30l: when reading mb_offset in RV30 slice header its size

should be calculated from current frame dimensions

Originally committed as revision 16536 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/rv30.c

@@ -51,13 +51,12 @@ static int rv30_parse_slice_header(RV34DecContext *r, GetBitContext *gb, SliceIn
     skip_bits1(gb);
     si->pts = get_bits(gb, 13);
     rpr = get_bits(gb, r->rpr);
-    if(!rpr){
+    if(rpr){
+        w = r->s.avctx->extradata[6 + rpr*2] << 2;
+        h = r->s.avctx->extradata[7 + rpr*2] << 2;
+    }
     si->width  = w;
     si->height = h;
-    }else{
-        si->width  = r->s.avctx->extradata[6 + rpr*2] << 2;
-        si->height = r->s.avctx->extradata[7 + rpr*2] << 2;
-    }
     mb_size = ((w + 15) >> 4) * ((h + 15) >> 4);
     mb_bits = ff_rv34_get_start_offset(gb, mb_size);
     si->start = get_bits(gb, mb_bits);