multifdsink: add property to resend streamheaders

Adds a new property in multifdsink, resend-streamheader.

If this property is false, the multifdsink will not send the streamheader if
there's already one set for a particular client.

There are some formats in which every stream needs to start with a certain
blob, but you can't inject this blob at leisure. If the producer wants to
change the blob in question and sets in as the streamheader on the outgoing
buffers' caps, new clients of multifdsink will get the new streamheader, but
old clients will break, because they'll see the blob in the middle of the
stream.

The property is true by default, so existing code will not see any difference.

Fixes #578118.

gst/tcp/gstmultifdsink.c

@@ -181,6 +181,8 @@ enum
 #define DEFAULT_QOS_DSCP                -1
 #define DEFAULT_HANDLE_READ             TRUE
 
+#define DEFAULT_RESEND_STREAMHEADER      TRUE
+
 enum
 {
   PROP_0,
@@ -214,6 +216,8 @@ enum
 
   PROP_HANDLE_READ,
 
+  PROP_RESEND_STREAMHEADER,
+
   PROP_LAST
 };
 
@@ -490,8 +494,8 @@ gst_multi_fd_sink_class_init (GstMultiFdSinkClass * klass)
   g_object_class_install_property (gobject_class, PROP_QOS_DSCP,
       g_param_spec_int ("qos-dscp", "QoS diff srv code point",
           "Quality of Service, differentiated services code point (-1 default)",
-          -1, 63, DEFAULT_QOS_DSCP, G_PARAM_READWRITE));
-
+          -1, 63, DEFAULT_QOS_DSCP,
+          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
   /**
    * GstMultiFdSink::handle-read
    *
@@ -502,7 +506,19 @@ gst_multi_fd_sink_class_init (GstMultiFdSinkClass * klass)
   g_object_class_install_property (gobject_class, PROP_HANDLE_READ,
       g_param_spec_boolean ("handle-read", "Handle Read",
           "Handle client reads and discard the data",
-          DEFAULT_HANDLE_READ, G_PARAM_READWRITE));
+          DEFAULT_HANDLE_READ, G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+  /**
+   * GstMultiFdSink::resend-streamheader
+   *
+   * Resend the streamheaders to existing clients when they change.
+   *
+   * Since: 0.10.23
+   */
+  g_object_class_install_property (gobject_class, PROP_RESEND_STREAMHEADER,
+      g_param_spec_boolean ("resend-streamheader", "Resend streamheader",
+          "Resend the streamheader if it changes in the caps",
+          DEFAULT_RESEND_STREAMHEADER,
+          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
 
   /**
    * GstMultiFdSink::add:
@@ -695,6 +711,8 @@ gst_multi_fd_sink_init (GstMultiFdSink * this, GstMultiFdSinkClass * klass)
   this->qos_dscp = DEFAULT_QOS_DSCP;
   this->handle_read = DEFAULT_HANDLE_READ;
 
+  this->resend_streamheader = DEFAULT_RESEND_STREAMHEADER;
+
   this->header_flags = 0;
 }
 
@@ -1367,14 +1385,21 @@ gst_multi_fd_sink_client_queue_buffer (GstMultiFdSink * sink,
           send_streamheader = TRUE;
         } else {
           /* both old and new caps have streamheader set */
-          sh1 = gst_structure_get_value (s, "streamheader");
-          s = gst_caps_get_structure (caps, 0);
-          sh2 = gst_structure_get_value (s, "streamheader");
-          if (gst_value_compare (sh1, sh2) != GST_VALUE_EQUAL) {
+          if (!sink->resend_streamheader) {
             GST_DEBUG_OBJECT (sink,
-                "[fd %5d] new streamheader different from old, sending",
+                "[fd %5d] asked to not resend the streamheader, not sending",
                 client->fd.fd);
-            send_streamheader = TRUE;
+            send_streamheader = FALSE;
+          } else {
+            sh1 = gst_structure_get_value (s, "streamheader");
+            s = gst_caps_get_structure (caps, 0);
+            sh2 = gst_structure_get_value (s, "streamheader");
+            if (gst_value_compare (sh1, sh2) != GST_VALUE_EQUAL) {
+              GST_DEBUG_OBJECT (sink,
+                  "[fd %5d] new streamheader different from old, sending",
+                  client->fd.fd);
+              send_streamheader = TRUE;
+            }
           }
         }
       }
@@ -2685,6 +2710,9 @@ gst_multi_fd_sink_set_property (GObject * object, guint prop_id,
     case PROP_HANDLE_READ:
       multifdsink->handle_read = g_value_get_boolean (value);
       break;
+    case PROP_RESEND_STREAMHEADER:
+      multifdsink->resend_streamheader = g_value_get_boolean (value);
+      break;
 
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
@@ -2767,6 +2795,9 @@ gst_multi_fd_sink_get_property (GObject * object, guint prop_id, GValue * value,
     case PROP_HANDLE_READ:
       g_value_set_boolean (value, multifdsink->handle_read);
       break;
+    case PROP_RESEND_STREAMHEADER:
+      g_value_set_boolean (value, multifdsink->resend_streamheader);
+      break;
 
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);

gst/tcp/gstmultifdsink.h

@@ -235,6 +235,8 @@ struct _GstMultiFdSink {
   gint64 time_min;	/* min time to queue */
   gint   buffers_min;   /* min number of buffers to queue */
 
+  gboolean resend_streamheader; /* resend streamheader if it changes */
+
   /* stats */
   gint buffers_queued;  /* number of queued buffers */
   gint bytes_queued;    /* number of queued bytes */