diff --git a/libavcodec/bytestream.h b/libavcodec/bytestream.h
index 2d9ca47508..857e050ea2 100644
--- a/libavcodec/bytestream.h
+++ b/libavcodec/bytestream.h
@@ -198,6 +198,16 @@ static av_always_inline int bytestream2_tell_p(PutByteContext *p)
     return (int)(p->buffer - p->buffer_start);
 }
 
+static av_always_inline int bytestream2_size(GetByteContext *g)
+{
+    return (int)(g->buffer_end - g->buffer_start);
+}
+
+static av_always_inline int bytestream2_size_p(PutByteContext *p)
+{
+    return (int)(p->buffer_end - p->buffer_start);
+}
+
 static av_always_inline int bytestream2_seek(GetByteContext *g,
                                              int offset,
                                              int whence)
@@ -323,6 +333,32 @@ static av_always_inline unsigned int bytestream2_get_eof(PutByteContext *p)
     return p->eof;
 }
 
+static av_always_inline unsigned int bytestream2_copy_bufferu(PutByteContext *p,
+                                                              GetByteContext *g,
+                                                              unsigned int size)
+{
+    memcpy(p->buffer, g->buffer, size);
+    p->buffer += size;
+    g->buffer += size;
+    return size;
+}
+
+static av_always_inline unsigned int bytestream2_copy_buffer(PutByteContext *p,
+                                                             GetByteContext *g,
+                                                             unsigned int size)
+{
+    int size2;
+
+    if (p->eof)
+        return 0;
+    size  = FFMIN(g->buffer_end - g->buffer, size);
+    size2 = FFMIN(p->buffer_end - p->buffer, size);
+    if (size2 != size)
+        p->eof = 1;
+
+    return bytestream2_copy_bufferu(p, g, size2);
+}
+
 static av_always_inline unsigned int bytestream_get_buffer(const uint8_t **b,
                                                            uint8_t *dst,
                                                            unsigned int size)
diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index 94e718263a..15fa34c598 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -1696,7 +1696,8 @@ static int mov_write_ilst_tag(AVIOContext *pb, MOVMuxContext *mov,
     mov_write_string_metadata(s, pb, "\251wrt", "composer" , 1);
     mov_write_string_metadata(s, pb, "\251alb", "album"    , 1);
     mov_write_string_metadata(s, pb, "\251day", "date"     , 1);
-    mov_write_string_tag(pb, "\251too", LIBAVFORMAT_IDENT, 0, 1);
+    if (!mov_write_string_metadata(s, pb, "\251too", "encoding_tool", 1))
+        mov_write_string_tag(pb, "\251too", LIBAVFORMAT_IDENT, 0, 1);
     mov_write_string_metadata(s, pb, "\251cmt", "comment"  , 1);
     mov_write_string_metadata(s, pb, "\251gen", "genre"    , 1);
     mov_write_string_metadata(s, pb, "\251cpy", "copyright", 1);