diff --git a/src/client/pv-stream.c b/src/client/pv-stream.c
index 77df500e5..c4bd7ad70 100644
--- a/src/client/pv-stream.c
+++ b/src/client/pv-stream.c
@@ -688,13 +688,16 @@ on_socket_condition (GSocket       *socket,
       if (priv->info.message)
         g_object_unref (priv->info.message);
 
+      if (num_messages == 0)
+        break;
+
       priv->info.flags = msg.flags;
       priv->info.seq = msg.seq;
       priv->info.pts = msg.pts;
       priv->info.dts_offset = msg.dts_offset;
       priv->info.offset = msg.offset;
       priv->info.size = msg.size;
-      priv->info.message = num_messages > 0 ? messages[0] : NULL;
+      priv->info.message = messages[0];
 
       g_signal_emit (stream, signals[SIGNAL_NEW_BUFFER], 0, NULL);
       break;
diff --git a/src/gst/gstpvsink.c b/src/gst/gstpvsink.c
index 1a2cc6414..0ae63df76 100644
--- a/src/gst/gstpvsink.c
+++ b/src/gst/gstpvsink.c
@@ -257,6 +257,21 @@ gst_pulsevideo_sink_setcaps (GstBaseSink * bsink, GstCaps * caps)
   g_mutex_unlock (&pvsink->lock);
 
   pv_stream_start (pvsink->stream, format, PV_STREAM_MODE_BUFFER);
+
+  g_mutex_lock (&pvsink->lock);
+  while (TRUE) {
+    PvStreamState state = pv_stream_get_state (pvsink->stream);
+
+    if (state == PV_STREAM_STATE_STREAMING)
+      break;
+
+    if (state == PV_STREAM_STATE_ERROR)
+      goto connect_error;
+
+    g_cond_wait (&pvsink->cond, &pvsink->lock);
+  }
+  g_mutex_unlock (&pvsink->lock);
+
   pvsink->negotiated = TRUE;
 
   return TRUE;
diff --git a/src/gst/gstpvsrc.c b/src/gst/gstpvsrc.c
index 578127bdf..0fdc072e4 100644
--- a/src/gst/gstpvsrc.c
+++ b/src/gst/gstpvsrc.c
@@ -368,8 +368,16 @@ gst_pulsevideo_src_create (GstPushSrc * psrc, GstBuffer ** buffer)
     goto not_negotiated;
 
   g_mutex_lock (&pvsrc->lock);
-  g_cond_wait (&pvsrc->cond, &pvsrc->lock);
-  pv_stream_capture_buffer (pvsrc->stream, &info);
+  while (TRUE) {
+    g_cond_wait (&pvsrc->cond, &pvsrc->lock);
+
+    if (pv_stream_get_state (pvsrc->stream) != PV_STREAM_STATE_STREAMING)
+      goto streaming_stopped;
+
+    pv_stream_capture_buffer (pvsrc->stream, &info);
+    if (info.message != NULL)
+      break;
+  }
   g_mutex_unlock (&pvsrc->lock);
 
   *buffer = gst_buffer_new ();
@@ -393,6 +401,11 @@ not_negotiated:
   {
     return GST_FLOW_NOT_NEGOTIATED;
   }
+streaming_stopped:
+  {
+    g_mutex_unlock (&pvsrc->lock);
+    return GST_FLOW_FLUSHING;
+  }
 }
 
 static gboolean
diff --git a/src/modules/v4l2/pv-v4l2-source.c b/src/modules/v4l2/pv-v4l2-source.c
index 1d6fb3175..b21208577 100644
--- a/src/modules/v4l2/pv-v4l2-source.c
+++ b/src/modules/v4l2/pv-v4l2-source.c
@@ -141,7 +141,20 @@ v4l2_set_state (PvSource *source, PvSourceState state)
 static GBytes *
 v4l2_get_capabilities (PvSource *source, GBytes *filter)
 {
-  return NULL;
+  GstCaps *caps, *cfilter;
+  gchar *str;
+
+  cfilter = gst_caps_from_string (g_bytes_get_data (filter, NULL));
+  if (cfilter == NULL)
+    return NULL;
+
+  caps = collect_caps (source, cfilter);
+  if (caps == NULL)
+    return NULL;
+
+  str = gst_caps_to_string (caps);
+
+  return g_bytes_new_take (str, strlen (str) + 1);
 }
 
 static void
diff --git a/src/server/pv-client-source.c b/src/server/pv-client-source.c
index f6bb74bfe..f7097e136 100644
--- a/src/server/pv-client-source.c
+++ b/src/server/pv-client-source.c
@@ -17,6 +17,7 @@
  * Boston, MA 02110-1301, USA.
  */
 
+#include <string.h>
 #include <gst/gst.h>
 #include <gio/gio.h>
 
@@ -92,18 +93,20 @@ setup_pipeline (PvClientSource *source)
   gst_object_unref (bus);
 }
 
