typefinding: improve wavpack typefinder

Check for second block sync and return different
probabilities depending on what we found (trumping
the AAC loas typefinder's LIKELY probability after
finding a second frame sync in this particular case).

https://bugzilla.gnome.org/show_bug.cgi?id=687674

diff --git a/gst/typefind/gsttypefindfunctions.c b/gst/typefind/gsttypefindfunctions.c
index 409cd2f..8b84dca 100644 (file)
--- a/gst/typefind/gsttypefindfunctions.c
+++ b/gst/typefind/gsttypefindfunctions.c
@@ -1678,9 +1678,11 @@ GST_STATIC_CAPS ("audio/x-wavpack-correction, framed = (boolean) false");
 static void
 wavpack_type_find (GstTypeFind * tf, gpointer unused)
 {
+  GstTypeFindProbability base_prob = GST_TYPE_FIND_POSSIBLE;
   guint64 offset;
   guint32 blocksize;
   const guint8 *data;
+  guint count_wv, count_wvc;
 
   data = gst_type_find_peek (tf, 0, 32);
   if (!data)
@@ -1695,6 +1697,8 @@ wavpack_type_find (GstTypeFind * tf, gpointer unused)
    * work in pull-mode */
   blocksize = GST_READ_UINT32_LE (data + 4);
   GST_LOG ("wavpack header, blocksize=0x%04x", blocksize);
+  count_wv = 0;
+  count_wvc = 0;
   offset = 32;
   while (offset < 8 + blocksize) {
     guint32 sublen;
@@ -1720,18 +1724,38 @@ wavpack_type_find (GstTypeFind * tf, gpointer unused)
       switch (data[0] & 0x0f) {
         case 0xa:              /* ID_WV_BITSTREAM  */
         case 0xc:              /* ID_WVX_BITSTREAM */
-          gst_type_find_suggest (tf, GST_TYPE_FIND_LIKELY, WAVPACK_CAPS);
-          return;
+          ++count_wv;
+          break;
         case 0xb:              /* ID_WVC_BITSTREAM */
-          gst_type_find_suggest (tf, GST_TYPE_FIND_LIKELY,
-              WAVPACK_CORRECTION_CAPS);
-          return;
+          ++count_wvc;
+          break;
         default:
           break;
       }
+      if (count_wv >= 5 || count_wvc >= 5)
+        break;
     }
     offset += sublen;
   }
+
+  /* check for second block header */
+  data = gst_type_find_peek (tf, 8 + blocksize, 4);
+  if (data != NULL && memcmp (data, "wvpk", 4) == 0) {
+    GST_DEBUG ("found second block sync");
+    base_prob = GST_TYPE_FIND_LIKELY;
+  }
+
+  GST_DEBUG ("wvc=%d, wv=%d", count_wvc, count_wv);
+
+  if (count_wvc > 0 && count_wvc > count_wv) {
+    gst_type_find_suggest (tf,
+        MIN (base_prob + 5 * count_wvc, GST_TYPE_FIND_NEARLY_CERTAIN),
+        WAVPACK_CORRECTION_CAPS);
+  } else if (count_wv > 0) {
+    gst_type_find_suggest (tf,
+        MIN (base_prob + 5 * count_wv, GST_TYPE_FIND_NEARLY_CERTAIN),
+        WAVPACK_CAPS);
+  }
 }
 
 /*** application/postscrip ***/