diff -uNrp c/common/common.c b/common/common.c
--- c/common/common.c	2008-09-25 17:44:51 +0300
+++ b/common/common.c	2008-09-25 17:45:50 +0300
@@ -44,6 +44,8 @@ void    x264_param_default( x264_param_t
     /* CPU autodetect */
     param->cpu = x264_cpu_detect();
     param->i_threads = 1;
+    param->i_threads_boost = 0;
+    param->i_thread_input_boost = 0;
     param->b_deterministic = 1;
 
     /* Video properties */
@@ -267,6 +269,14 @@ int x264_param_parse( x264_param_t *p, c
         else
             p->i_threads = atoi(value);
     }
+    OPT("threads-boost")
+    {
+        p->i_threads_boost = atoi(value);
+    }
+    OPT("thread-input-boost")
+    {
+        p->i_thread_input_boost = atoi(value);
+    }
     OPT("thread-queue")
     {
         if( !strcmp(value, "auto") )
diff -uNrp c/encoder/encoder.c b/encoder/encoder.c
--- c/encoder/encoder.c	2008-09-25 17:44:51 +0300
+++ b/encoder/encoder.c	2008-09-25 17:46:09 +0300
@@ -385,6 +385,8 @@ static int x264_validate_parameters( x26
         return -1;
     }
 
+    h->param.i_threads_boost = x264_clip3( h->param.i_threads_boost, -2, 2 );
+    h->param.i_thread_input_boost = x264_clip3( h->param.i_thread_input_boost, -2, 2 );
     if( h->param.i_threads == 0 )
         h->param.i_threads = x264_cpu_num_processors() * 3/2;
     h->param.i_threads = x264_clip3( h->param.i_threads, 1, X264_THREAD_MAX );
@@ -833,8 +835,15 @@ x264_t *x264_encoder_open   ( x264_param
 
     if( h->param.i_threads > 1 )
     {
+        pthread_attr_t t_attr;
+        struct sched_param prio;
+        prio.sched_priority = h->param.i_threads_boost;
+
+        pthread_attr_init(&t_attr);
+        pthread_attr_setschedparam(&t_attr, &prio);
+
         for( i = 0; i < h->param.i_threads; i++ )
-            x264_pthread_create( &h->thread_handle[i], NULL, (void*)x264_slices_write_thread, h );
+            x264_pthread_create( &h->thread_handle[i], &t_attr, (void*)x264_slices_write_thread, h );
     }
 
     return h;
diff -uNrp c/muxers.c b/muxers.c
--- c/muxers.c	2008-09-25 17:44:26 +0300
+++ b/muxers.c	2008-09-25 17:46:53 +0300
@@ -429,6 +429,7 @@ typedef struct {
     int frame_total;
     int in_progress;
     struct thread_input_arg_t *next_args;
+    int priority;
 } thread_input_t;
 
 typedef struct thread_input_arg_t {
@@ -442,6 +443,7 @@ int open_file_thread( char *psz_filename
 {
     thread_input_t *h = malloc(sizeof(thread_input_t));
     x264_picture_alloc( &h->pic, X264_CSP_I420, p_param->i_width, p_param->i_height );
+    h->priority = p_param->i_thread_input_boost;
     h->p_read_frame = p_read_frame;
     h->p_close_infile = p_close_infile;
     h->p_handle = *p_handle;
@@ -494,7 +496,14 @@ int read_frame_thread( x264_picture_t *p
         h->next_frame =
         h->next_args->i_frame = i_frame+1;
         h->next_args->pic = &h->pic;
-        x264_pthread_create( &h->tid, NULL, (void*)read_frame_thread_int, h->next_args );
+
+        pthread_attr_t t_attr;
+        struct sched_param prio;
+        prio.sched_priority = h->priority;
+        pthread_attr_init(&t_attr);
+        pthread_attr_setschedparam(&t_attr, &prio);
+
+        x264_pthread_create( &h->tid, &t_attr, (void*)read_frame_thread_int, h->next_args );
         h->in_progress = 1;
     }
     else
diff -uNrp c/x264.c b/x264.c
--- c/x264.c	2008-09-25 17:44:51 +0300
+++ b/x264.c	2008-09-25 17:47:30 +0300
@@ -326,8 +326,17 @@ static void Help( x264_param_t *defaults
     H0( "      --no-psnr               Disable PSNR computation\n" );
     H0( "      --no-ssim               Disable SSIM computation\n" );
     H0( "      --threads <integer>     Parallel encoding\n" );
+    H1( "      --threads-boost <integer> Tune priority for encoding threads [%d]\n"
+        "                                    -2: LOWEST\n"
+        "                                    -1: BELOW_NORMAL\n"
+        "                                     0: NORMAL\n"
+        "                                     1: ABOVE_NORMAL\n"
+        "                                     2: HIGHEST\n",
+                                       defaults->i_threads_boost );
     H1( "      --thread-queue <integer> Number of delay frames for thread sync\n" );
     H0( "      --thread-input          Run Avisynth in its own thread\n" );
+    H1( "      --thread-input-boost <integer> Tune priority for input thread (Values as in 'threads-boost') [%d]\n",
+                                       defaults->i_thread_input_boost );
     H1( "      --non-deterministic     Slightly improve quality of SMP, at the cost of repeatability\n" );
     H1( "      --asm <integer>         Override CPU detection\n" );
     H1( "      --no-asm                Disable all CPU optimizations\n" );
@@ -454,6 +463,8 @@ static int  Parse( int argc, char **argv
             { "zones",   required_argument, NULL, 0 },
             { "qpfile",  required_argument, NULL, OPT_QPFILE },
             { "threads", required_argument, NULL, 0 },
+            { "threads-boost", required_argument, NULL, 0 },
+            { "thread-input-boost", required_argument, NULL, 0 },
             { "thread-queue", required_argument, NULL, 0 },
             { "thread-input", no_argument,  NULL, OPT_THREAD_INPUT },
             { "non-deterministic", no_argument, NULL, 0 },
diff -uNrp c/x264.h b/x264.h
--- c/x264.h	2008-09-25 17:44:51 +0300
+++ b/x264.h	2008-09-25 17:47:43 +0300
@@ -151,6 +151,8 @@ typedef struct x264_param_t
     /* CPU flags */
     unsigned int cpu;
     int         i_threads;       /* encode multiple frames in parallel */
+    int         i_threads_boost; /* priority of encoding threads */
+    int         i_thread_input_boost; /* priority of input thread */
     int         i_thread_queue;  /* number of frames to prepare in advance (>= i_threads) */
     int         b_deterministic; /* whether to allow non-deterministic optimizations when threaded */