why do some movies both 2.0 and 5.1?
 

if a movie has a 5.1 soundtrack, why do some dvd's also include 2.0?

I would guess that the 2.0 soundtrack works better with equipment that only has Pro Logic.

to raise the price up $10? think why some movies have both 5.1 & 2.0 is because some people don't like the noice coming from the back speakers that give it the surround sound effect, personally i love 5.1 and hate when per say my favorite tv show has only a 2.0 track.

hell the TCM: The begginning had a 5.1 & DTS 6.1.
i think all dvds exept for the ones were the content wasn't original recorded in 5.1 of course.

5.1 is the best!

Wow, that was an incoherent post.

The reason some discs have a 2.0 track is that not everyone has or even wants a surround sound setup. Although DVD players will downmix a 5.1 audio track to 2.0, a dedicated 2.0 track that was mixed by a human being for that purpose will sound better.

Also many times, with older movies, the original soundtrack was only stereo (or mono) and many movie purists will want that as an option.

Precisely.

does anyone know all the films that were first to use all the sound formats?
i know batman returns was the first 5.1 and jurassic park was the first dts in cinemas. and i think the region 1 austin powers the spy... was the first dvd release to have a rear centre channel. though i dont think the cover mentioned it.

exactly!
the better question is why the hell wouldn't some DVD's have a 2.0 track at all. some people don't care about sound. i don't understand it, but to each his own.

Actually it wasn't... It was just the "official" launch title of the format nationwide.

Star Trek VI: The Undiscovered Country was the first 5.1 Dolby Digital film rolled out in limited quantities as a test... I think there was one other test film before Batman, but I can't remember what it was.

As for the first 5.1 film... There were many 70MM prints in 5.1 before Dolby Digital or DTS came one the scene, in the eighties.

fitprod

how can a human mix sound better than a algorithm splitting a surround track into left and right?

Yep.

Oh. My. God. Audiomixer, you wanna take this? Well, in case he never sees this...

Done properly, a 5.1 mix should mix down into an acceptable stereo mix. Still, it's much better to have a completely separate 2.0 mix available, since even though they may mix imperceptibly into the stereo soundfield, you don't always want to have surround effects playing through the main speakers. In the same way, you often can't just drop the surround channels, because some audio that's assigned to the surround channels is important, and shouldn't be arbitrarily left out just because rear speakers aren't available.

Just ask Seth Brundle :D

yes "oh my god" a person doesn't know the difference between automatic downmixing and manual downmixing.


give me an example of what you're talking about (missle, helicopter, etc)

1) how is it supposed to sound in 5.1
2) how would it incorrectly sound from automatic 2.0 downmixing
3) how is it supposed to properly sound in 2.0

If you're asking me why you should care about separate 5.1 and 2.0 soundtracks, forget it. I'm tired of going into great detail explaining how and why things are done, only to have someone reply "big deal, I don't care about that" and perceive themselves as winning some kind of argument.

If you really want to know why this is done, it's pretty simple. I actually explained this already, and part of it is that not everything in the surround channels is a missile or a helicopter. In other words, it seems simple to you because you're oversimplifying things.

Conversely, I may actually be making things more complicated, or at least giving you more detail than you need. The simple fact that surround information is mixed out-of-phase with the main channels in a two-channel surround track, and therefore folks who try to play a 5.1 stream through a non-5.1 system will often just get stereo should really be enough. It's the same reason you often find DTS and Dolby Digital tracks on the same disc -- if they're both 5.1, what's the point? Well, they're decoded differently, so having two separate tracks covers a wider range of equipment that someone might have in their home.

However, to answer your question more directly, re-read what I wrote in my last reply. Sometimes you don't want to just lump all the surround stuff in with the main channels, and you also don't want to just drop it altogether. The same can be said of LFE material -- it might be fine for a dedicated subwoofer, but you don't want to burden smaller speakers with it, but at the same time you don't want to just drop it.

You don't really seem too technically inclined, so I guess the short answer is, "technical reasons". The best way you can illustrate it to yourself is to find a 5.1 surround system and start disconnecting speakers to turn off certain channels. Of course like I said if you just "don't care", there's not much I can say to convince you that important stuff will be lost if the surround channels are just dropped, and things will start getting muddy if everything is just mixed into the main channels, so what chance do I have. Just trust me that there are a LOT of things you don't particularly happen to care about that are important when it comes to creating DVDs. Also trust me when I tell you that those alternate soundtracks aren't using enough disc space to cut into the video bitrate possible on the disc. If you sit down and calculate the space required for a 2-channel Dolby surround track, then spread those bits over a 2-hour program, it doesn't free up enough space to raise the video bitrate much at all. On a DVD, <b>video</b> is what cuts into the bit budget -- extra audio tracks aren't nearly as much of a concern.

