#0  0x000000000045e199 in x264_plane_copy_mmxext ()
#1  0x00000000004253da in x264_frame_copy_picture (h=0xa30080, dst=0xff8500, src=0x7fff3ef94630) at common/frame.c:233
#2  0x0000000000413123 in x264_encoder_encode (h=0xa30080, pp_nal=<value optimized out>, pi_nal=<value optimized out>, 
    pic_in=0x7fff3ef94630, pic_out=<value optimized out>) at encoder/encoder.c:1678
#3  0x0000000000402c56 in Encode_frame (h=0x7f026803cb50, hout=0x9cd010, pic=0x18) at x264.c:1130
#4  0x00000000004043f9 in main (argc=<value optimized out>, argv=<value optimized out>) at x264.c:1236

diff --git a/muxers.c b/muxers.c
index 7100877..86b20e9 100644
--- a/muxers.c
+++ b/muxers.c
@@ -41,6 +41,9 @@
 #include <gpac/isomedia.h>
 #endif
 
+#include <libavformat/avformat.h>
+#include <libavcodec/avcodec.h>
+
 static int64_t gcd( int64_t a, int64_t b )
 {
     while( 1 )
@@ -426,6 +429,82 @@ int close_file_avis( hnd_t handle )
 }
 #endif
 
+/* libavcodec file input */
+typedef struct
+{
+    AVFormatContext *context;
+    const char *file;
+    int stream_id, next_frame;
+} lavc_input_t;
+
+int open_file_lavc( char *psz_filename, hnd_t *p_handle, x264_param_t *p_param )
+{
+    lavc_input_t *h = malloc( sizeof(lavc_input_t) );
+    av_register_all();
+    h->context = avformat_alloc_context();
+    h->context->flags |= AVSEEK_FLAG_ANY;
+    h->next_frame = 0;
+    h->file = psz_filename;
+    if( av_open_input_file( &h->context, psz_filename, NULL, 0, NULL ) != 0 || av_find_stream_info( h->context ) < 0)
+        return -1;
+    int i = 0;
+	while( i < h->context->nb_streams && h->context->streams[i]->codec->codec_type != CODEC_TYPE_VIDEO )
+        i++;
+    if( i == h->context->nb_streams )
+        return -1;
+    h->stream_id = i;
+    AVCodecContext *c = h->context->streams[i]->codec;
+    if( avcodec_open( c, avcodec_find_decoder( c->codec_id ) ) != 0 )
+        return -1;
+    p_param->i_width = c->width;
+    p_param->i_height = c->height;
+    *p_handle = (hnd_t)h;
+    return 0;
+}
+
+int get_frame_total_lavc( hnd_t handle )
+{
+    return 0;
+}
+
+int read_frame_lavc( x264_picture_t *p_pic, hnd_t handle, int i_frame )
+{
+    int width, height, finished = 0;
+    AVPacket pkt;
+    lavc_input_t *h = handle;
+    av_init_packet( &pkt );
+    while( i_frame < h->next_frame )
+    {
+        av_read_frame( h->context, &pkt );
+        if( pkt.stream_index == h->stream_id )
+            h->next_frame ++;
+        av_free_packet( &pkt );
+    }
+    av_init_packet( &pkt );
+    AVFrame *frame = avcodec_alloc_frame();
+    while( !finished && av_read_frame( h->context, &pkt ) >= 0 )
+    {
+        if( pkt.stream_index == h->stream_id )
+            avcodec_decode_video2( h->context->streams[h->stream_id]->codec, frame, &finished, &pkt );
+        av_free_packet( &pkt );
+    }
+    width = h->context->streams[h->stream_id]->codec->width;
+    height = h->context->streams[h->stream_id]->codec->height;
+    h->next_frame ++;
+    memcpy( p_pic->img.plane[0], frame->data[0], 3 * width * height / 2);
+    int i;
+    for( i = 0; i < 3; i ++ )
+        p_pic->img.i_stride[i] = frame->linesize[i];
+    av_free( frame );
+    return 0;
+}
+
+int close_file_lavc( hnd_t handle )
+{
+    lavc_input_t *h = handle;
+    av_free( h->context );
+    return 0;
+}
 
 #ifdef HAVE_PTHREAD
 typedef struct
diff --git a/muxers.h b/muxers.h
index aaede1c..62872bd 100644
--- a/muxers.h
+++ b/muxers.h
@@ -41,6 +41,11 @@ int get_frame_total_avis( hnd_t handle );
 int read_frame_avis( x264_picture_t *p_pic, hnd_t handle, int i_frame );
 int close_file_avis( hnd_t handle );
 
+int open_file_lavc( char *psz_filename, hnd_t *p_handle, x264_param_t *p_param );
+int get_frame_total_lavc( hnd_t handle );
+int read_frame_lavc( x264_picture_t *p_pic, hnd_t handle, int i_frame );
+int close_file_lavc( hnd_t handle );
+
 int open_file_thread( char *psz_filename, hnd_t *p_handle, x264_param_t *p_param );
 int get_frame_total_thread( hnd_t handle );
 int read_frame_thread( x264_picture_t *p_pic, hnd_t handle, int i_frame );
diff --git a/x264.c b/x264.c
index f7786ce..cd49fc5 100644
--- a/x264.c
+++ b/x264.c
@@ -538,6 +538,7 @@ static int  Parse( int argc, char **argv,
     char *profile = NULL;
     int b_avis = 0;
     int b_y4m = 0;
+    int b_lavc = 0;
     int b_thread_input = 0;
     int b_turbo = 1;
     int b_pass1 = 0;
@@ -959,8 +960,10 @@ generic_option:
         b_avis = 1;
     if( !strncasecmp( psz, ".y4m", 4 ) )
         b_y4m = 1;
+    if( !strncasecmp( psz, ".mkv", 4 ) )
+        b_lavc = 1;
 
-    if( !(b_avis || b_y4m) ) // raw yuv
+    if( !(b_avis || b_y4m || b_lavc) ) // raw yuv
     {
         if( optind > argc - 1 )
         {
@@ -984,7 +987,7 @@ generic_option:
         }
     }
 
-    if( !(b_avis || b_y4m) && ( !param->i_width || !param->i_height ) )
+    if( !(b_avis || b_y4m || b_lavc ) && ( !param->i_width || !param->i_height ) )
     {
         fprintf( stderr, "x264 [error]: Rawyuv input requires a resolution.\n" );
         return -1;
@@ -1013,6 +1016,13 @@ generic_option:
             p_read_frame = read_frame_y4m;
             p_close_infile = close_file_y4m;
         }
+        if( b_lavc )
+        {
+            p_open_infile = open_file_lavc;
+            p_get_frame_total = get_frame_total_lavc;
+            p_read_frame = read_frame_lavc;
+            p_close_infile = close_file_lavc;
+        }
 
         if( p_open_infile( psz_filename, &opt->hin, param ) )
         {
@@ -1171,6 +1181,10 @@ static int  Encode( x264_param_t *param, cli_opt_t *opt )
 
     opt->b_progress &= param->i_log_level < X264_LOG_DEBUG;
     i_frame_total = p_get_frame_total( opt->hin );
+    if( i_frame_total == -1 )
+    {
+        i_frame_total = opt->i_seek;
+    }
     i_frame_total -= opt->i_seek;
     if( ( i_frame_total == 0 || param->i_frame_total < i_frame_total )
         && param->i_frame_total > 0 )