-static void
-collect_capabilities (PvSource * source)
+static GstCaps *
+collect_caps (PvSource * source, GstCaps *filter)
 {
   PvClientSourcePrivate *priv = PV_CLIENT_SOURCE (source)->priv;
   GstCaps *res;
   GstQuery *query;
 
   query = gst_query_new_caps (NULL);
-  gst_element_query (priv->src, query);
+  gst_element_query (priv->filter, query);
   gst_query_parse_caps_result (query, &res);
-  g_print ("client source caps:  %s\n", gst_caps_to_string (res));
+  gst_caps_ref (res);
   gst_query_unref (query);
+
+  return res;
 }
 
 static gboolean
@@ -118,7 +121,6 @@ client_set_state (PvSource *source, PvSourceState state)
 
     case PV_SOURCE_STATE_INIT:
       gst_element_set_state (priv->pipeline, GST_STATE_READY);
-      collect_capabilities (source);
       break;
 
     case PV_SOURCE_STATE_IDLE:
@@ -139,7 +141,20 @@ client_set_state (PvSource *source, PvSourceState state)
 static GBytes *
 client_get_capabilities (PvSource *source, GBytes *filter)
 {
-  return NULL;
+  GstCaps *caps, *cfilter;
+  gchar *str;
+
+  cfilter = gst_caps_from_string (g_bytes_get_data (filter, NULL));
+  if (cfilter == NULL)
+    return NULL;
+
+  caps = collect_caps (source, cfilter);
+  if (caps == NULL)
+    return NULL;
+
+  str = gst_caps_to_string (caps);
+
+  return g_bytes_new_take (str, strlen (str) + 1);
 }
 
 static void
@@ -151,31 +166,34 @@ on_socket_notify (GObject    *gobject,
   PvClientSourcePrivate *priv = source->priv;
   GSocket *socket;
   guint num_handles;
-  GBytes *requested_format;
 
   g_object_get (gobject, "socket", &socket, NULL);
 
   g_print ("source socket %p\n", socket);
 
   if (socket == NULL) {
-    if (priv->socket)
-      g_signal_emit_by_name (priv->sink, "remove", priv->socket);
+    GSocket *prev_socket = g_object_get_data (gobject, "last-socket");
+    if (prev_socket) {
+      g_signal_emit_by_name (priv->sink, "remove", prev_socket);
+    }
   } else {
     g_signal_emit_by_name (priv->sink, "add", socket);
   }
-  priv->socket = socket;
-
-  /* force format on input */
-  g_object_get (priv->input, "format", &requested_format, NULL);
-  g_assert (requested_format != NULL);
-  g_print ("final format %s\n", (gchar *) g_bytes_get_data (requested_format, NULL));
-  g_object_set (gobject, "format", requested_format, NULL);
-  g_bytes_unref (requested_format);
+  g_object_set_data (gobject, "last-socket", socket);
 
   g_object_get (priv->sink, "num-handles", &num_handles, NULL);
+  g_print ("num handles %d\n", num_handles);
   if (num_handles == 0) {
     gst_element_set_state (priv->pipeline, GST_STATE_READY);
-  } else {
+  } else if (socket) {
+    GBytes *format;
+
+    /* suggest what we provide */
+    g_object_get (priv->input, "format", &format, NULL);
+    g_print ("final format %s\n", (gchar *) g_bytes_get_data (format, NULL));
+    g_object_set (gobject, "format", format, NULL);
+    g_bytes_unref (format);
+
     gst_element_set_state (priv->pipeline, GST_STATE_PLAYING);
   }
 }
@@ -237,17 +255,22 @@ on_input_socket_notify (GObject    *gobject,
   g_object_get (gobject, "socket", &socket, NULL);
   g_print ("input socket %p\n", socket);
 
-  g_object_get (gobject, "requested-format", &requested_format, NULL);
-  g_assert (requested_format != NULL);
-  g_print ("final format %s\n", (gchar *) g_bytes_get_data (requested_format, NULL));
-  g_object_set (gobject, "format", requested_format, NULL);
-
-  caps = gst_caps_from_string (g_bytes_get_data (requested_format, NULL));
-  g_assert (caps != NULL);
-  g_object_set (priv->filter, "caps", caps, NULL);
-  gst_caps_unref (caps);
-  g_bytes_unref (requested_format);
+  if (socket) {
+    /* requested format is final format */
+    g_object_get (gobject, "requested-format", &requested_format, NULL);
+    g_assert (requested_format != NULL);
+    g_print ("final format %s\n", (gchar *) g_bytes_get_data (requested_format, NULL));
+    g_object_set (gobject, "format", requested_format, NULL);
 
+    /* and set as caps on the filter */
+    caps = gst_caps_from_string (g_bytes_get_data (requested_format, NULL));
+    g_assert (caps != NULL);
+    g_object_set (priv->filter, "caps", caps, NULL);
+    gst_caps_unref (caps);
+    g_bytes_unref (requested_format);
+  } else {
+    g_object_set (priv->filter, "caps", NULL, NULL);
+  }
   g_object_set (priv->src, "socket", socket, NULL);
 }