Getting 5.1 audio from an old Home Theater System

[Shayan779]

Hey guys, so I have this old home theater, Samsung HT-TX 25 Home Theater, it doesn't support Audio Optical nor HDMI connections. But my main argue is that it does support DTS and Dolby Digital (and it hast a dolby pro logic 2 mod too which is not my concern here). The only input connections are the old RCA analogue connections which i can't get any kind of surround sound. Now, i don't want any kind of video, i'm gonna connect my laptop to the T.V. via HDMI. I only want the sound of the movie to be 5.1 (and i have all of the audio formats, DTS, DD, AAC and all of them 5.1). So even if i can get the audio separated from the movie itself, i can sync my movie in the laptop with the idea no problem. The point is how can i get the surround audio? The system support USB and DVD, i attached a file about the supported usb files in the manual. I tried converting one movie to a suitable format, from MKV to .AVI Xvid. My home theater could read the video, but it couldn't read the audio. The movie's source audio was AC3 (which my system should support) 5.1 with correct sampling frequencies and bitrates. I converted it to Xvid with Freemake Video Converter, but my system didn't read the audio, therefore, the movie didn't have any kind of audio, which was what i wanted. So what are the other ways for me to get a surround audio? How can i get it? I don't know anything about DVD format or it's conversion.
And by the way, can i use my speakers with another system? I mean, do all these kind of system use the same port for speakers so that i can keep my speakers and just buy a stock receiver?

https/ibb.co/eacyaa

 

[ssddx]

if the htib lacks hdmi, optical or 6x analog inputs then it also lacks surround sound input. even if it had optical or hdmi it is not guaranteed to be 5.1 input compatible. if it only has red/white rca inputs then it is a stereo input

chances are you have 2.0 input only and need to fake surround with dolby pro logic.

true surround is likely only if you use the included dvd player.

sucks, but this is commonplace with cheap htib units.

 

[madmatt30]

^ notvso much the fact bits cheap - rather its old , most all in ones have mkv playback via USB/disk & support 5.1dolby.
As you said this one doesn't.

 

[Shayan779]

if the htib lacks hdmi, optical or 6x analog inputs then it also lacks surround sound input. even if it had optical or hdmi it is not guaranteed to be 5.1 input compatible. if it only has red/white rca inputs then it is a stereo input

chances are you have 2.0 input only and need to fake surround with dolby pro logic.

true surround is likely only if you use the included dvd player.

sucks, but this is commonplace with cheap htib units.

I know this but the system can play DTS and Dolby Digital. I don't need any of them if I use the receiver itself, so i'm trying to find a way to use the receiver and I found one. I think if I convert my movies into the supported formats I can get surround audio (i don't care about video, i will get it by laptop HDMI to TV, and just sync it with the audio of home theater). I've done it with Freemake Video Converter and Any Video Converter but both of them convert something wrong with the audio.