Is there any reason to keep the 2-channel audio in addition to the 5.1 Channel AC3?

[js]

Long time lurker on these boards, and have been using DVD Shrink extensively for a year or so (By the way, it's the absolute BEST free pie I've ever tasted!!). Finally signed up to post because I could not find an answer to this question in my searches.

When I backup a DVD larger than 4.34 GB, my first step (as with everyone I suspect) is to remove languages I don't need, or audio tracks I don't want (say a director's commentary I'm not interested in). I also uncheck the DTS 5.1 track in favor of AC3 and higher video quality (realize this is a judgement call, so not looking to start a debate on that one :D )

Here's what I can't figure out though . . . if I am retaining the 5.1 channel audio, is there ANY need to keep the plain 2-channel audio? If I plan on using the backup disc on a laptop or headphones that don't feature 5.1, will the 5.1 track over 2 headphones or over my 2 tinny laptop speakers sound just like the 2-channel would (i.e. does it consolidate the 5.1 channels into the 2 available speakers?) or would I end up hearing, essentially, just the left and right and lose the dialogue channel and anything coded for the rear surround channels.

I've never actually gone into a DVD's menu and specifically selected the 2-channel soundtrack, even when I'm listening on headphones, so either it gets selected automatically (doubtful, I suppose) or the 5.1 sounds fine over 2 channels. If that's the case, then I have been wasting a couple of hundred MB on each of my backups with a superfluous audio track at the expense of my video quality.

Can someone help me understand this better?

Thanks!!

--Jason

[gircobain]

With proper configuration of your software dvd player, the 5.1 track gets downmixed to 2 channels
I believe the only advantage of a 2.0 track is it (perhaps) has a better mix for stereo speakers than the downmixed 5.1
Though I don't think it is anything much noticeable
Someone correct me if I'm wrong

[js]

Interesting . . . so gircobain, if you yourself regularly shrink DVDs to fit on DVD-Rs, do you eliminate the 2-channel audio? Are there others out there who have done so and can report back no troubles with watching their DVDs in a 2-channel environment?

Since I never go and select the 2-channel audio from the DVD menu, I suspect that this downsampling gircobain refers to is *exactly* what my laptop has been doing . . . I will go and experiment with both audio channels of a movie and see if I notice a difference over headphones, but I'd much prefer hearing from someone who's actually been watching their DVDs this way for awhile . . .

Thanks, I look forward to more info on this!!

--Jason

[Kedirekin]

Originally posted by js
I've never actually gone into a DVD's menu and specifically selected the 2-channel soundtrack, even when I'm listening on headphones, ... the 5.1 sounds fine over 2 channels

Precisely correct; you've been listening to 5.1 sound downmixed for stereo output all along. Virtually all stand-alone and software players are capable of downmixing, and you'd be hard pressed to hear a difference. Personally I think removing a redundant 2.0 soundtrack is a pretty harmless way to improve video quality (and I agree on removing DTS also - AC3 5.1 quality is ample for a backup).

[echooff]

Kedirekin has it right as far as i'm concerned. I only keep the 5.1 mix and never a problem with the audio on any player.

[js]

WOW, Thanks everyone for the information! I sure wish I'd asked this question at the *beginning* of my quest to backup my DVD collection, rather than now when I'm halfway through the process. :D

So, all this begs the question -- why do DVD manufacturers include the 2-channel track? Would anyone ever *want* to select that track over the default 5.1?

--Jason

[mrbass]

Do you check the 2 channel...usually it's just directories commentary. Rarely do you see it anymore as an alternate main sound track.

[sweetness]

Just to clarify if my receiver downmixes a 5.1 channel signal to stereo do i hear all the sounds? Is there anything lost in the downmixing?
I know people that are die hard DTS fans and others that say there is very little difference between DTS and DD5.1. i guess it's all in the taste.(i'm hungry now)

[gircobain]

Originally posted by sweetness
Just to clarify if my receiver downmixes a 5.1 channel signal to stereo do i hear all the sounds? Is there anything lost in the downmixing?
I know people that are die hard DTS fans and others that say there is very little difference between DTS and DD5.1. i guess it's all in the taste.(i'm hungry now)
It all depends on your receiver config. But why would you config your receiver to downmix 5.1 to stereo? :confused:

[sweetness]

I'm the guy that would spends $2000 or more on speakers but i would buy a set every year. right now i have right and left channels and a centre channel.

[js]

Originally posted by mrbass
Do you check the 2 channel...usually it's just directories commentary. Rarely do you see it anymore as an alternate main sound track.

Yes, I listen to them in DVD Shrink, and there seem to be (frequently) 2 or more English 2-channel tracks, one of which is plain dialogue and one or more of which are various commentary tracks. In the past, I've been willing to drop a commentary track to save space, but based on this thread it sounds like I'd be better off dropping the plain track, or perhaps both.

