Index: common/common.h
===================================================================
--- common/common.h	(revision 661)
+++ common/common.h	(working copy)
@@ -583,6 +583,12 @@
             /* Adaptive direct mv pred */
             int i_direct_score[2];
         } frame;
+        
+        /* Previous frame stats */
+        struct
+        {
+            int i_intra_cost;
+        } frame_prev;
 
         /* Cumulated stats */
 
Index: encoder/slicetype.c
===================================================================
--- encoder/slicetype.c	(revision 661)
+++ encoder/slicetype.c	(working copy)
@@ -247,6 +247,11 @@
 #undef TRY_BIDIR
 #undef SAVE_MVS
 
+/* Evaluate cost of a candidate frame (b), using p0 as L0
+ * and p1 as L1 references.
+ * 2 references different from b => B frame
+ * 1 references different from b => P frame
+ * 0 reference different from b => I frame */
 int x264_slicetype_frame_cost( x264_t *h, x264_mb_analysis_t *a,
                                x264_frame_t **frames, int p0, int p1, int b,
                                int b_intra_penalty )
@@ -323,8 +328,48 @@
     return i_score;
 }
 
-static int scenecut( x264_t *h, x264_frame_t *frame, int pdist )
+/* spatial detection for scene cut */
+static int scenecut_spatial( x264_t *h, x264_frame_t *frame, int prev_icost , int new_icost )
 {
+    int res = 0;
+    int idiff = abs(prev_icost - new_icost);
+    float f_bias;
+    int i_gop_size = frame->i_frame - h->frames.i_last_idr;
+    float f_thresh_max = h->param.i_scenecut_threshold / 100.0;
+    /* magic numbers pulled out of thin air */
+    float f_thresh_min = f_thresh_max * h->param.i_keyint_min
+                         / ( h->param.i_keyint_max * 4 );
+
+    if( h->param.i_keyint_min == h->param.i_keyint_max )
+        f_thresh_min= f_thresh_max;
+    if( i_gop_size < h->param.i_keyint_min / 4 )
+        f_bias = f_thresh_min / 4;
+    else if( i_gop_size <= h->param.i_keyint_min )
+        f_bias = f_thresh_min * i_gop_size / h->param.i_keyint_min;
+    else
+    {
+        f_bias = f_thresh_min
+                 + ( f_thresh_max - f_thresh_min )
+                   * ( i_gop_size - h->param.i_keyint_min )
+                   / ( h->param.i_keyint_max - h->param.i_keyint_min );
+    }
+
+    if (frame->i_frame < 2)
+        return res;
+    if( !(h->param.b_pre_scenecut) )
+        return res;
+
+    res = idiff >= prev_icost*.4*(1.0 - f_bias);
+
+
+    return res;
+}
+
+
+
+/* temporal detection for scene cut */
+static int scenecut_temporal( x264_t *h, x264_frame_t *frame, int pdist )
+{
     int icost = frame->i_cost_est[0][0];
     int pcost = frame->i_cost_est[pdist][0];
     float f_bias;
@@ -372,6 +417,9 @@
     int i_mb_count = (h->sps->i_mb_width - 2) * (h->sps->i_mb_height - 2);
     int cost1p0, cost2p0, cost1b1, cost2p1;
     int idr_frame_type;
+    int no_b_frames = 0;
+    int spacial_cut = 0;
+    int i_intra_cost_prev = h->stat.frame_prev.i_intra_cost;
 
     assert( h->frames.b_have_lowres );
 
@@ -390,29 +438,48 @@
 
     if( num_frames == 1 )
     {
-no_b_frames:
+        no_b_frames = 1;
+    }
+    else
+    {
+
+        cost2p1 = x264_slicetype_frame_cost( h, &a, frames, 0, 2, 2, 1 );
+        if( frames[2]->i_intra_mbs[2] > i_mb_count / 2 )
+            no_b_frames = 1;
+
+        if (!no_b_frames )
+        {
+            cost1b1 = x264_slicetype_frame_cost( h, &a, frames, 0, 2, 1, 0 );
+            cost1p0 = x264_slicetype_frame_cost( h, &a, frames, 0, 1, 1, 0 );
+            cost2p0 = x264_slicetype_frame_cost( h, &a, frames, 1, 2, 2, 0 );
+//          fprintf( stderr, "PP: %d + %d <=> BP: %d + %d \n",
+//                  cost1p0, cost2p0, cost1b1, cost2p1 );
+            if( cost1p0 + cost2p0 < cost1b1 + cost2p1 )
+                no_b_frames = 1;
+        }
+    }
+
+    //save intra cost
+    x264_slicetype_frame_cost( h, &a, frames, 0, 1, 1, 0 );
+    h->stat.frame_prev.i_intra_cost = frames[1]->i_cost_est[0][0];
+
+    if ( scenecut_spatial(h, frames[1], i_intra_cost_prev, frames[1]->i_cost_est[0][0]) )
+    {
+        no_b_frames = 1;
+        spacial_cut = 1;
+    }
+
+    if (no_b_frames)
+    {
         frames[1]->i_type = X264_TYPE_P;
         if( h->param.b_pre_scenecut )
         {
-            x264_slicetype_frame_cost( h, &a, frames, 0, 1, 1, 0 );
-            if( scenecut( h, frames[1], 1 ) )
+            if( scenecut_temporal( h, frames[1], 1 ) || spacial_cut)
                 frames[1]->i_type = idr_frame_type;
         }
         return;
     }
 
-    cost2p1 = x264_slicetype_frame_cost( h, &a, frames, 0, 2, 2, 1 );
-    if( frames[2]->i_intra_mbs[2] > i_mb_count / 2 )
-        goto no_b_frames;
-
-    cost1b1 = x264_slicetype_frame_cost( h, &a, frames, 0, 2, 1, 0 );
-    cost1p0 = x264_slicetype_frame_cost( h, &a, frames, 0, 1, 1, 0 );
-    cost2p0 = x264_slicetype_frame_cost( h, &a, frames, 1, 2, 2, 0 );
-//  fprintf( stderr, "PP: %d + %d <=> BP: %d + %d \n",
-//           cost1p0, cost2p0, cost1b1, cost2p1 );
-    if( cost1p0 + cost2p0 < cost1b1 + cost2p1 )
-        goto no_b_frames;
-
 // arbitrary and untuned
 #define INTER_THRESH 300
 #define P_SENS_BIAS (50 - h->param.i_bframe_bias)