I don't know alot about audio, but when I am ripping a movie I am usually given the choice to include 5.1 and 2 audio. I usually just include 5.1 and not 2.

My question is will the audio quality suffer, be the same, be better when listening to 5.1 dobly on just a tv, not audio system hooked up?

I am really confused about which audio I should include, and I dont want to include both because it takes up too much disc space.

Thanks.

Standard tv will have either 1 main speaker or 2 speakers being 1 on each side..

Unless you have your tv going thru a receiver with a 5.1 or more speaker setup,
your not going to hear nothing more than stereo or what some tv manufacturers call simulated surround sound.

A movie is edited or mixed so that each speaker in a standard 5.1 system has it's own audio track and without getting too much into it I would save the compression and just use 2.0 audio.

If you are pretty sure that you will only play your backup discs with audio output via TV speakers, yes you should stick to 2.0 so as to minimise the video compression. Otherwise, I would suggest you choose 5.1 just in case you may play the discs thro an AV receiver (say in a friend's house), but you are quite right, you don't need to include both audio channels

Dolby Digital 5.1. Has much more audio data, it stores data in different channels. For example if you have a Dolby Digital setup in your home (usually you would be connected to an A/V Receiver with a Coaxial or TOSLINK Optical Cable)...and let's say you're watching a Dolby Digital movie and explosion occurs behind, that sound would be positioned BEHIND you. If it was somewhere else to the center... front right.. front left.. etc... It positions audio where it should be.

The Stereo 2.0 setup just has 2 channel audio information (left/right), most people probably have this setup, the amount of data it takes on the DISC compared to 5.1 is minimal.

If you leave 2.0 out and leave only 5.1, you might not be able to hear any audio unless you have the 5.1 digital setup. 2.0 would be the safest most compatible way to go.

But be warned! I used to do this (remove the 5.1 tracks)...a few years later I went with a FULL 5.1 speaker setup in my home, now those old movies suck to watch without the full 5.1 effects. I just use Double Layer discs now and keep all audio tracks (well except for multiple language tracks..)

I believe all DVD players can downmix the 5.1 track into stereo if you setup the player properly. I don't think you need to worry about not hearing any sound at all. Note that most commercially pressed disc nowadays often contain only the DD5.1 tracks without the corresponding 2.0.

Since we are on the subject let me run something by..
I have a Harmon-Kardon 5.1 a/v receiver..

I have held back from upgrading to 6.1 or 7.1 for 2 reasons.

[1] I have not come across any movies that are mastered in 6.1 or 7.1.
[2]
I am under the impression that sound from the extra rear[middle] speaker for 6.1 is basically the same sound that is mastered for the the 2 rear speakers and thus passing thru the middle speaker in order to create what appears to be 3 seperate rear audio tracks but really only 2.

Same for 7.1..
the extra side speakers,[ middle left and right] are doing the same thing..
simulating more as a pass thru as opposed to a true seperate 7 speaker mix..

Am I correct in assuming it's more a marketing thing or is it time to go 6 or 7.1?

Assuming you have a room to handle it, 6.1 or 7.1 sound is amazing. There are many movies that contain Dolby EX or DTS Discrete sound. Even the ones that do not sound better with my HK 7.1 setup.

Now, if you don't have a good room, it won't make any difference. A good room is one that has nearly as much space behind the seating as in front. You want to the surrounds on the sides and the rear(s) behind you (about the same distance as you are from the fronts).

Also, the new formats take full advantage of 7.1 setups (that is, HD-DVD and BluRay).

Check my setup in the home theater link in my signature. I've upgraded most of it since this page was setup, but the speaker layout has not changed much.