Merge commit 'c8cf461c19e8e35df4b7364d9b90aa42f1ab4560'

* commit 'c8cf461c19e8e35df4b7364d9b90aa42f1ab4560':
  dcadec: Do not decode the XCh extension when downmixing to stereo

Conflicts:
	libavcodec/dcadec.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/dcadec.c

@@ -2329,6 +2329,17 @@ static int dca_decode_frame(AVCodecContext *avctx, void *data,
     { /* xxx should also do MA extensions */
         if (s->amode < 16) {
             avctx->channel_layout = dca_core_channel_layout[s->amode];
+
+            if (s->prim_channels + !!s->lfe > 2 &&
+                avctx->request_channel_layout == AV_CH_LAYOUT_STEREO) {
+                /*
+                 * Neither the core's auxiliary data nor our default tables contain
+                 * downmix coefficients for the additional channel coded in the XCh
+                 * extension, so when we're doing a Stereo downmix, don't decode it.
+                 */
+                s->xch_disable = 1;
+            }
+
 #if FF_API_REQUEST_CHANNELS
 FF_DISABLE_DEPRECATION_WARNINGS
             if (s->xch_present && !s->xch_disable &&