diff --git a/src/common/ebml.cpp b/src/common/ebml.cpp
index a3068e4b7..2cb291d9c 100644
--- a/src/common/ebml.cpp
+++ b/src/common/ebml.cpp
@@ -515,3 +515,17 @@ remove_voids_from_master(EbmlElement *element) {
   if (master)
     DeleteChildren<EbmlVoid>(master);
 }
+
+int
+write_ebml_element_head(mm_io_c &out,
+                        EbmlId const &id,
+                        int64_t content_size) {
+	int id_size    = EBML_ID_LENGTH(id);
+	int coded_size = CodedSizeLength(content_size, 0);
+  uint8_t buffer[4 + 8];
+
+	id.Fill(buffer);
+	CodedValueLength(content_size, coded_size, &buffer[id_size]);
+
+  return out.write(buffer, id_size + coded_size);
+}
diff --git a/src/common/ebml.h b/src/common/ebml.h
index af5ec16ad..4ac0d08b0 100644
--- a/src/common/ebml.h
+++ b/src/common/ebml.h
@@ -45,6 +45,8 @@ int kt_get_a_bps(KaxTrackEntry &track);
 int kt_get_v_pixel_width(KaxTrackEntry &track);
 int kt_get_v_pixel_height(KaxTrackEntry &track);
 
+int write_ebml_element_head(mm_io_c &out, EbmlId const &id, int64_t content_size);
+
 #define is_id(e, ref) (EbmlId(*e) == EBML_ID(ref))
 #if !defined(EBML_INFO)
 #define EBML_INFO(ref)  ref::ClassInfos