v4l2src: Ensure all caps a fixated

The code relied on the list compare function to fixate the caps
but if the caps only has one structure, the compare function will
never get called. Capture device for which there is only one
structure in the caps would then get some assertion and later
fail badly.

Instead, fixate before inserting into the list and split the reading
and the fixation of the structures.

1 files changed, 28 insertions, 24 deletions

diff --git a/sys/v4l2/gstv4l2src.c b/sys/v4l2/gstv4l2src.c
index e98cb7985..9ed87849c 100644
--- a/sys/v4l2/gstv4l2src.c
+++ b/sys/v4l2/gstv4l2src.c
@@ -277,46 +277,47 @@ gst_vl42_src_fixate_fields (GQuark field_id, GValue * value, gpointer user_data)
 
 static void
 gst_v4l2_src_fixate_struct_with_preference (GstStructure * s,
-    struct PreferedCapsInfo *pref, gint * width, gint * height,
-    gint * fps_n, gint * fps_d)
+    struct PreferedCapsInfo *pref)
 {
-  if (gst_structure_has_field (s, "width")) {
+  if (gst_structure_has_field (s, "width"))
     gst_structure_fixate_field_nearest_int (s, "width", pref->width);
 
-    if (width)
-      gst_structure_get_int (s, "width", width);
-  }
-
-  if (gst_structure_has_field (s, "height")) {
+  if (gst_structure_has_field (s, "height"))
     gst_structure_fixate_field_nearest_int (s, "height", pref->height);
 
-    if (height)
-      gst_structure_get_int (s, "height", height);
-  }
-
-  if (gst_structure_has_field (s, "framerate")) {
+  if (gst_structure_has_field (s, "framerate"))
     gst_structure_fixate_field_nearest_fraction (s, "framerate", pref->fps_n,
         pref->fps_d);
 
-    if (fps_n && fps_d)
-      gst_structure_get_fraction (s, "framerate", fps_n, fps_d);
-  }
-
   /* Finally, fixate everything else except the interlace-mode and colorimetry
    * which still need further negotiation as it wasn't probed */
   gst_structure_map_in_place (s, gst_vl42_src_fixate_fields, s);
 }
 
+static void
+gst_v4l2_src_parse_fixed_struct (GstStructure * s,
+    gint * width, gint * height, gint * fps_n, gint * fps_d)
+{
+  if (gst_structure_has_field (s, "width") && width)
+    gst_structure_get_int (s, "width", width);
+
+  if (gst_structure_has_field (s, "height") && height)
+    gst_structure_get_int (s, "height", height);
+
+  if (gst_structure_has_field (s, "framerate") && fps_n && fps_d)
+    gst_structure_get_fraction (s, "framerate", fps_n, fps_d);
+}
+
 /* TODO Consider framerate */
 static gint
-gst_v4l2src_caps_fixate_and_compare (GstStructure * a, GstStructure * b,
+gst_v4l2src_fixed_caps_compare (GstStructure * a, GstStructure * b,
     struct PreferedCapsInfo *pref)
 {
   gint aw = G_MAXINT, ah = G_MAXINT, ad = G_MAXINT;
   gint bw = G_MAXINT, bh = G_MAXINT, bd = G_MAXINT;
 
-  gst_v4l2_src_fixate_struct_with_preference (a, pref, &aw, &ah, NULL, NULL);
-  gst_v4l2_src_fixate_struct_with_preference (b, pref, &bw, &bh, NULL, NULL);
+  gst_v4l2_src_parse_fixed_struct (a, &aw, &ah, NULL, NULL);
+  gst_v4l2_src_parse_fixed_struct (b, &bw, &bh, NULL, NULL);
 
   /* When both are smaller then pref, just append to the end */
   if ((bw < pref->width || bh < pref->height)
@@ -380,16 +381,19 @@ gst_v4l2src_fixate (GstBaseSrc * basesrc, GstCaps * caps, GstStructure * pref_s)
    * transformation to happen downstream. */
   if (pref_s) {
     pref_s = gst_structure_copy (pref_s);
-    gst_v4l2_src_fixate_struct_with_preference (pref_s, &pref, &pref.width,
-        &pref.height, &pref.fps_n, &pref.fps_d);
+    gst_v4l2_src_fixate_struct_with_preference (pref_s, &pref);
+    gst_v4l2_src_parse_fixed_struct (pref_s, &pref.width, &pref.height,
+        &pref.fps_n, &pref.fps_d);
     gst_structure_free (pref_s);
   }
 
   /* Sort the structures to get the caps that is nearest to our preferences,
    * first */
-  while ((s = gst_caps_steal_structure (caps, 0)))
+  while ((s = gst_caps_steal_structure (caps, 0))) {
+    gst_v4l2_src_fixate_struct_with_preference (s, &pref);
     caps_list = g_list_insert_sorted_with_data (caps_list, s,
-        (GCompareDataFunc) gst_v4l2src_caps_fixate_and_compare, &pref);
+        (GCompareDataFunc) gst_v4l2src_fixed_caps_compare, &pref);
+  }
 
   while (caps_list) {
     s = caps_list->data;