diff -r -u x264-original/common/common.c x264-4part/common/common.c
--- x264-original/common/common.c	2008-07-23 20:00:38.000000000 -0700
+++ x264-4part/common/common.c	2008-07-29 00:00:32.000000000 -0700
@@ -141,6 +141,10 @@
 
     param->b_repeat_headers = 1;
     param->b_aud = 0;
+
+    param->athresh = 75;
+    param->bthresh = 50;
+    param->cthresh = 25;
 }
 
 static int parse_enum( const char *arg, const char * const *names, int *dst )
@@ -554,6 +558,12 @@
         p->b_repeat_headers = !atobool(value);
     OPT("repeat-headers")
         p->b_repeat_headers = atobool(value);
+    OPT("a-thresh")
+        p->athresh = atoi(value);
+    OPT("b-thresh")
+        p->bthresh = atoi(value);
+    OPT("c-thresh")
+        p->cthresh = atoi(value);
     else
         return X264_PARAM_BAD_NAME;
 #undef OPT
diff -r -u x264-original/config.h x264-4part/config.h
--- x264-original/config.h	2008-07-26 10:11:41.000000000 -0700
+++ x264-4part/config.h	2008-07-29 02:45:02.000000000 -0700
@@ -1,4 +1,4 @@
 #define fseek fseeko
 #define ftell ftello
-#define X264_VERSION " r915 14046ae"
-#define X264_POINTVER "0.60.915 14046ae"
+#define X264_VERSION " r915M 14046ae"
+#define X264_POINTVER "0.60.915M 14046ae"
diff -r -u x264-original/encoder/analyse.c x264-4part/encoder/analyse.c
--- x264-original/encoder/analyse.c	2008-07-23 20:00:37.000000000 -0700
+++ x264-4part/encoder/analyse.c	2008-07-31 16:05:49.000000000 -0700
@@ -1034,6 +1034,12 @@
     int *p_halfpel_thresh = /*h->mb.pic.i_fref[0]>1 ? &i_halfpel_thresh : */NULL;
     int i;
     int i_maxref = h->mb.pic.i_fref[0]-1;
+    int s_ref[16][2] = { { 0,INT_MAX},{ 1,INT_MAX},{ 2,INT_MAX},{ 3,INT_MAX},
+                         { 4,INT_MAX},{ 5,INT_MAX},{ 6,INT_MAX},{ 7,INT_MAX},
+                         { 8,INT_MAX},{ 9,INT_MAX},{10,INT_MAX},{11,INT_MAX},
+                         {12,INT_MAX},{13,INT_MAX},{14,INT_MAX},{15,INT_MAX} };
+    int u_ref[16][2] = {{0}};
+    int n,swapped,rtmp,ctmp;
 
     h->mb.i_partition = D_8x8;
 
@@ -1059,31 +1065,70 @@
         x264_me_t *l0m = &a->l0.me8x8[i];
         const int x8 = i%2;
         const int y8 = i/2;
+        const int r_maxref = (i == 0) ? i_maxref :
+                             (i == 1) ? ((i_maxref+1)*h->param.athresh)/100 :
+                             (i == 2) ? ((i_maxref+1)*h->param.bthresh)/100 :
+                                        ((i_maxref+1)*h->param.cthresh)/100 ;
 
         m.i_pixel = PIXEL_8x8;
         m.p_cost_mv = a->p_cost_mv;
 
         LOAD_FENC( &m, p_fenc, 8*x8, 8*y8 );
         l0m->cost = INT_MAX;
-        for( i_ref = 0; i_ref <= i_maxref; i_ref++ )
+        for( i_ref = 0; i_ref <= r_maxref; i_ref++ )
         {
-            const int i_ref_cost = REF_COST( 0, i_ref );
+            const int r_ref = s_ref[i_ref][0];
+            const int i_ref_cost = REF_COST( 0, r_ref );
             i_halfpel_thresh -= i_ref_cost;
             m.i_ref_cost = i_ref_cost;
-            m.i_ref = i_ref;
+            m.i_ref = r_ref;
 
