Sat Jan 06, 2024 10:44 pm
If I understand correctly, you are trying to hardcode all subs, both forced and parent language.
Dump the .mkv into mkvtoolnix and check to determine what existing subtitle files are present, most probably the forced subtitle for the Osage speaking parts, from what I can gather from your post. If you need to edit any of the existing subtitle files, use mkvextract to pull the files.
You can then add edited or additional subtitle files within the .mkv container. You can view as an .mkv file on most players. An example to use is SMPlayer, which will allow you to run two subtitle streams simultaneously. You can then preview the combination of forced and your selected subtitles. Any location, OCR, sync or grammar/spelling errors can be addressed prior to format conversion.
Am not familiar with the iSkysoft converter. Most video editors though will recognize all subtitles within this container format.
Combining and exporting might require multiple steps, depending on your apps subtitles’ options. You might be required to do stages if it only addresses one subtitle selection; an initial hardcoded video conversion for the Osage parts, then a follow up for hardcoding your selected subtitles.
An alternative option would be to use a video editor such as Handbrake. This gives you options for “Forced”, “Burn In” and “Default” for all subtitle selections prior to conversion.
My recollection is that subtitle format of .srt is required for the hardcoded option.