rtpopuspay: set MARKER flag

Set MARKER flag on first buffer after DTX.

According to RFC 3551 section 4.1 the marker bit needs to be set on
"the first packet after a silence period during which packets have
not been transmitted contiguously".

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-good/-/merge_requests/967>

gst/rtp/gstrtpopuspay.c

@@ -131,6 +131,32 @@ gst_rtp_opus_pay_get_property (GObject * object,
   }
 }
 
+static GstStateChangeReturn
+gst_rtp_opus_pay_change_state (GstElement * element, GstStateChange transition)
+{
+  GstRtpOPUSPay *self = GST_RTP_OPUS_PAY (element);
+  GstStateChangeReturn ret;
+
+  switch (transition) {
+    case GST_STATE_CHANGE_READY_TO_PAUSED:
+      self->marker = TRUE;
+      break;
+    default:
+      break;
+  }
+
+  ret =
+      GST_ELEMENT_CLASS (gst_rtp_opus_pay_parent_class)->change_state (element,
+      transition);
+
+  switch (transition) {
+    default:
+      break;
+  }
+
+  return ret;
+}
+
 static void
 gst_rtp_opus_pay_class_init (GstRtpOPUSPayClass * klass)
 {
@@ -142,6 +168,8 @@ gst_rtp_opus_pay_class_init (GstRtpOPUSPayClass * klass)
   element_class = GST_ELEMENT_CLASS (klass);
   gobject_class = (GObjectClass *) klass;
 
+  element_class->change_state = gst_rtp_opus_pay_change_state;
+
   gstbasertppayload_class->set_caps = gst_rtp_opus_pay_setcaps;
   gstbasertppayload_class->get_caps = gst_rtp_opus_pay_getcaps;
   gstbasertppayload_class->handle_buffer = gst_rtp_opus_pay_handle_buffer;
@@ -305,6 +333,7 @@ gst_rtp_opus_pay_handle_buffer (GstRTPBasePayload * basepayload,
   if (self->dtx && gst_buffer_get_size (buffer) <= 2) {
     GST_LOG_OBJECT (self,
         "discard empty buffer as DTX is enabled: %" GST_PTR_FORMAT, buffer);
+    self->marker = TRUE;
     gst_buffer_unref (buffer);
     return GST_FLOW_OK;
   }
@@ -323,6 +352,11 @@ gst_rtp_opus_pay_handle_buffer (GstRTPBasePayload * basepayload,
   GST_BUFFER_DTS (outbuf) = dts;
   GST_BUFFER_DURATION (outbuf) = duration;
 
+  if (self->marker) {
+    GST_BUFFER_FLAG_SET (outbuf, GST_BUFFER_FLAG_MARKER);
+    self->marker = FALSE;
+  }
+
   /* Push out */
   return gst_rtp_base_payload_push (basepayload, outbuf);
 }

gst/rtp/gstrtpopuspay.h

@@ -46,6 +46,9 @@ struct _GstRtpOPUSPay
   GstRTPBasePayload payload;
 
   gboolean dtx;
+
+  /* if the next produced buffer should have the MARKER flag */
+  gboolean marker;
 };
 
 struct _GstRtpOPUSPayClass

tests/check/elements/rtp-payloading.c

@@ -1672,7 +1672,7 @@ GST_START_TEST (rtp_vorbis_renegotiate)
 GST_END_TEST;
 
 static guint16
-pull_rtp_buffer (GstHarness * h)
+pull_rtp_buffer (GstHarness * h, gboolean has_marker)
 {
   gint16 seq;
   GstBuffer *buf;
@@ -1685,6 +1685,11 @@ pull_rtp_buffer (GstHarness * h)
   seq = gst_rtp_buffer_get_seq (&rtp);
   gst_rtp_buffer_unmap (&rtp);
 
+  if (has_marker)
+    fail_unless (GST_BUFFER_FLAG_IS_SET (buf, GST_BUFFER_FLAG_MARKER));
+  else
+    fail_if (GST_BUFFER_FLAG_IS_SET (buf, GST_BUFFER_FLAG_MARKER));
+
   gst_buffer_unref (buf);
   return seq;
 }
@@ -1715,7 +1720,7 @@ test_rtp_opus_dtx (gboolean dtx)
       gst_buffer_new_wrapped (g_memdup (opus_frame, sizeof (opus_frame)),
       sizeof (opus_frame));
   fail_unless_equals_int (gst_harness_push (h, buf), GST_FLOW_OK);
-  seq = pull_rtp_buffer (h);
+  seq = pull_rtp_buffer (h, TRUE);
   expected_seq = seq + 1;
 
   /* push empty frame */
@@ -1728,7 +1733,7 @@ test_rtp_opus_dtx (gboolean dtx)
     buf = gst_harness_try_pull (h);
     fail_if (buf);
   } else {
-    seq = pull_rtp_buffer (h);
+    seq = pull_rtp_buffer (h, FALSE);
     fail_unless_equals_int (seq, expected_seq);
     expected_seq++;
   }
@@ -1738,7 +1743,7 @@ test_rtp_opus_dtx (gboolean dtx)
       gst_buffer_new_wrapped (g_memdup (opus_frame, sizeof (opus_frame)),
       sizeof (opus_frame));
   fail_unless_equals_int (gst_harness_push (h, buf), GST_FLOW_OK);
-  seq = pull_rtp_buffer (h);
+  seq = pull_rtp_buffer (h, dtx);
   fail_unless_equals_int (seq, expected_seq);
 
   gst_harness_teardown (h);