I rip my Blu-rays to play on our WD TV Live (firmware 1.06.43_V), Macs and mobile devices (iPad, iPod, Samsung Galaxy Note II). There have been many issues over the last few years, with subtitles being the last one to solve.
I keep uncompressed mkv files to play on the WD TV Live (and as master copies) and transcode to m4v for all the other devices.
- Rip with Makemkv. I use an external Blu-ray drive on a MacBook Pro. Make sure all english subtitle tracks (forced only) are selected. VLC (2.0.6) plays subtitles correctly but the WD TV Live doesn't.
- Remux the mkv with MKVToolNix using the default settings - fixes the WD TV Live subtitles issue.
- Transcode with Handbrake (0.9.9 x86_64). Use the iPad profile and on the Subtitles tab select Foreign Audio Search, Forced Only, Burned In.