avcodec/dpx: check packing

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

libavcodec/dpx.c

@@ -129,6 +129,11 @@ static int decode_frame(AVCodecContext *avctx,
     packing = read16(&buf, endian);
     encoding = read16(&buf, endian);
 
+    if (packing > 1) {
+        avpriv_report_missing_feature(avctx,
+                                      "Unsupported packing %d\n", packing);
+        return AVERROR_PATCHWELCOME;
+    }
     if (encoding) {
         avpriv_report_missing_feature(avctx,
                                       "Unsupported encoding %d\n", encoding);