-            LOAD_HPELS( &m, h->mb.pic.p_fref[0][i_ref], 0, i_ref, 8*x8, 8*y8 );
-            x264_macroblock_cache_ref( h, 2*x8, 2*y8, 2, 2, 0, i_ref );
+            LOAD_HPELS( &m, h->mb.pic.p_fref[0][r_ref], 0, r_ref, 8*x8, 8*y8 );
+            x264_macroblock_cache_ref( h, 2*x8, 2*y8, 2, 2, 0, r_ref );
             x264_mb_predict_mv( h, 0, 4*i, 2, m.mvp );
-            x264_me_search_ref( h, &m, a->l0.mvc[i_ref], i+1, p_halfpel_thresh );
+            x264_me_search_ref( h, &m, a->l0.mvc[r_ref], i+1, p_halfpel_thresh );
 
             m.cost += i_ref_cost;
             i_halfpel_thresh += i_ref_cost;
-            *(uint32_t*)a->l0.mvc[i_ref][i+1] = *(uint32_t*)m.mv;
+            *(uint32_t*)a->l0.mvc[r_ref][i+1] = *(uint32_t*)m.mv;
 
             if( m.cost < l0m->cost )
                 h->mc.memcpy_aligned( l0m, &m, sizeof(x264_me_t) );
+
+            u_ref[i_ref][0] = r_ref;
+            u_ref[i_ref][1] = m.cost;
+        }
+
+        if( i != 3 ) {
+            /* update ref list */
+            for( i_ref = 0; i_ref <= r_maxref; i_ref++ ) {
+                for( n = 0; n <= r_maxref; n++ ) {
+                    if( s_ref[n][1] != INT_MAX && u_ref[i_ref][0] == s_ref[n][0] ) {
+                        s_ref[n][1] += u_ref[i_ref][1];
+                        s_ref[n][1] /= 2;
+                    }
+                }
+            }
+            
+            /* sort ref list */
+            n = i_maxref;   // sort all refs incase c > b || b > a
+            do {
+                swapped = 0;
+                n--;
+                for( i_ref = 0; i_ref < n; i_ref++ ) {
+                    if( s_ref[i_ref][1] > s_ref[i_ref+1][1] ) {
+                        rtmp = s_ref[i_ref+1][0];
+                        ctmp = s_ref[i_ref+1][1];
+                        s_ref[i_ref+1][0] = s_ref[i_ref][0];
+                        s_ref[i_ref+1][1] = s_ref[i_ref][1];
+                        s_ref[i_ref][0] = rtmp;
+                        s_ref[i_ref][1] = ctmp;
+                        swapped = 1;
+                    }
+                }
+            } while ( swapped );
         }
+
         x264_macroblock_cache_mv_ptr( h, 2*x8, 2*y8, 2, 2, 0, l0m->mv );
         x264_macroblock_cache_ref( h, 2*x8, 2*y8, 2, 2, 0, l0m->i_ref );
 
diff -r -u x264-original/x264.c x264-4part/x264.c
--- x264-original/x264.c	2008-07-23 20:00:38.000000000 -0700
+++ x264-4part/x264.c	2008-07-29 00:02:59.000000000 -0700
@@ -471,6 +471,9 @@
             { "transfer", required_argument, NULL, 0 },
             { "colormatrix", required_argument, NULL, 0 },
             { "chromaloc", required_argument, NULL, 0 },
+            { "a-thresh", required_argument, NULL, 0 },
+            { "b-thresh", required_argument, NULL, 0 },
+            { "c-thresh", required_argument, NULL, 0 },
             {0, 0, 0, 0}
         };
 
diff -r -u x264-original/x264.h x264-4part/x264.h
--- x264-original/x264.h	2008-07-23 20:00:39.000000000 -0700
+++ x264-4part/x264.h	2008-07-29 00:03:31.000000000 -0700
@@ -289,6 +289,11 @@
     int b_aud;                  /* generate access unit delimiters */
     int b_repeat_headers;       /* put SPS/PPS before each keyframe */
     int i_sps_id;               /* SPS and PPS id number */
+
+    /* 4part p8x8 ref search */
+    int athresh;
+    int bthresh;
+    int cthresh;
 } x264_param_t;
 
 typedef struct {
diff -r -u x264-original/x264.pc x264-4part/x264.pc
--- x264-original/x264.pc	2008-07-26 10:11:41.000000000 -0700
+++ x264-4part/x264.pc	2008-07-29 02:45:02.000000000 -0700
@@ -5,6 +5,6 @@
 
 Name: x264
 Description: H.264 (MPEG4 AVC) encoder library
-Version: 0.60.915 14046ae
+Version: 0.60.915M 14046ae
 Libs: -L${exec_prefix}/lib -lx264 -lpthread
 Cflags: -I${prefix}/include