m2pa_codec: use standard 'undefined' for not-present mtp3 portion
diff --git a/src/m2pa_codec.erl b/src/m2pa_codec.erl
index 71caf7c..1eeb5f9 100644
--- a/src/m2pa_codec.erl
+++ b/src/m2pa_codec.erl
@@ -37,7 +37,7 @@
{undefined, Ret}
end;
parse_m2pa_msgt(?M2PA_CLASS_M2PA, ?M2PA_TYPE_USER, 16, <<>>) ->
- {empty, []};
+ {undefined, []};
parse_m2pa_msgt(?M2PA_CLASS_M2PA, ?M2PA_TYPE_USER, Len, RemainIn) ->
<<Pri:1, _:7, Mtp3Bin/binary>> = RemainIn,
Mtp3 = mtp3_codec:parse_mtp3_msg(Mtp3Bin),
@@ -51,7 +51,7 @@
fwd_seq_nr = FSN, back_seq_nr = BSN,
mtp3 = Mtp3, parameters = Params}}.
-encode_m2pa_msgt(?M2PA_CLASS_M2PA, ?M2PA_TYPE_USER, empty, _Params) ->
+encode_m2pa_msgt(?M2PA_CLASS_M2PA, ?M2PA_TYPE_USER, undefined, _Params) ->
<<>>;
encode_m2pa_msgt(?M2PA_CLASS_M2PA, ?M2PA_TYPE_USER, Mtp3, _Params) when is_binary(Mtp3) ->
<<0:1, 0:7, Mtp3/binary>>;