--Jason

[The_Flash]

If I choose to keep the DTS track I often keep the 2 channel audio as well. This way people who may borrow my backup that don't have a DTS receiver will still be able to watch the film, and the space required by the 2 channel track is almost negligible (compared to the 5.1 AC3 anyway).

[js]

Originally posted by The_Flash
If I choose to keep the DTS track I often keep the 2 channel audio as well. This way people who may borrow my backup that don't have a DTS receiver will still be able to watch the film, and the space required by the 2 channel track is almost negligible (compared to the 5.1 AC3 anyway).

I never keep the DTS track since I don't have a DTS receiver, but are you saying that a DTS 5.1 won't downsample to stereo the same way the AC3 will? So are you saying that you'd need to keep something else for the sake of a non-DTS-enabled viewer, and that the 2-channel audio is a better pick than the AC3 5.1?

[valnar]

So, all this begs the question -- why do DVD manufacturers include the 2-channel track?

That one I can answer.... for some of the DVD's.

In many cases, the 2-channel track will be from the original movie format. DD 5.1 may be a bastardized version somebody developed after the movie was released. Remember, many movies from the 80's and earlier only had stereo (or mono), so the purists will want that audio track intact. A DD5.1 track is often remixed just for the DVD release so we can enjoy surround sound, but we never heard it that way in the theater 20 years ago.

In that sense, think of the DD5.1 track as a "remaster" of the 2 channel track.

-Robert

[echooff]

I never keep the DTS track since I don't have a DTS receiver, but are you saying that a DTS 5.1 won't downsample to stereo the same way the AC3 will? So are you saying that you'd need to keep something else for the sake of a non-DTS-enabled viewer, and that the 2-channel audio is a better pick than the AC3 5.1?


If you have a DTS reciever you don't need to downsample since you will enjoy the DTS more than 2 channel dolby audio. The 2 channel is for the poor unfortunates who can't enjoy DTS because of lack of a DTS capable receiver.


Perfered audio on a backup. This is strickly my preference for my listening pleasure.

1. DTS
2. AC3 5.1
3. 2 channel

[js]

Originally posted by echooff
If you have a DTS reciever you don't need to downsample since you will enjoy the DTS more than 2 channel dolby audio. The 2 channel is for the poor unfortunates who can't enjoy DTS because of lack of a DTS capable receiver.


Perfered audio on a backup. This is strickly my preference for my listening pleasure.

1. DTS
2. AC3 5.1
3. 2 channel

:D Well for now I am one of those poor unfortunates (though my father has finally broken down and installed the home theater he'd always wanted so last night I took my family up to watch a movie in grandpa's DTS movie theater).

But what I meant to ask is this:

a 2-channel stereo recveiver CAN downsample 5.1 AC3 to be heard over 2 speakers, can it NOT do the same to a DTS 5.1 track? (and thus that's why you have to keep both?

--Jason

[echooff]

a 2-channel stereo recveiver CAN downsample 5.1 AC3 to be heard over 2 speakers, can it NOT do the same to a DTS 5.1 track? (and thus that's why you have to keep both?

No it can't. A ac3 5.1 is still 16 bit audio at 384-448 kbps , so the audio decoder is still dealing in the same range. DTS is 24 bit audio at 768-1536kbps. (I seem to remember reading it can be 32 bit also, but could be wrong) So... the decoderwould have to completely re-encode on the fly.

[jfcarbel]

Is it the receiver that downmixes the 5.1 or the DVD Player?

Because if it is only the receiver that does this, then the other reason for having a 2.0 soundtrack, that is for people hooking up a DVD player directly to a TV without a receiver.

If you leave only the 5.1 track and borrow your DVDs to a person that only has a DVD Player hooked to a TV, then they hear nothing. I know this from experience.

[echooff]

A dolby 5.1 capable dvd player. I am pretty sure all of the new models support it but I know some of the older ones either did not or did a poor job of it. Most of the newer players support DTS also, but not all. IMHO 5.1 channel sound is wasted if you don't have a system capable of playing it. Most tv's do not come with surround speakers. My dvd player/cd player supports ac3 5.1 and DTS. the 600 watt surround output really sounds good on a properly encoded audio file. My older stero didn't support either. The difference is phenominal. I finally came up with the $300.00 for my present system. It has made me a happy camper. If you do not have a capable system and will not be able to afford one in the near future go for the 2.0 file.

[et415]

I'm a newbie who just started using DVD Decrypter and AutoGK. I recently created a file with AC6channel and AC2channel (Director's Commentary). I use Windows Media Player 9. When I play back the avi file, it plays with the Directors Commentary always on. I can't figure a way to turn it off. Is there a way to do this? Is there another software playback device that can handle xvid?

[rayvt]

Ya know, even if you only have a 2-channel stereo *now*, you might very well upgrade to a DTS receiver/amp in the future. Prices are dropping all the time--or maybe you'll have to come up with a semi-exensive gift for somebody to give you. ;-)

If you don't burn the DTS onto your DVD, you'll never have it even if later on you decide that you want/need it.

