encodebasebin: Fix parser selection

If an encoder supports multiple codecs (a bin wrapping/auto-plugging encoders)
then its src pad template caps might list the supported codecs. Without this
patch the selected parser would be the one corresponding to the first codec,
leading to caps negotiation error later on. The proposed fix is to check the
media type on the parser candidates sink pad templates according to the
requested encoded format.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7756>

diff --git a/subprojects/gst-plugins-base/gst/encoding/gstencodebasebin.c b/subprojects/gst-plugins-base/gst/encoding/gstencodebasebin.c
index 1d64d4d34c3a464b05ffa6c2fd0f8758ece8d053..488a26dd173527d69d123a79f14850a3f61aaa0f 100644 (file)
--- a/subprojects/gst-plugins-base/gst/encoding/gstencodebasebin.c
+++ b/subprojects/gst-plugins-base/gst/encoding/gstencodebasebin.c
@@ -831,8 +831,18 @@ _create_compatible_processor (GList * all_processors,
 {
   GList *processors1, *processors, *tmp;
   GstElement *processor = NULL;
-  GstElementFactory *factory = NULL;
   GstCaps *format = NULL;
+  GstCaps *encoding_format = NULL;
+  GstStructure *s;
+  const gchar *encoding_media_type;
+
+  encoding_format = gst_encoding_profile_get_format (sprof);
+  if (G_UNLIKELY (gst_caps_is_empty (encoding_format))) {
+    return NULL;
+  }
+
+  s = gst_caps_get_structure (encoding_format, 0);
+  encoding_media_type = gst_structure_get_name (s);
 
   if (encoder) {
     GstPadTemplate *template = gst_element_get_pad_template (encoder, "src");
@@ -843,7 +853,7 @@ _create_compatible_processor (GList * all_processors,
 
   if (!format || gst_caps_is_any (format)) {
     gst_clear_caps (&format);
-    format = gst_encoding_profile_get_format (sprof);
+    format = gst_caps_ref (encoding_format);
   }
 
   GST_DEBUG ("Getting list of processors for format %" GST_PTR_FORMAT, format);
@@ -864,20 +874,42 @@ _create_compatible_processor (GList * all_processors,
   }
 
   for (tmp = processors; tmp; tmp = tmp->next) {
-    /* FIXME : We're only picking the first one so far */
-    /* FIXME : signal the user if he wants this */
-    factory = (GstElementFactory *) tmp->data;
+    GstElementFactory *candidate_factory = GST_ELEMENT_FACTORY_CAST (tmp->data);
+    GstPadTemplate *tmpl;
+    GstCaps *processor_caps;
+    gboolean is_compatible = FALSE;
+
+    processor = gst_element_factory_create (candidate_factory, NULL);
+    tmpl = gst_element_get_pad_template (processor, "sink");
+    processor_caps = gst_pad_template_get_caps (tmpl);
+
+    if (gst_caps_is_any (processor_caps)) {
+      is_compatible = TRUE;
+    } else if (!gst_caps_is_empty (processor_caps)) {
+      GstStructure *structure = gst_caps_get_structure (processor_caps, 0);
+      if (!strcmp (encoding_media_type, gst_structure_get_name (structure))) {
+        is_compatible = TRUE;
+      }
+    }
+
+    gst_clear_caps (&processor_caps);
+
+    if (!is_compatible) {
+      GST_DEBUG ("Processor %" GST_PTR_FORMAT " is not compatible with format %"
+          GST_PTR_FORMAT, processor, encoding_format);
+      gst_clear_object (&processor);
+      continue;
+    }
+
+    /* FIXME : signal the user if he wants this parser */
     break;
   }
 
-  if (factory)
-    processor = gst_element_factory_create (factory, NULL);
-
   gst_plugin_feature_list_free (processors);
 
 beach:
-  if (format)
-    gst_caps_unref (format);
+  gst_clear_caps (&format);
+  gst_clear_caps (&encoding_format);
 
   return processor;
 }