Merge commit '677c804a'

* commit '677c804a':
  aac: correctly map 7.1ch-wide AAC from FDK AAC encoder

Sample: FDK_7.1ch_wide.aac
Merged-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/aacdec.c

@@ -303,6 +303,11 @@ static uint64_t sniff_channel_order(uint8_t (*layout_map)[3], int tags)
     if (num_back_channels < 0)
         return 0;
 
+    if (num_side_channels == 0 && num_back_channels >= 4) {
+        num_side_channels = 2;
+        num_back_channels -= 2;
+    }
+
     i = 0;
     if (num_front_channels & 1) {
         e2c_vec[i] = (struct elem_to_channel) {