Anyway, if you really want to keep the best video quality, use DVD-RB instead of DVDShrink.

[js]

It's obviously all about personal preference, but so far I don't think anyone is talking about keeping *just* the 2-channel stereo (though I'd need to go back and re-read all the posts). For the most part we're talking about dumping the 2-channel and the 5.1 DTS and keeping the 5.1 AC3. In general, the 5.1 AC3 seems to take about half the space of a 5.1 DTS, so I can improve my video quality from, say, 60% to 70% by keeping AC3 instead of DTS. Actually, if one does not currently own a DTS receiver, then you'd really need to keep BOTH AC3 and DTS, so we're talking about boosting video quality by, perhaps, 700 MB, say from 60% to 80%.

To me, then, this seems like a reasonable risk. I know I can always use the AC3 5.1 track, even on a DTS receiver, so I'm giving up the future chance to possibly listen to the DTS track (whose quality improvement I may or may not be capable of perceiving) in exchange for a video improvement on every single viewing which I already know I am capable of perceiving.

Again, this is a completely personal preference I realize, and a true audiophile (which I don't claim to be :D ) would just as likely consider it a no-brainer to accept lossier video in exchange for purer audio. I'm just laying out my rationale.

Then again, I'm just biding my time till DVD-9's go on sale for $.60 apiece at Office Depot ;-)

--Jason

[et415]

Rayvt,

I actually have a 5.1 DD a/v receiver. My PC is connected to it via a TOSLINK connection. But for some reason, I can't hear the 5.1ac track. When I tried using another software tool before, I remember they said something about needing a filter of some sort to hear the 5.1 digital track. Should I be able to hear the 5.1ac track out of the box? Or do I need something additional?

Thanks...

[echooff]

I'm with you js. I have a DTS capable reciever and still keep the ac3 5.1 only. I have 4 dvd players but only one supports DTS. Besides these are onjly backups to keep my children from destroying the originals. When I want DTS i'll either make myself a new backup or play the original.

et415: you need either a dvd software player or a a filter if you are playing it from your computer

[js]

Just an interesting follow-up (well interesting to me anyhow). I just got the new season of MASH (they're up to Season 6) and was making backups of the 3 discs. I noticed that there are 2 English tracks on them (plus French and Spanish). Well I previewed both English tracks and couldn't hear any difference, was getting a bit confused.

So I went to look at the audio menu and see what their explanation was. I don't know how many shows do this, but the very thoughtful producers of the MASH DVDs included one English Track as it played on TV and another without the canned "laugh track". It's funny, but my wife has always hated the canned laughter in TV shows, so now I can watch MASH with her and *we* get to decide when to laugh :D

I thought it was an excellent idea for an additional track, especially on a disc which is not likely to have an elaborate commentary or high-quality audio, simply because it's so old . . .

--Jason

[The_Flash]

That's a great idea. The canned laugh track on tv shows has always annoyed me as well. Thankfully they don't insert people crying when a scene is dramatic, or an "oh shit!" during a plot twist.

[Blogas]

It's a little bit different story in music DVD's. Sometimes you can have 2 channel pcm stereo soundtrack, which seems to be uncompressed at all and is very hudge. I prefer allways to remove it while shrinking and stick to DD51 or DTS. BTW there is a very notecible difference in sound quality between DD and DTS in music DVD's. So i prefer to keep DTS in most cases. Music is for listening, and not for viewing i think :)

[et415]

Originally posted by The_Flash
Thankfully they don't insert ... an "oh shit!" during a plot twist.

Don't you remember "I Love Lucy"? Whenever Lucy was about to get into trouble, the laugh track always had a "oh, oh..."

[The_Flash]

Never watched much of Lucy. Can't say that I ever found that show to my liking. But that is interesting, and I'm sure annoying.

[js]

Ever since getting the helpful info shared by the folks in this thread, I've been keeping my eyes peeled for a movie that had this type of situation -- a 5.1 channel AC3 as well as a 2-channel AC3.

Came across one today -- The Sum of All Fears. You can confirm this here:

Amazon listing (http://www.amazon.com/exec/obidos/tg/detail/-/B00005JL8F/?v=glance&s=dvd&vi=tech-info)

Where under technical info it shows:

Available Audio Tracks: English (Dolby Digital 5.1), English (Dolby Digital 2.0 Surround), French.

There are 2 director commentaries, and a total of 5 audio tracks.

1. 5.2 channel movie soundtrack
2. 2-channel dolby surround movie soundtrack
3. 2-channel French
4. 1st director commentary
5. 2nd director commentary

By eliminating tracks 2 and 3, the necessary compression level dropped by more than 2 percentage points.

Thanks again to everyone for all their help here!

--Jason