I have an Mkv with fansubbed subtitles that are softsubs encoded in the file. Is there a way to make it hardsubbed (any format, so long as they are hardsubs)
VirtualDub to add the permanent .ssa subtitles to the video and save as a new AVI file.
MKVMerge to mux the new AVI to the original audio and recreate the MKV file.
Depending on the video and audio in the MKV file, I would demux the MKV, load the video into VirtualDub to add the hard subtitles and save the new AVI.
Mux the new AVI file from VirtualDub with the original audio to create a new MKV file.
This Afterdawn guide shows .srt files being converted to .ssa to load into VirtualDub, however, if the subtitle stream in the MKV file is .ssa, then no conversion is required.
If the MKV audio was converted to a WAV, it could be loaded into VirtualDub and the subsequent AVI saved with the audio - no conversion back to MKV required - unless personal preference.