mlpdec: set the channel layout.

Fixes bug 401.
Signed-off-by: Justin Ruggles <justin.ruggles@gmail.com>

CC:libav-stable@libav.org

libavcodec/mlpdec.c

@@ -520,8 +520,10 @@ static int read_restart_header(MLPDecodeContext *m, GetBitContext *gbp,
         cp->huff_lsbs        = 24;
     }
 
-    if (substr == m->max_decoded_substream)
-        m->avctx->channels = s->max_matrix_channel + 1;
+    if (substr == m->max_decoded_substream) {
+        m->avctx->channels       = s->max_matrix_channel + 1;
+        m->avctx->channel_layout = s->ch_layout;
+    }
 
     return 0;
 }