rv20 mv prediction in b frames fix

Originally committed as revision 2712 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/rv10.c

@@ -547,6 +547,10 @@ static int rv10_decode_packet(AVCodecContext *avctx,
             return -1;
     }
 
+    if(s->pict_type == B_TYPE){ //FIXME remove after cleaning mottion_val indexing
+        memset(s->current_picture.motion_val[0], 0, sizeof(int16_t)*2*(s->mb_width*2+2)*(s->mb_height*2+2));
+    }
+
 #ifdef DEBUG
     printf("qscale=%d\n", s->qscale);
 #endif
@@ -575,7 +579,7 @@ static int rv10_decode_packet(AVCodecContext *avctx,
     s->rv10_first_dc_coded[0] = 0;
     s->rv10_first_dc_coded[1] = 0;
     s->rv10_first_dc_coded[2] = 0;
-
+//printf("%d %X %X\n", s->pict_type, s->current_picture.motion_val[0], s->current_picture.motion_val[1]);
     s->block_wrap[0]=
     s->block_wrap[1]=
     s->block_wrap[2]=
@@ -600,7 +604,8 @@ static int rv10_decode_packet(AVCodecContext *avctx,
             av_log(s->avctx, AV_LOG_ERROR, "ERROR at MB %d %d\n", s->mb_x, s->mb_y);
             return -1;
         }
-        ff_h263_update_motion_val(s);
+        if(s->pict_type != B_TYPE)
+            ff_h263_update_motion_val(s);
         MPV_decode_mb(s, s->block);
         if(s->loop_filter)
             ff_h263_loop_filter(s);
@@ -635,7 +640,7 @@ static int rv10_decode_frame(AVCodecContext *avctx,
         *data_size = 0;
         return 0;
     }
-    
+
     if(avctx->slice_count){
         for(i=0; i<avctx->slice_count; i++){
             int offset= avctx->slice_offset[i];