h264: Workaround invalid flag combinations of 8x8 inference.

Fixes Ticket555
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/h264.c

@@ -2770,6 +2770,10 @@ static int decode_slice_header(H264Context *h, H264Context *h0){
     if(h->sps.frame_mbs_only_flag){
         s->picture_structure= PICT_FRAME;
     }else{
+        if(!h->sps.direct_8x8_inference_flag && slice_type == AV_PICTURE_TYPE_B){
+            av_log(h->s.avctx, AV_LOG_ERROR, "This stream was generated by a broken encoder, invalid 8x8 inference\n");
+            return -1;
+        }
         if(get_bits1(&s->gb)) { //field_pic_flag
             s->picture_structure= PICT_TOP_FIELD + get_bits1(&s->gb); //bottom_field_flag
         } else {

libavcodec/h264_ps.c

@@ -408,10 +408,6 @@ int ff_h264_decode_seq_parameter_set(H264Context *h){
         sps->mb_aff= 0;
 
     sps->direct_8x8_inference_flag= get_bits1(&s->gb);
-    if(!sps->frame_mbs_only_flag && !sps->direct_8x8_inference_flag){
-        av_log(h->s.avctx, AV_LOG_ERROR, "This stream was generated by a broken encoder, invalid 8x8 inference\n");
-        goto fail;
-    }
 
 #ifndef ALLOW_INTERLACE
     if(sps->mb_aff)