"hard burns" subtitles. This means the subtitles are written on top of the image permanently. They cannot be turned on or off like on the DVD.

Some movies modify an existing subtitle track with "forced" subtitles that only display during the foreign language segments, hiding the rest of that subtitle track at other times. You can use the Mac GUI "Forced Subtitles Only" option next to the subtitle track selector to request that only "forced" subtitles be displayed for the selected track. In the CLI use the --subtitle-forced option.

Do not select the forced option unless you know that there are forced subtitles, otherwise no subtitles will be displayed. You can use the "Autoselect" feature to discover whether there are forced subtitles (discussed below).

Some movies have special subtitle tracks that are always on but only have subtitles to display during the foreign language segments, and are otherwise blank. You can use the Mac GUI "Autoselect" subtitle language, or the CLI option --subtitle-scan to request that detect and enable these subtitle tracks.

The "forced" option may be used in conjunction with "Autoselect"/--subtitle-scan in order to look for forced subtitle when scanning for subtitle tracks to enable. If any subtitle tracks in the same language as the selected Audio language contains forced subtitles then that subtitle track will be selected. If no subtitle tracks contain forced subtitles then the normal 10% threshold algorithm is used to select a subtitle track.

It is recommended that both "Autoselect" and "Forced" be used in conjunction.

The autoselect algorithm used does not always work with movies with a lot of foreign language segments. The algorithm looks for a subtitle track with less than 10% of the subtitles than any other subtitle track in the same language as the Audio language.