_CHECK_MAIN (rtprfc6464)
diff --git a/subprojects/gst-plugins-good/tests/check/meson.build b/subprojects/gst-plugins-good/tests/check/meson.build
index 1920768091..93cd2673a8 100644
--- a/subprojects/gst-plugins-good/tests/check/meson.build
+++ b/subprojects/gst-plugins-good/tests/check/meson.build
@@ -74,6 +74,7 @@ good_tests = [
   [ 'elements/rtpcollision' ],
   [ 'elements/rtpfunnel' ],
   [ 'elements/rtphdrextclientaudiolevel', false, [gstsdp_dep, gstaudio_dep] ],
+  [ 'elements/rtphdrextsdes', false, [gstrtp_dep, gstsdp_dep] ],
   [ 'elements/rtpjitterbuffer' ],
   [ 'elements/rtpjpeg' ],