sdp: Add new sdpsrc element

This can read from an SDP file or get the SDP data via property. Works
around the problem that sdpdemux inside decodebin fails because the
GST_STATE_CHANGE_NO_PREROLL is not observed by the pipeline.

See https://bugzilla.gnome.org/show_bug.cgi?id=702495

https://bugzilla.gnome.org/show_bug.cgi?id=762860

gst/sdp/Makefile.am

@@ -1,12 +1,13 @@
 plugin_LTLIBRARIES = libgstsdpelem.la
 
-libgstsdpelem_la_SOURCES = gstsdpelem.c gstsdpdemux.h gstsdpdemux.c
+libgstsdpelem_la_SOURCES = gstsdpelem.c gstsdpsrc.c gstsdpdemux.c
 
 libgstsdpelem_la_CFLAGS = $(GST_PLUGINS_BASE_CFLAGS) $(GST_CFLAGS) $(GIO_CFLAGS)
 libgstsdpelem_la_LIBADD = $(GST_PLUGINS_BASE_LIBS) $(GST_BASE_LIBS) $(GIO_LIBS) \
 		       -lgstrtp-@GST_API_VERSION@ -lgstsdp-@GST_API_VERSION@ \
+		       -lgstapp-@GST_API_VERSION@ \
 		       $(GST_LIBS) $(WINSOCK2_LIBS)
 libgstsdpelem_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS)
 libgstsdpelem_la_LIBTOOLFLAGS = $(GST_PLUGIN_LIBTOOLFLAGS)
 
-noinst_HEADERS = gstsdpdemux.h
+noinst_HEADERS = gstsdpdemux.h gstsdpsrc.h

gst/sdp/gstsdpelem.c

@@ -22,6 +22,7 @@
 #endif
 
 #include "gstsdpdemux.h"
+#include "gstsdpsrc.h"
 
 static gboolean
 plugin_init (GstPlugin * plugin)
@@ -29,6 +30,8 @@ plugin_init (GstPlugin * plugin)
   if (!gst_element_register (plugin, "sdpdemux", GST_RANK_NONE,
           GST_TYPE_SDP_DEMUX))
     return FALSE;
+  if (!gst_element_register (plugin, "sdpsrc", GST_RANK_NONE, GST_TYPE_SDP_SRC))
+    return FALSE;
 
