diff --git a/encoder/ratecontrol.c b/encoder/ratecontrol.c
index 103e73b..4003e7b 100644
--- a/encoder/ratecontrol.c
+++ b/encoder/ratecontrol.c
@@ -1348,21 +1348,6 @@ static float rate_estimate_qscale( x264_t *h )
                           + h->stat.i_slice_size[SLICE_TYPE_P]
                           + h->stat.i_slice_size[SLICE_TYPE_B]);
 
-    if( h->param.i_threads > 1 )
-    {
-        int j = h->rc - h->thread[0]->rc;
-        int i;
-        for( i=1; i<h->param.i_threads; i++ )
-        {
-            x264_t *t = h->thread[ (j+i)%h->param.i_threads ];
-            double bits = t->rc->frame_size_planned;
-            if( !t->b_thread_active )
-                continue;
-            bits  = X264_MAX(bits, x264_ratecontrol_get_estimated_size(t));
-            total_bits += (int64_t)bits;
-        }
-    }
-
     if( rcc->b_2pass )
     {
         rce = *rcc->rce;
@@ -1415,10 +1400,15 @@ static float rate_estimate_qscale( x264_t *h )
         if( rcc->b_2pass )
         {
             //FIXME adjust abr_buffer based on distance to the end of the video
-            int64_t diff = total_bits - (int64_t)rce.expected_bits;
+            int64_t diff;
+
+            if( h->fenc->i_frame < h->param.i_threads )
+                diff = total_bits + (int64_t)h->fenc->i_frame * rcc->bitrate / rcc->fps - (int64_t)rce.expected_bits;
+            else
+                diff = total_bits + (int64_t)(h->param.i_threads - 1) * rcc->bitrate / rcc->fps - (int64_t)rce.expected_bits;
             q = rce.new_qscale;
             q /= x264_clip3f((double)(abr_buffer - diff) / abr_buffer, .5, 2);
-            if( h->fenc->i_frame > 30 )
+            if( h->fenc->i_frame + 1 - h->param.i_threads >= rcc->fps && rcc->expected_bits_sum > 0)
             {
                 /* Adjust quant based on the difference between
                  * achieved and expected bitrate so far */
@@ -1491,7 +1481,7 @@ static float rate_estimate_qscale( x264_t *h )
                 wanted_bits = i_frame_done * rcc->bitrate / rcc->fps;
                 if( wanted_bits > 0 )
                 {
-                    abr_buffer *= X264_MAX( 1, sqrt(i_frame_done/25) );
+                    abr_buffer *= X264_MAX( 1, sqrt(i_frame_done / rcc->fps) );
                     overflow = x264_clip3f( 1.0 + (total_bits - wanted_bits) / abr_buffer, .5, 2 );
                     q *= overflow;
                 }