audioresample: Optimize transform_caps()

If the second and next caps structures are a subset of the already existing
transformed caps we can safely skip them because we would transform them to
the same caps again.

diff --git a/gst/audioresample/gstaudioresample.c b/gst/audioresample/gstaudioresample.c
index 1d0462f..7bf3980 100644 (file)
--- a/gst/audioresample/gstaudioresample.c
+++ b/gst/audioresample/gstaudioresample.c
@@ -293,10 +293,16 @@ gst_audio_resample_transform_caps (GstBaseTransform * base,
   /* 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);
-
-  n = gst_caps_get_size (res);
+  res = gst_caps_new_empty ();
+  n = gst_caps_get_size (caps);
   for (i = 0; i < n; i++) {
+    s = gst_caps_get_structure (caps, i);
+
+    /* If this is already expressed by the existing caps
+     * skip this structure */
+    if (i > 0 && gst_caps_is_subset_structure (res, s))
+      continue;
+
     /* 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
@@ -305,17 +311,17 @@ gst_audio_resample_transform_caps (GstBaseTransform * base,
      * 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, i);
+    s = gst_structure_copy (s);
     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_caps_append_structure (res, gst_structure_copy (s));
       gst_structure_set (s, "rate", GST_TYPE_INT_RANGE, 1, G_MAXINT, NULL);
-      gst_caps_merge_structure (res, s);
     }
+    gst_caps_append_structure (res, s);
   }
 
   if (filter) {