dxva2_vc1: fix signaling of intensity compensation values

lumscale/lumshift don't get reset back to their default values if
intensity compensation is not active, and a wrong signaling here can
cause playback issues.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/dxva2_vc1.c

@@ -38,6 +38,15 @@ static void fill_picture_parameters(AVCodecContext *avctx,
 {
     const MpegEncContext *s = &v->s;
     const Picture *current_picture = s->current_picture_ptr;
+    int intcomp = 0;
+
+    // determine if intensity compensation is needed
+    if (s->pict_type == AV_PICTURE_TYPE_P) {
+      if ((v->fcm == ILACE_FRAME && v->intcomp) || (v->fcm != ILACE_FRAME && v->mv_mode == MV_PMODE_INTENSITY_COMP)) {
+        if (v->lumscale != 32 || v->lumshift != 0 || (s->picture_structure != PICT_FRAME && (v->lumscale2 != 32 && v->lumshift2 != 0)))
+          intcomp = 1;
+      }
+    }
 
     memset(pp, 0, sizeof(*pp));
     pp->wDecodedPictureIndex    =
@@ -74,7 +83,7 @@ static void fill_picture_parameters(AVCodecContext *avctx,
     pp->bBidirectionalAveragingMode = (1                                           << 7) |
                                       ((ctx->cfg->ConfigIntraResidUnsigned != 0)   << 6) |
                                       ((ctx->cfg->ConfigResidDiffAccelerator != 0) << 5) |
-                                      ((v->lumscale != 32 || v->lumshift != 0)     << 4) |
+                                      (intcomp                                     << 4) |
                                       ((v->profile == PROFILE_ADVANCED)            << 3);
     pp->bMVprecisionAndChromaRelation = ((v->mv_mode == MV_PMODE_1MV_HPEL_BILIN) << 3) |
                                         (1                                       << 2) |
@@ -125,12 +134,22 @@ static void fill_picture_parameters(AVCodecContext *avctx,
     pp->bMV_RPS                 = (v->fcm == ILACE_FIELD && pp->bPicBackwardPrediction) ? v->refdist + 9 : 0;
     pp->bReservedBits           = v->pq;
     if (s->picture_structure == PICT_FRAME) {
-        pp->wBitstreamFcodes        = v->lumscale;
-        pp->wBitstreamPCEelements   = v->lumshift;
+        if (intcomp) {
+            pp->wBitstreamFcodes      = v->lumscale;
+            pp->wBitstreamPCEelements = v->lumshift;
+        } else {
+            pp->wBitstreamFcodes      = 32;
+            pp->wBitstreamPCEelements = 0;
+        }
     } else {
         /* Syntax: (top_field_param << 8) | bottom_field_param */
-        pp->wBitstreamFcodes        = (v->lumscale << 8) | v->lumscale;
-        pp->wBitstreamPCEelements   = (v->lumshift << 8) | v->lumshift;
+        if (intcomp) {
+            pp->wBitstreamFcodes      = (v->lumscale << 8) | v->lumscale2;
+            pp->wBitstreamPCEelements = (v->lumshift << 8) | v->lumshift2;
+        } else {
+            pp->wBitstreamFcodes      = (32 << 8) | 32;
+            pp->wBitstreamPCEelements = 0;
+        }
     }
     pp->bBitstreamConcealmentNeed   = 0;
     pp->bBitstreamConcealmentMethod = 0;