   return TRUE;
 }

gst/sdp/gstsdpsrc.c

@@ -0,0 +1,332 @@
+/*
+ * Copyright (C) 2016 Sebastian Dröge <sebastian@centricular.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.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "gstsdpsrc.h"
+#include <gst/app/app.h>
+#include <string.h>
+
+GST_DEBUG_CATEGORY_STATIC (sdp_src_debug);
+#define GST_CAT_DEFAULT sdp_src_debug
+
+static GstStaticPadTemplate src_template = GST_STATIC_PAD_TEMPLATE ("stream_%u",
+    GST_PAD_SRC,
+    GST_PAD_SOMETIMES,
+    GST_STATIC_CAPS ("application/x-rtp"));
+
+enum
+{
+  PROP_0,
+  PROP_LOCATION,
+  PROP_SDP
+};
+
+static void gst_sdp_src_handler_init (gpointer g_iface, gpointer iface_data);
+
+#define gst_sdp_src_parent_class parent_class
+G_DEFINE_TYPE_WITH_CODE (GstSdpSrc, gst_sdp_src, GST_TYPE_BIN,
+    G_IMPLEMENT_INTERFACE (GST_TYPE_URI_HANDLER, gst_sdp_src_handler_init));
+
+static void
+gst_sdp_src_finalize (GObject * object)
+{
+  GstSdpSrc *self = GST_SDP_SRC_CAST (object);
+
+  if (self->sdp_buffer)
+    gst_buffer_unref (self->sdp_buffer);
+  g_free (self->location);
+  g_free (self->sdp);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gst_sdp_src_get_property (GObject * object, guint prop_id,
+    GValue * value, GParamSpec * pspec)
+{
+  GstSdpSrc *self = GST_SDP_SRC_CAST (object);
+
+  switch (prop_id) {
+    case PROP_LOCATION:
+      g_value_set_string (value, self->location);
+      break;
+    case PROP_SDP:
+      g_value_set_string (value, self->sdp);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+static void
+gst_sdp_src_set_property (GObject * object, guint prop_id,
+    const GValue * value, GParamSpec * pspec)
+{
+  GstSdpSrc *self = GST_SDP_SRC_CAST (object);
+
+  switch (prop_id) {
+    case PROP_LOCATION:
+      g_free (self->location);
+      self->location = g_value_dup_string (value);
+      break;
+    case PROP_SDP:
+      g_free (self->sdp);
+      self->sdp = g_value_dup_string (value);
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+static void
+pad_added_cb (GstElement * element, GstPad * pad, gpointer user_data)
+{
+  GstSdpSrc *self = GST_SDP_SRC_CAST (user_data);
+  GstPad *ghost;
+
+  ghost =
+      gst_ghost_pad_new_from_template (GST_PAD_NAME (pad), pad,
+      gst_static_pad_template_get (&src_template));
+  gst_pad_set_active (ghost, TRUE);
+  gst_element_add_pad (GST_ELEMENT_CAST (self), ghost);
+}
+
+static void
+pad_removed_cb (GstElement * element, GstPad * pad, gpointer user_data)
+{
+  GstSdpSrc *self = GST_SDP_SRC_CAST (user_data);
+  GstPad *peer;
+
+  peer = gst_pad_get_peer (pad);
+  if (peer) {
+    GstPad *ghost =
+        GST_PAD_CAST (gst_proxy_pad_get_internal (GST_PROXY_PAD (peer)));
+
+    if (ghost) {
+      gst_ghost_pad_set_target (GST_GHOST_PAD_CAST (ghost), NULL);
+      gst_element_remove_pad (GST_ELEMENT_CAST (self), ghost);
+      gst_object_unref (ghost);
+    }
+
+    gst_object_unref (peer);
+  }
+}
+
+static void
+no_more_pads_cb (GstElement * element, gpointer user_data)
+{
+  gst_element_no_more_pads (GST_ELEMENT_CAST (user_data));
+}
+
+static void
+remove_pad (const GValue * item, gpointer user_data)
+{
+  GstElement *self = user_data;
+  GstPad *pad = g_value_get_object (item);
+
+  gst_element_remove_pad (self, pad);
+}
+
+static GstStateChangeReturn
+gst_sdp_src_change_state (GstElement * element, GstStateChange transition)
+{
+  GstSdpSrc *self = GST_SDP_SRC_CAST (element);
+  GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
+
+  switch (transition) {
+    case GST_STATE_CHANGE_NULL_TO_READY:
+      GST_OBJECT_LOCK (self);
+      if (self->sdp_buffer)
+        gst_buffer_unref (self->sdp_buffer);
+      self->sdp_buffer = NULL;
+
+      if (self->location && strcmp (self->location, "sdp://") != 0) {
+        /* Do nothing */
+      } else if (self->sdp) {
+        self->sdp_buffer =
+            gst_buffer_new_wrapped (self->sdp, strlen (self->sdp) + 1);
+      } else {
+        ret = GST_STATE_CHANGE_FAILURE;
+      }
+      GST_OBJECT_UNLOCK (self);
+
+      if (ret != GST_STATE_CHANGE_FAILURE) {
+        if (self->sdp_buffer) {
+          GstCaps *caps = gst_caps_new_empty_simple ("application/sdp");
+
+          self->src = gst_element_factory_make ("appsrc", NULL);
+          g_object_set (self->src, "caps", caps, "emit-signals", FALSE, NULL);
+          gst_caps_unref (caps);
+        } else {
+          self->src = gst_element_factory_make ("filesrc", NULL);
+          g_object_set (self->src, "location", self->location + 6, NULL);
+        }
+
+        self->demux = gst_element_factory_make ("sdpdemux", NULL);
+        g_signal_connect (self->demux, "pad-added", G_CALLBACK (pad_added_cb),
+            self);
+        g_signal_connect (self->demux, "pad-removed",
+            G_CALLBACK (pad_removed_cb), self);
+        g_signal_connect (self->demux, "no-more-pads",
+            G_CALLBACK (no_more_pads_cb), self);
+        gst_bin_add_many (GST_BIN_CAST (self), self->src, self->demux, NULL);
+        gst_element_link_pads (self->src, "src", self->demux, "sink");
+      }
+      break;
+    default:
+      break;
+  }
+
+  if (ret == GST_STATE_CHANGE_FAILURE)
+    return ret;
+  ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
+  if (ret == GST_STATE_CHANGE_FAILURE)
+    return ret;
+
+  switch (transition) {
+    case GST_STATE_CHANGE_READY_TO_NULL:{
+      GstIterator *it;
+
+      it = gst_element_iterate_src_pads (GST_ELEMENT_CAST (self));
+      while (gst_iterator_foreach (it, remove_pad, self) == GST_ITERATOR_RESYNC)
+        gst_iterator_resync (it);
+      gst_iterator_free (it);
+
+      if (self->src) {
+        gst_bin_remove (GST_BIN_CAST (self), self->src);
+        self->src = NULL;
+      }
+      if (self->demux) {
+        gst_bin_remove (GST_BIN_CAST (self), self->demux);
+        self->demux = NULL;
+      }
+      break;
+    }
+    case GST_STATE_CHANGE_READY_TO_PAUSED:
+      if (ret != GST_STATE_CHANGE_FAILURE)
+        ret = GST_STATE_CHANGE_NO_PREROLL;
+      if (self->sdp_buffer) {
+        if (gst_app_src_push_buffer (GST_APP_SRC_CAST (self->src),
+                gst_buffer_ref (self->sdp_buffer)) != GST_FLOW_OK)
+          ret = GST_STATE_CHANGE_FAILURE;
+        else
+          gst_app_src_end_of_stream (GST_APP_SRC_CAST (self->src));
+      }
+      break;
+    default:
+      break;
+  }
+
+  return ret;
+}
+
+static void
+gst_sdp_src_class_init (GstSdpSrcClass * klass)
+{
+  GObjectClass *gobject_class = (GObjectClass *) klass;
+  GstElementClass *element_class = (GstElementClass *) klass;
+
+  GST_DEBUG_CATEGORY_INIT (sdp_src_debug, "sdpsrc", 0, "SDP Source");
+
+  gobject_class->finalize = gst_sdp_src_finalize;
+  gobject_class->set_property = gst_sdp_src_set_property;
+  gobject_class->get_property = gst_sdp_src_get_property;
+
+  g_object_class_install_property (gobject_class, PROP_LOCATION,
+      g_param_spec_string ("location",
+          "Location",
+          "URI to SDP file (sdp:///path/to/file)", NULL,
+          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
+  g_object_class_install_property (gobject_class, PROP_SDP,
+      g_param_spec_string ("sdp",
+          "SDP",
+          "SDP description used instead of location", NULL,
+          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
+  gst_element_class_add_pad_template (element_class,
+      gst_static_pad_template_get (&src_template));
+
+  gst_element_class_set_static_metadata (element_class, "SDP Source",
+      "Source/Network/RTP",
+      "Stream RTP based on an SDP",
+      "Sebastian Dröge <sebastian@centricular.com>");
+
+  element_class->change_state = GST_DEBUG_FUNCPTR (gst_sdp_src_change_state);
+}
+
+static void
+gst_sdp_src_init (GstSdpSrc * self)
+{
+}
+
+static GstURIType
+gst_sdp_src_get_uri_type (GType type)
+{
+  return GST_URI_SRC;
+}
+
+static const gchar *const *
+gst_sdp_src_get_protocols (GType type)
+{
+  static const gchar *protocols[] = { "sdp", 0 };
+
+  return protocols;
+}
+
+static gchar *
+gst_sdp_src_get_uri (GstURIHandler * handler)
+{
+  gchar *uri = NULL;
+
+  g_object_get (handler, "location", &uri, NULL);
+
+  return uri;
+}
+
+static gboolean
+gst_sdp_src_set_uri (GstURIHandler * handler, const gchar * uri,
+    GError ** error)
+{
+  if (uri && !g_str_has_prefix (uri, "sdp://")) {
+    g_set_error (error, GST_URI_ERROR, GST_URI_ERROR_BAD_URI,
+        "Invalid SDP URI");
+    return FALSE;
+  }
+
+  g_object_set (handler, "location", uri, NULL);
+
+  return TRUE;
+}
+
+static void
+gst_sdp_src_handler_init (gpointer g_iface, gpointer iface_data)
+{
+  GstURIHandlerInterface *iface = (GstURIHandlerInterface *) g_iface;
+
+  iface->get_type = gst_sdp_src_get_uri_type;
+  iface->get_protocols = gst_sdp_src_get_protocols;
+  iface->get_uri = gst_sdp_src_get_uri;
+  iface->set_uri = gst_sdp_src_set_uri;
+}

