converting 6 channel audio to 2 channel & putting 2 streams in a container

[qorda]

HiI have some MP4 and MKV video files with 6 channel AAC or 5.1 AC3 audio.
I do not have a surround sound system but 2 speakers and a subwoofer essentially a 2.1 output for both PC and TV.
With that when I play the files, all I can hear nicely is back ground music while dialogues are barely audible.
Please advise
1- What would be the best audio for my system
2- What programs may I use to make that conversion
3- How to keep the new audio and the original audio in the newly created file container
4- A brief advice on the method involved in steps 2 and 3.
My computer knowledge is modest so please keep the explanation easy to understand with less jargon where possible.
I would do such conversion occasionally so freeware should be advised with GUI as I am nil at command line.
Thank you for the help

[davexnet]

Perhaps create an mp3 audio for the 2-channel track? You could try the method I sometimes use,
which uses avisynth, directshowsource, ffdshow, Lame mp3 and Virtualdub. See post 10.
https://forum.videohelp.com/threads/357689-Low-volume-when-loading-external-audio-file-...ighlight=mixer

After this new audio is created, should be a simple matter to add it to the existing file.

[jagabo]

Usually all you have to do is set your system up correctly to decode 5.1 to 2.1. If you can hardly hear the dialog it's because you have the system set up for a center channel speaker which you don't have. Try playing the attached 5.1 AC3 file. If you don't hear "center" at about the same volume as "front left" and "front right" your speakers/sound card/player are set up incorrectly for downmixing 5.1 to 2.1.

[pandy]

First check TV settings - http://forum.doom9.org/showthread.php?t=170055 very similar topic - perhaps AVC, AVL or similar technology destroying audio by removing voice from audio.