I currently use MakeMKV to create an MKV file from my Blu-Rays and then use Handbrake to re-encode the file to decrease size.

My thought was to replace the Handbrake part with DBpoweramp Video Converter using the GPU encoder as it is so much quicker than Handbrake, however I have just converted 'Ip Man' and it hasn't taken any subtitles across.

I can't seem to find any options regarding subtitles but that may just be me.