gst/sdp/gstsdpsrc.h

@@ -0,0 +1,62 @@
+/* GStreamer
+ * Copyright (C) 2016 Sebastian Dröge <sebastian@centricular.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.
+ */
+
+#ifndef __GST_SDP_SRC_H__
+#define __GST_SDP_SRC_H__
+
+#include <gst/gst.h>
+
+G_BEGIN_DECLS
+#define GST_TYPE_SDP_SRC \
+  (gst_sdp_src_get_type())
+#define GST_SDP_SRC(obj) \
+  (G_TYPE_CHECK_INSTANCE_CAST ((obj), GST_TYPE_SDP_SRC, GstSdpSrc))
+#define GST_SDP_SRC_CAST(obj) \
+  ((GstSdpSrc *) obj)
+#define GST_SDP_SRC_CLASS(klass) \
+  (G_TYPE_CHECK_CLASS_CAST ((klass), GST_TYPE_SDP_SRC, GstSdpSrcClass))
+#define GST_IS_SDP_SRC(obj) \
+  (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GST_TYPE_SDP_SRC))
+#define GST_IS_SDP_SRC_CLASS(klass) \
+  (G_TYPE_CHECK_CLASS_TYPE ((klass), GST_TYPE_SDP_SRC))
+
+typedef struct _GstSdpSrc GstSdpSrc;
+typedef struct _GstSdpSrcClass GstSdpSrcClass;
+
+struct _GstSdpSrc
+{
+  GstBin parent;
+
+  gchar *location;
+  gchar *sdp;
+
+  GstBuffer *sdp_buffer;
+  GstElement *src;
+  GstElement *demux;
+};
+
+struct _GstSdpSrcClass
+{
+  GstBinClass parent;
+};
+
+GType gst_sdp_src_get_type (void);
+
+G_END_DECLS
+#endif /* __GST_SDP_SRC_H__ */