v4l2: fix probing and enumeration of stepwise frame sizes

The code enumerating STEPWISE framesizes would start from
(min_w, min_h) and then add (step_w, step_h) to get the
next framesize. However, it should really allow any width
from min_w to max_w with step_w and same for heights.
Secondly, we would add and probe each individual stepped
frame size to the caps as separate structure, which would
lead to hundreds if not thousands of structs ending up in
the probed caps. Use integer ranges with steps instead.

This was particularly noticable with the Raspberry Pi Cam.

https://bugzilla.gnome.org/show_bug.cgi?id=724521
https://bugzilla.gnome.org/show_bug.cgi?id=732458
https://bugzilla.gnome.org/show_bug.cgi?id=726521

diff --git a/sys/v4l2/gstv4l2object.c b/sys/v4l2/gstv4l2object.c
index 61e6989..83598ae 100644 (file)
--- a/sys/v4l2/gstv4l2object.c
+++ b/sys/v4l2/gstv4l2object.c
@@ -1948,6 +1948,8 @@ gst_v4l2_object_probe_caps_for_format (GstV4l2Object * v4l2object,
     GST_DEBUG_OBJECT (v4l2object->element,
         "done iterating discrete frame sizes");
   } else if (size.type == V4L2_FRMSIZE_TYPE_STEPWISE) {
+    guint32 maxw, maxh, step_w, step_h;
+
     GST_DEBUG_OBJECT (v4l2object->element, "we have stepwise frame sizes:");
     GST_DEBUG_OBJECT (v4l2object->element, "min width:   %d",
         size.stepwise.min_width);
@@ -1962,21 +1964,34 @@ gst_v4l2_object_probe_caps_for_format (GstV4l2Object * v4l2object,
     GST_DEBUG_OBJECT (v4l2object->element, "step height: %d",
         size.stepwise.step_height);
 
-    for (w = size.stepwise.min_width, h = size.stepwise.min_height;
-        w <= size.stepwise.max_width && h <= size.stepwise.max_height;
-        w += size.stepwise.step_width, h += size.stepwise.step_height) {
-      if (w == 0 || h == 0)
-        continue;
+    w = MAX (size.stepwise.min_width, 1);
+    h = MAX (size.stepwise.min_height, 1);
+    maxw = MIN (size.stepwise.max_width, G_MAXINT);
+    maxh = MIN (size.stepwise.max_height, G_MAXINT);
+
+    step_w = MAX (size.stepwise.step_width, 1);
+    step_h = MAX (size.stepwise.step_height, 1);
+
+    /* FIXME: check for sanity and that min/max are multiples of the steps */
 
-      tmp =
-          gst_v4l2_object_probe_caps_for_format_and_size (v4l2object,
-          pixelformat, w, h, template);
+    /* we only query details for the max width/height since it's likely the
+     * most restricted if there are any resolution-dependent restrictions */
+    tmp = gst_v4l2_object_probe_caps_for_format_and_size (v4l2object,
+        pixelformat, maxw, maxh, template);
 
-      if (tmp)
-        results = g_list_prepend (results, tmp);
+    if (tmp) {
+      GValue step_range = G_VALUE_INIT;
+
+      g_value_init (&step_range, GST_TYPE_INT_RANGE);
+      gst_value_set_int_range_step (&step_range, w, maxw, step_w);
+      gst_structure_set_value (tmp, "width", &step_range);
+
+      gst_value_set_int_range_step (&step_range, h, maxh, step_h);
+      gst_structure_take_value (tmp, "height", &step_range);
+
+      /* no point using the results list here, since there's only one struct */
+      gst_v4l2_object_update_and_append (v4l2object, pixelformat, ret, tmp);
     }
-    GST_DEBUG_OBJECT (v4l2object->element,
-        "done iterating stepwise frame sizes");
   } else if (size.type == V4L2_FRMSIZE_TYPE_CONTINUOUS) {
     guint32 maxw, maxh;