avformat/matroskaenc: Don't write \0 unnecessarily

Writing the duration SimpleTag is special: It's size is
reserved in advance via an EBML Void element (if seekable)
and this reserved space is overwritten when writing the trailer;
it does not use put_ebml_string().

The string to write is created via snprintf on a buffer
of size 20; this buffer is then written via put_ebml_binary()
with a size of 20.

EBML strings need not be zero-terminated; if not, they
are implicitly terminated by the element's length field.
snprintf() always zero-terminates the buffer, i.e.
the last byte can be discarded when using an EBML string.
This patch does this.

The FATE changes are as expected: One byte saved for every
track; the only exception is the matroska-qt-mode test:
An additional byte is saved because an additional byte
could be saved from the enclosing Tags length field.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/tests/ref/fate/matroska-dovi-write-config8 b/tests/ref/fate/matroska-dovi-write-config8
index de90101a55..55fe191047 100644
--- a/tests/ref/fate/matroska-dovi-write-config8
+++ b/tests/ref/fate/matroska-dovi-write-config8
@@ -1,5 +1,5 @@
-56eea905c35996a729371372dd3113f9 *tests/data/fate/matroska-dovi-write-config8.matroska
-3600609 tests/data/fate/matroska-dovi-write-config8.matroska
+0730145aa317d800cb4bde0e3a38bb8d *tests/data/fate/matroska-dovi-write-config8.matroska
+3600607 tests/data/fate/matroska-dovi-write-config8.matroska
 #extradata 0:      551, 0xa18acf66
 #extradata 1:        2, 0x00340022
 #tb 0: 1/1000