Implement negotiation

Use generic byte blobs for formats. We currently use them to store
gstreamer caps but we could also use them to exchange serialized
GVariants if we want.

Make properties a variant dictionary

src/modules/v4l2/pv-v4l2-source.c

@@ -17,6 +17,7 @@
  * Boston, MA 02110-1301, USA.
  */
 
+#include <string.h>
 #include <gst/gst.h>
 #include <gio/gio.h>
 
@@ -32,6 +33,8 @@ struct _PvV4l2SourcePrivate
   GstElement *filter;
   GstElement *sink;
 
+  GstCaps *possible_formats;
+
   GSocket *socket;
 };
 
@@ -90,18 +93,20 @@ setup_pipeline (PvV4l2Source *source)
   gst_object_unref (bus);
 }
 
-static void
-collect_capabilities (PvSource * source)
+static GstCaps *
+collect_caps (PvSource * source, GstCaps *filter)
 {
   PvV4l2SourcePrivate *priv = PV_V4L2_SOURCE (source)->priv;
   GstCaps *res;
   GstQuery *query;
 
-  query = gst_query_new_caps (NULL);
+  query = gst_query_new_caps (filter);
   gst_element_query (priv->src, query);
   gst_query_parse_caps_result (query, &res);
-  g_print ("%s\n", gst_caps_to_string (res));
+  gst_caps_ref (res);
   gst_query_unref (query);
+
+  return res;
 }
 
 static gboolean
@@ -116,7 +121,6 @@ v4l2_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:
@@ -134,8 +138,8 @@ v4l2_set_state (PvSource *source, PvSourceState state)
   return TRUE;
 }
 
-static GVariant *
-v4l2_get_capabilities (PvSource *source, GVariant *props)
+static GBytes *
+v4l2_get_capabilities (PvSource *source, GBytes *filter)
 {
   return NULL;
 }
@@ -149,6 +153,8 @@ on_socket_notify (GObject    *gobject,
   PvV4l2SourcePrivate *priv = source->priv;
   GSocket *socket;
   guint num_handles;
+  GstCaps *caps;
+  GBytes *requested_format;
 
   g_object_get (gobject, "socket", &socket, NULL);
 
@@ -162,6 +168,18 @@ on_socket_notify (GObject    *gobject,
   }
   priv->socket = socket;
 
+  g_object_get (gobject, "requested-format", &requested_format, NULL);
+  g_assert (requested_format != NULL);
+  g_object_set (gobject, "format", requested_format, NULL);
+
+  g_print ("final format %s\n", g_bytes_get_data (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);
+
   g_object_get (priv->sink, "num-handles", &num_handles, NULL);
   if (num_handles == 0) {
     gst_element_set_state (priv->pipeline, GST_STATE_READY);
@@ -171,53 +189,45 @@ on_socket_notify (GObject    *gobject,
 }
 
 static PvSourceOutput *
-v4l2_create_source_output (PvSource *source, GVariant *props, const gchar *prefix)
+v4l2_create_source_output (PvSource    *source,
+                           const gchar *client_path,
+                           GBytes      *format_filter,
+                           const gchar *prefix)
 {
   PvV4l2SourcePrivate *priv = PV_V4L2_SOURCE (source)->priv;
   PvSourceOutput *output;
-  GVariantDict dict;
-  GstCaps *caps;
-  const gchar *str;
-  gint32 i32;
+  GstCaps *caps, *filtered;
+  gchar *str;
 
-  g_variant_dict_init (&dict, props);
-  if (!g_variant_dict_lookup (&dict, "format.encoding", "&s", &str))
-    goto invalid_encoding;
-
-  caps = gst_caps_new_empty_simple (str);
-
-  if (g_variant_dict_lookup (&dict, "format.format", "&s", &str))
-    gst_caps_set_simple (caps, "format", G_TYPE_STRING, str, NULL);
-  if (g_variant_dict_lookup (&dict, "format.width", "i", &i32))
-    gst_caps_set_simple (caps, "width", G_TYPE_INT, (gint) i32, NULL);
-  if (g_variant_dict_lookup (&dict, "format.height", "i", &i32))
-    gst_caps_set_simple (caps, "height", G_TYPE_INT, (gint) i32, NULL);
-  if (g_variant_dict_lookup (&dict, "format.views", "i", &i32))
-    gst_caps_set_simple (caps, "views", G_TYPE_INT, (gint) i32, NULL);
-  if (g_variant_dict_lookup (&dict, "format.chroma-site", "&s", &str))
-    gst_caps_set_simple (caps, "chroma-site", G_TYPE_STRING, str, NULL);
-  if (g_variant_dict_lookup (&dict, "format.colorimetry", "&s", &str))
-    gst_caps_set_simple (caps, "colorimetry", G_TYPE_STRING, str, NULL);
-  if (g_variant_dict_lookup (&dict, "format.interlace-mode", "&s", &str))
-    gst_caps_set_simple (caps, "interlace-mode", G_TYPE_STRING, str, NULL);
-
-  g_print ("caps %s\n", gst_caps_to_string (caps));
-
-  g_object_set (priv->filter, "caps", caps, NULL);
-  gst_caps_unref (caps);
-
-  output = PV_SOURCE_CLASS (pv_v4l2_source_parent_class)->create_source_output (source, props, prefix);
+  str = (gchar *) g_bytes_get_data (format_filter, NULL);
+  g_print ("input filter %s\n", str);
+  caps = gst_caps_from_string (str);
+  if (caps == NULL)
+    goto invalid_caps;
 
   gst_element_set_state (priv->pipeline, GST_STATE_READY);
 
+  filtered = collect_caps (source, caps);
+  if (filtered == NULL || gst_caps_is_empty (filtered))
+    goto no_format;
+
+  str = gst_caps_to_string (filtered);
+  g_print ("output filter %s\n", str);
+  format_filter = g_bytes_new_take (str, strlen (str) + 1);
+
+  output = PV_SOURCE_CLASS (pv_v4l2_source_parent_class)->create_source_output (source, client_path, format_filter, prefix);
+
   g_signal_connect (output, "notify::socket", (GCallback) on_socket_notify, source);
 
   return output;
 
   /* ERRORS */
-invalid_encoding:
+invalid_caps:
+  {
+    return NULL;
+  }
+no_format:
   {
-    g_variant_dict_clear (&dict);
     return NULL;
   }
 }