diff --git a/ivfenc.c b/ivfenc.c
new file mode 100644
index 0000000..fa92566
--- /dev/null
+++ b/ivfenc.c
@@ -0,0 +1,62 @@
+/*
+ *  Copyright (c) 2013 The WebM project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "./ivfenc.h"
+
+#include "./tools_common.h"
+#include "vpx/vpx_encoder.h"
+#include "vpx_ports/mem_ops.h"
+
+void ivf_write_file_header(FILE *outfile,
+                           const struct vpx_codec_enc_cfg *cfg,
+                           unsigned int fourcc,
+                           int frame_cnt) {
+  char header[32];
+
+  if (cfg->g_pass != VPX_RC_ONE_PASS && cfg->g_pass != VPX_RC_LAST_PASS)
+    return;
+
+  header[0] = 'D';
+  header[1] = 'K';
+  header[2] = 'I';
+  header[3] = 'F';
+  mem_put_le16(header + 4,  0);                 /* version */
+  mem_put_le16(header + 6,  32);                /* headersize */
+  mem_put_le32(header + 8,  fourcc);            /* four CC */
+  mem_put_le16(header + 12, cfg->g_w);          /* width */
+  mem_put_le16(header + 14, cfg->g_h);          /* height */
+  mem_put_le32(header + 16, cfg->g_timebase.den); /* rate */
+  mem_put_le32(header + 20, cfg->g_timebase.num); /* scale */
+  mem_put_le32(header + 24, frame_cnt);         /* length */
+  mem_put_le32(header + 28, 0);                 /* unused */
+
+  (void) fwrite(header, 1, 32, outfile);
+}
+
+void ivf_write_frame_header(FILE *outfile, const struct vpx_codec_cx_pkt *pkt) {
+  char header[12];
+  vpx_codec_pts_t pts;
+
+  if (pkt->kind != VPX_CODEC_CX_FRAME_PKT)
+    return;
+
+  pts = pkt->data.frame.pts;
+  mem_put_le32(header, (int)pkt->data.frame.sz);
+  mem_put_le32(header + 4, pts & 0xFFFFFFFF);
+  mem_put_le32(header + 8, pts >> 32);
+
+  (void) fwrite(header, 1, 12, outfile);
+}
+
+void ivf_write_frame_size(FILE *outfile, size_t size) {
+  char header[4];
+  mem_put_le32(header, (int)size);
+  (void) fwrite(header, 1, 4, outfile);
+}