Convert BD audio from DTS-HD to Dolby 5.1 AC3 without video?

[agent154]

I've ripped one of my bluray discs that have a DTS-HD main audio track, and I want to include both the DTS-HD audio and a second AC3 5.1 audio in an mkv file for compatability. Problem is, I've already encoded the movie to MKV and what I thought would be 5.1 was just 6 channel discrete, and it's being read by my receiver as 2.0. How can I take the ripped m2ts file, rip out the DTS-HD track and convert it to a dolby digital/surround 5.1 so I can re-mux it into the MKV file?

Thanks.

[agent154]

Solved it after extensive research and trial/error.

Used tsmuxer to demux the dts-hd (and at the same time, convert it to plain DTS). Then used eac3to to convert to AC3. Had problems with the second step for a bit because it refused to convert directly. Had to first downsample it from 6.1 to 5.1 using -down6 before it would let me do the conversion.