Downconvert DTS to stereo

[mew1033]

I recently went through an adventure converting an HD .mkv video file to a DVD+R DL. The resulting DVD's audio doesn't work in most DVD players. I just found out that it's because the audio track is DTS 6 channel. Obviously, that's not going to work in anything that doesn't have the hardware to play it.
I used AVStodvd, and I still have the source and project file.

How would I go about extracting the audio, downsampleing (is that the right word) it to a simple stereo feed, and re embedding it in the DVD. I don't need to keep the original 6 channel audio. In fact, I'd rather not so that I can save space.
Another option I have is to just open up the AVStodvd project file and tell it to convert the audio to ...... WAV? MP2? I'm not sure... When I do that, I get a warning saying that 6 channels isn't supported by WAV or MP2 and it switches to AC3.

If neither of those are good ways to achieve what I want, then what would be?

Thanks!

[johns0]

Load the mkv into eac3to gui and select 448 ac3,then use mkvmerge to mux the ac3 with the mkv and uncheck the dts audio and save,then encode the new mkv,if you need to read on how to use the apps i mentioned theres dozens of threads and help guides you can search.