I been doing trials and error on my behalf through research on google. Some methods I used was like demuxing the audio and video.. the process was too complicated and tedious (yes I did it though) but it came out corrupted or wrong- even after converting mkv to avi with no sound and stripping the audio (ac3 5.1) separately. I then muxed them together with AVIMux_GUI. Other programs I am aware does not support muxing and saving it to avi container nor even accept avi as a whole. I tried some programs that claimed it did like "avidemux 2.6" and all it did was encode the video mkv to avi.. it did nothing as far as making it true .avi. And some of my other media players would confirm this since it reads avi's and this one (or many I made) came out corrupted but played well on my PC. I'm using mkv video files mainly with 5.1 channels. I am also dealing with ac3 right now but, wondering if its possible to do this with dts. I have some videos on my computer that is avi and has 5.1 channels and plays well on my external media players. But I don't know how that person did it.. since its from an outside source. Any help guys? I know its possible but I suppose its probably more complicated than what I did.. the only other alternative is to convert the videos I have with 5.1 channels to mp4. Majority of video converters accept output to ac3 with the exception of using mp4 only. I'm trying to avoid mpeg and mkv. Thus converting mkv (for example) to avi but retain the 5.1 audio(ac3/dts).