I just use MX Player. haven't found anything I neesd to convert yet. With a custom codec, it can even mix down DTS 5.1 audio in MKV
Always read the OP's of a thread and the last 2 pages before asking questions, unless there has been an update - in which case, read the last 5 pages!

nexus 5 | SlimKat | ElementalX kernel | Philz Touch Recovery

I do NOT reply to support queries over PM.