LAV Splitter allows you to configure your preferred audio languages using three letter language codes. Simply create a comma separated list of your preferred language(s). A list of language codes can be found HERE.
The subtitle selection logic allows more complex selection rules that also take the current audio language into account. To use the complex logic you need to set "Subtitle Selection Mode" to "Advanced".
The advanced subtitle selection is explained below in a excerpt from the LAV Splitter readme:
The advanced mode uses a different syntax for the preferred language field to enable these rules. Instead of a single language tag, a combined tag of audio and subtitle language is required (separated by a colon). The most basic tag would look like this: “ger:eng”. In this case, the interpretation would be “If Audio is German, use English subtitles”.
Note: Even though this may feel similar to the selectors Haali’s Media Splitter offers, LAV’s implemention does not allow you to specify which audio stream is used through the advanced selectors, the audio language is only used to select which subtitles are used.
In addition to simply using two language tags, you can use the “*” character to match all languages, or the “off” token to disable subtitles. For example, following tag will enable any subtitles when the audio is english, and disable subtitles otherwise: “eng:*;*:off”.
As you’ve seen in the previous example, multiple rules can be concatenated using a semi-colon (or a space) to build rule chains. Again, everything is interpreted from left to right.
To complete the advanced mode, there are two flags for “default” and “forced” subtitles which are supported. These two flags only occur in the Matroska container (.mkv files). The flags are identified by their first letter, and appended to the subtitle language separated by a pipe character (“|”). As an example, following rule will select any “forced” subtitles, and turn off subtitles otherwise:
To finish the section about advanced subtitles, here some examples of rules to inspire you:
This is the rule equal to the “Default” subtitle mode with English as a preferred language.
Load English “forced” subtitles if audio is English, load German “forced” subtitles if audio is German, no subs otherwise.
English Audio: Turn subs off; French Audio: English subs; Any other audio: try to find subtitles flagged “default”.