The bottom line is that yes, a properly-mixed 5.1 soundtrack should really mix down to stereo okay. Thing is, you can't just add A and B together arbitrarily and expect them to sound like C. Think about color. If you're trying to achieve a certain shade of orange with stage lights and gels, and you get it perfect using four lights and a few red and yellow gels, you can't necessarily expect that exact shade of orange if you go down to two lights and just place both gels from the front and back lights on the front lights. It simply doesn't work that way. Of course if all you want is "orange", you may be satisfied with anything that looks like red and yellow are mixed together. The fact is that sound designers want you to hear certain things, and abritrarily mixing six channels down to two doesn't always do the job, nor does only playing two channels of a six-channel mix.

I apologize if I haven't made it any clearer, but if you're only after hearing helicopters and missiles fly around the room, I don't think you're really missing anything important. Maybe it really is bliss after all. ;)

Well, I guess if I don't directly address your three points, I'll get all kinds of flamed, so I'll try, based on the helicopter example:

1) In a 5.1 mix, the sound of the helicopter would be distributed around at least 5 of the channels -- each speaker except center would have some engine noise in it, and the subwoofer would have a lot of LFE. You'll have echoes off nearby buildings, mountains, etc. that will add to the ambience of the scene and help create the illusion that the helicopter is in the center of your living room.

2) Automatic downmixing is like taking a 3D image and squashing it flat. Worse yet, things in the surround channels won't make sense in the front channels. Those echos that made it really sound like the helicopter was in the middle of your living room don't provide the same effect if they're all coming at you from the front.

3) The manual creation of a dedicated 2-channel mix is like looking at a 3D object from one angle and taking a picture of it. It involves just making the helicopter sound like it's in the middle. You lose the dimension of depth, but still having stereo means you still have some indication of the location of the helicopter. You get rid of all the surround effects that will only make the mix sound muddy (because if they're not coming from the right place you don't need them), and you can add in stuff that was in other channels that is still important to the mix, like the LFE that would normally be routed to the subwoofer, although not as much, because most stereo speakers can't handle as much bass as a subwoofer.

There you go, hope that clears it up. I have no interest in whether you "care" about any of that or not, or whether you'd rather just have better picture than all those different soundtracks, I'm just telling you <b>why</b> automatic downmixing isn't always good enough. Even if you don't give a rat's ass about any of it, filmmakers and some fans most certainly do, and as I said before, it's not hurting your picture quality nearly as much as you might think.

rotfl

For years, all I had was 2 channel stereo to play DVDs. I preferred the 2.0 track to the downmixed 5.1, mainly because a downmixed 5.1 track compresses the dynamic range too much, and sometimes muddles (?) a few detailed sounds.

At the time, when I played a DVD that didn't have a 2.0 track ("The Perfect Storm", "Heat") I obviously couldn't compare.

The best examples of this I had at that time were "Independence Day" and the original non-anamorphic "Titanic" DVD. For ID4, the destruction sequence is goes from very quiet to LOUD as hell, and the 2.0 track reflects that. In the downmixed 5.1 track, it's all more-or-less the same volume. When I finally got 5.1 capability, I noticed that the range of the discrete surround sound had the same range of volume as the 2.0 track.

Thanks!

personally (& hopefully this isn't incoherent to you) i think all dvds (exept for the once that the film wasn't originally recorded in 5.1) should include both options, to many of them don't.

Thought I heard many years ago that the DVD standard required a mono or stereo mix always be present, in case the player couldn't down-convert. Maybe that used to be the case or maybe I heard it from an unreliable source. Haven't found any documentation to prove it.

...
 

why do dvds have sound at all? i just like to watch the moving pictures!

Good call.

Moving pictures? Fuck that. I just have a DVD player hooked up for the soothing hum it makes. I don't even own a TV.

that's because your dvd collection is porn.

Not sure what you're laughing at, but sure, I did go right ahead and explain it to him in great detail. I wasn't really saying that I'm tired of doing that, I'm just tired of having people respond to my detailed explanations with stuff like "So? I don't give a rat's ass about that kind of stuff, so they shouldn't keep doing it." A lot of people here seem to think that if it's not something they personally consider important, no effort should be "wasted" on it at all.

FWIW, I think Rubix and Mopower get exactly what I'm saying, and even if they're just poking fun at me, they've obviously seen the same kinds of posts I'm complaining about.

I'm not exactly sitting on a pile of documentation either, so I also could be mistaken, but I think the requirement was that players had to be able to downmix to stereo, rather than discs having to have a stereo soundtrack. There are of course other requirements such as discs having an AC3 stream available if they're for the U.S. market, or PCM being required in the UK (or was it MPEG... don't remember).

Actually, DVDs are required to have either an AC3 (Dolby Digital) track or a PCM track. And I'm pretty sure this applies to the DVD standard worldwide, not just in Region 1.

Yeah, it's a question of having at least one track of a particular type available, i.e. at least one or the other. Come to think of it, it may just have been that in the U.S., most manufacturers included an AC3 track, and in the UK, they went with PCM more often. In other words, it's probably more common to find a DVD with PCM audio in the UK than in the U.S., even though the global requirement is just to have one or the other at the minimum.

That certainly would make more sense.