From 27ed1a0dee0f49beb202e104b47d521a700827c1 Mon Sep 17 00:00:00 2001
From: Kostya Shishkov <kostya.shishkov@gmail.com>
Date: Fri, 21 Jul 2006 04:06:06 +0000
Subject: [PATCH] 1000l: scale DC predictors instead of predicted value.

Originally committed as revision 5808 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 libavcodec/vc1.c | 32 ++++++++++++++++++++------------
 1 file changed, 20 insertions(+), 12 deletions(-)

diff --git a/libavcodec/vc1.c b/libavcodec/vc1.c
index a18dbfa..fa1d9fa 100644
--- a/libavcodec/vc1.c
+++ b/libavcodec/vc1.c
@@ -1769,38 +1769,46 @@ static inline int 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];
+    if(c_avail && (n!= 1 && n!=3)) {
+        q2 = s->current_picture.qscale_table[mb_pos - 1];
+        if(q2 && q2 != q1)
+            c = (c * s->y_dc_scale_table[q2] * vc1_dqscale[s->y_dc_scale_table[q1] - 1] + 0x20000) >> 18;
+    }
+    if(a_avail && (n!= 2 && n!=3)) {
+        q2 = s->current_picture.qscale_table[mb_pos - s->mb_stride];
+        if(q2 && q2 != q1)
+            a = (a * s->y_dc_scale_table[q2] * vc1_dqscale[s->y_dc_scale_table[q1] - 1] + 0x20000) >> 18;
+    }
+    if(a_avail && c_avail && (n!=3)) {
+        int off = mb_pos;
+        if(n != 1) off--;
+        if(n != 2) off -= s->mb_stride;
+        q2 = s->current_picture.qscale_table[off];
+        if(q2 && q2 != q1)
+            b = (b * s->y_dc_scale_table[q2] * vc1_dqscale[s->y_dc_scale_table[q1] - 1] + 0x20000) >> 18;
+    }
 
     if(a_avail && c_avail) {
         if(abs(a - b) <= abs(b - c)) {
             pred = c;
             *dir_ptr = 1;//left
-            q2 = s->current_picture.qscale_table[mb_pos - 1];
         } else {
             pred = a;
             *dir_ptr = 0;//top
-            q2 = s->current_picture.qscale_table[mb_pos - s->mb_stride];
         }
     } else if(a_avail) {
         pred = a;
         *dir_ptr = 0;//top
-        q2 = s->current_picture.qscale_table[mb_pos - s->mb_stride];
     } else if(c_avail) {
         pred = c;
         *dir_ptr = 1;//left
-        q2 = s->current_picture.qscale_table[mb_pos - 1];
     } else {
         pred = 0;
         *dir_ptr = 1;//left
     }
 
-    /* scale coeffs if needed */
-    q1 = s->current_picture.qscale_table[mb_pos];
-    if(n && n<4) q2=q1;
-
-    if(q2 && q1!=q2) {
-        pred = (pred * s->y_dc_scale_table[q2] * vc1_dqscale[s->y_dc_scale_table[q1] - 1] + 0x20000) >> 18;
-    }
-
     /* update predictor */
     *dc_val_ptr = &dc_val[0];
     return pred;
-- 
2.7.4