diff --git a/libavcodec/vc1_block.c b/libavcodec/vc1_block.c index 680227cfe8..2513273064 100644 --- a/libavcodec/vc1_block.c +++ b/libavcodec/vc1_block.c @@ -388,6 +388,12 @@ static inline int ff_vc1_pred_dc(MpegEncContext *s, int overlap, int pq, int n, int q1, q2 = 0; int dqscale_index; + /* scale predictors if needed */ + q1 = s->current_picture.qscale_table[mb_pos]; + dqscale_index = s->y_dc_scale_table[q1] - 1; + if (dqscale_index < 0) + return 0; + wrap = s->block_wrap[n]; dc_val = s->dc_val[0] + s->block_index[n]; @@ -397,11 +403,7 @@ static inline int ff_vc1_pred_dc(MpegEncContext *s, int overlap, int pq, int n, c = dc_val[ - 1]; b = dc_val[ - 1 - wrap]; a = dc_val[ - wrap]; - /* scale predictors if needed */ - q1 = s->current_picture.qscale_table[mb_pos]; - dqscale_index = s->y_dc_scale_table[q1] - 1; - if (dqscale_index < 0) - return 0; + if (c_avail && (n != 1 && n != 3)) { q2 = s->current_picture.qscale_table[mb_pos - 1]; if (q2 && q2 != q1)