sdpdemux: add "media" property to allow audio-only or video-only streaming

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3531>

subprojects/gst-plugins-bad/docs/plugins/gst_plugins_cache.json

@@ -229367,6 +229367,18 @@
                         "type": "guint",
                         "writable": true
                     },
+                    "media": {
+                        "blurb": "Media to use, e.g. audio or video (NULL = all)",
+                        "conditionally-available": false,
+                        "construct": false,
+                        "construct-only": false,
+                        "controllable": false,
+                        "default": "NULL",
+                        "mutable": "null",
+                        "readable": true,
+                        "type": "gchararray",
+                        "writable": true
+                    },
                     "redirect": {
                         "blurb": "Sends a redirection message instead of using a custom session element",
                         "conditionally-available": false,

subprojects/gst-plugins-bad/gst/sdp/gstsdpdemux.c

@@ -190,6 +190,18 @@ gst_sdp_demux_class_init (GstSDPDemuxClass * klass)
           DEFAULT_RTCP_MODE,
           G_PARAM_READWRITE | G_PARAM_CONSTRUCT | G_PARAM_STATIC_STRINGS));
 
+  /**
+   * GstSDPDemux:media:
+   *
+   * Media to use, e.g. audio or video (NULL=allow all).
+   *
+   * Since: 1.24
+   */
+  g_object_class_install_property (gobject_class, PROP_MEDIA,
+      g_param_spec_string ("media", "Media",
+          "Media to use, e.g. audio or video (NULL = all)", DEFAULT_MEDIA,
+          G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
   gst_element_class_add_static_pad_template (gstelement_class, &sinktemplate);
   gst_element_class_add_static_pad_template (gstelement_class, &rtptemplate);
 
@@ -266,6 +278,12 @@ gst_sdp_demux_set_property (GObject * object, guint prop_id,
     case PROP_RTCP_MODE:
       demux->rtcp_mode = g_value_get_enum (value);
       break;
+    case PROP_MEDIA:
+      GST_OBJECT_LOCK (demux);
+      /* g_intern_string() is NULL-safe */
+      demux->media = g_intern_string (g_value_get_string (value));
+      GST_OBJECT_UNLOCK (demux);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -296,6 +314,11 @@ gst_sdp_demux_get_property (GObject * object, guint prop_id, GValue * value,
     case PROP_RTCP_MODE:
       g_value_set_enum (value, demux->rtcp_mode);
       break;
+    case PROP_MEDIA:
+      GST_OBJECT_LOCK (demux);
+      g_value_set_string (value, demux->media);
+      GST_OBJECT_UNLOCK (demux);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -436,6 +459,7 @@ static GstSDPStream *
 gst_sdp_demux_create_stream (GstSDPDemux * demux, GstSDPMessage * sdp, gint idx)
 {
   GstSDPStream *stream;
+  const gchar *media_filter;
   const gchar *payload;
   const GstSDPMedia *media;
   const GstSDPConnection *conn;
@@ -445,6 +469,16 @@ gst_sdp_demux_create_stream (GstSDPDemux * demux, GstSDPMessage * sdp, gint idx)
   if (media == NULL)
     return NULL;
 
+  GST_OBJECT_LOCK (demux);
+  media_filter = demux->media;
+  GST_OBJECT_UNLOCK (demux);
+
+  if (media_filter != NULL && !g_str_equal (media_filter, media->media)) {
+    GST_INFO_OBJECT (demux, "Skipping media %s (filter: %s)", media->media,
+        media_filter);
+    return NULL;
+  }
+
   stream = g_new0 (GstSDPStream, 1);
   stream->parent = demux;
   /* we mark the pad as not linked, we will mark it as OK when we add the pad to

subprojects/gst-plugins-bad/gst/sdp/gstsdpdemux.h

@@ -118,6 +118,7 @@ struct _GstSDPDemux {
   guint64           udp_timeout;
   guint             latency;
   gboolean          redirect;
+  const gchar      *media; /* if non-NULL only hook up these kinds of media (video/audio) */ /* interned string */
   GstSDPDemuxRTCPMode rtcp_mode;
 
   /* session management */