Die meisten DE-Subs sind entweder als ISO-8859-1 oder als WINDOWS-1252 codiert, ANSI bezeichnet eigentlich etwas anderes
nämlich ein Norminstitut, wie die DIN... es wird oft als Bezeichnung für ASCII benutzt, also nur die folgenden Zeichen:
!"#$%&'()*+,-./0123456789:;<=>?
@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_
`abcdefghijklmnopqrstuvwxyz{|}~
Aber zurück zum Thema, da:
SUBTITLES
There are several text subtitle formats that can be embedded into Matroska(TM).
At the moment mkvmerge(1) supports only text, VobSub and Kate subtitle formats.
Text subtitles must be recoded to UTF-8 so that they can be displayed correctly
by a player (see the section about text files and character sets for an explanation how mkvmerge(1) converts between character sets).
Kate subtitles are already encoded in UTF-8 and do not have to be re-encoded.
[...]
TEXT FILES AND CHARACTER SET CONVERSIONS
Note: This section applies to all programs in MKVToolNix even if it only mentions mkvmerge(1).
All text in a Matroska(TM) file is encoded in UTF-8.
This means that mkvmerge(1) has to convert every text file it reads as well as every text given on the command line from one character set into UTF-8.
In return this also means that mkvmerge(1)'s output has to be converted back to that character set from UTF-8, e.g. if a non-English translation is used with --ui-language or for text originating from a Matroska(TM) file.
[...]
musst du den Untertitel vor dem muxen in UTF8 umwandeln, einfach in einem Text-Editor öffnen, und als UTF8 neu abspeichern...