1 files changed, 25 insertions, 5 deletions

diff --git a/gst/legacyresample/gstlegacyresample.c b/gst/legacyresample/gstlegacyresample.c
index 908b6ad9..cbcd6fdd 100644
--- a/gst/legacyresample/gstlegacyresample.c
+++ b/gst/legacyresample/gstlegacyresample.c
@@ -265,14 +265,34 @@ static GstCaps *
 legacyresample_transform_caps (GstBaseTransform * base,
     GstPadDirection direction, GstCaps * caps)
 {
+  const GValue *val;
+  GstStructure *s;
   GstCaps *res;
-  GstStructure *structure;
 
-  /* transform caps gives one single caps so we can just replace
-   * the rate property with our range. */
+  /* transform single caps into input_caps + input_caps with the rate
+   * field set to our supported range. This ensures that upstream knows
+   * about downstream's prefered rate(s) and can negotiate accordingly. */
   res = gst_caps_copy (caps);
-  structure = gst_caps_get_structure (res, 0);
-  gst_structure_set (structure, "rate", GST_TYPE_INT_RANGE, 1, G_MAXINT, NULL);
+
+  /* first, however, check if the caps contain a range for the rate field, in
+   * which case that side isn't going to care much about the exact sample rate
+   * chosen and we should just assume things will get fixated to something sane
+   * and we may just as well offer our full range instead of the range in the
+   * caps. If the rate is not an int range value, it's likely to express a
+   * real preference or limitation and we should maintain that structure as
+   * preference by putting it first into the transformed caps, and only add
+   * our full rate range as second option  */
+  s = gst_caps_get_structure (res, 0);
+  val = gst_structure_get_value (s, "rate");
+  if (val == NULL || GST_VALUE_HOLDS_INT_RANGE (val)) {
+    /* overwrite existing range, or add field if it doesn't exist yet */
+    gst_structure_set (s, "rate", GST_TYPE_INT_RANGE, 1, G_MAXINT, NULL);
+  } else {
+    /* append caps with full range to existing caps with non-range rate field */
+    s = gst_structure_copy (s);
+    gst_structure_set (s, "rate", GST_TYPE_INT_RANGE, 1, G_MAXINT, NULL);
+    gst_caps_append_structure (res, s);
+  }
 
   return res;
 }