Dolby Digital or DTS?

[drewface]

heh, i've noticed all your posts are usually quite lengthy, dread. thanks for all the info.

i got my system hooked up today at home and did a couple test runs with scenes from the lord of the rings (special extended edition), switching back and forth between DD and DTS. contrary to a comment you made in your post about DD tracks being played more quietly than DTS, i actually found the DTS to be softer (had to turn the volume up louder on the DTS mode to get the same perceived volume). i'm still undecided on which i prefer, although DTS did seem less harsh with the very high pitched effects like dragons shrieking and the like...

i think this is one of those things that everyone will have to experiment with and decide based on their personal preferences and the equipment they are using. i always used DD before today, but i'm gonna have to do some more comparisons before i make a final decision.

[Dread Pirate Robert]

That has got to be some of the best explaining I have read!

I'm glad it turned out so well, which is not always the case for me.

Robert, who are you and what do you do?

I'm not an audio expert and am still a neophyte at Hi-Fi audio, but codecs are right up my alley as a computer programmer. I've been involved in HT for a long time, although I've sort of disappeared over the past several years. I used to post as Robert Cook (my real name), although I go under a number of different user names now.

heh, i've noticed all your posts are usually quite lengthy, dread. thanks for all the info.

I know, it tends to drive people crazy after a while, actually. But enough about me....

i got my system hooked up today at home and did a couple test runs with scenes from the lord of the rings (special extended edition), switching back and forth between DD and DTS. contrary to a comment you made in your post about DD tracks being played more quietly than DTS, i actually found the DTS to be softer (had to turn the volume up louder on the DTS mode to get the same perceived volume).

Although I tried to cover as many practical points as I reasonably could, my post was mostly about the theory behind comparing these codecs, which assumed "all else being equal." If, for example, a more dynamic mix is used for DTS than DD, the dialogue and much of the rest of the soundtrack could be mixed at a lower level in the DTS master, which gives it more headroom to work with for especially bombastic effects, and consequently forces you to turn up the volume, even past where you'd have it for the less dynamic DD mix. This would especially be true if the DVD producer is knowledgeable and chooses to set the DD dialogue normalization to 0 dB attenuation, which an increasing number of them appear to be doing of late.

Obviously, this is a very complex issue, and one of my main points was that in cases like this, while DD at 448 kb/s is capable of the same dynamic range and a similar level of quality as DTS at 754 kb/s, in the end, it's DTS that almost always gets the "better" mix. From this you can probably infer that for most practical purposes, I consider DTS a marketing tool and a waste of space at 754 kb/s (just encode the best mix in DD and be done with it!), although it's great at 1509 kb/s when space and bandwidth allow. This doesn't change the fact that the DTS track should almost always be selected in order to hear the superior mix, of course.

i'm still undecided on which i prefer, although DTS did seem less harsh with the very high pitched effects like dragons shrieking and the like...

Well, this mostly depends on how the soundtracks are mixed, but DTS does begin to roll off the treble at 15 kHz, while DD at 448 kb/s is pretty flat up to 20 kHz. I can't say whether the latter makes a difference in this case, since most people can't hear much past 15 kHz in any case, but there are differences in how the codecs handle certain sounds, and some people may slightly prefer either to the other. At least on paper, DD at 448 kb/s is relatively well supplied with bits most of the time, while DTS is starving at 754 kb/s due to the differences in coding. While it's quite possible that many if not most people would prefer the changes (based on a perceptual model of human hearing) that DTS is forced to make to the sound at half-bitrate, DD is theoretically and measurably making fewer changes.

i think this is one of those things that everyone will have to experiment with and decide based on their personal preferences and the equipment they are using. i always used DD before today, but i'm gonna have to do some more comparisons before i make a final decision.

That's good advice in general, although I'm pretty sure that most people who have home theater surround systems with subwoofers and enjoy the sometimes ridiculous dynamics of movie soundtracks would prefer the DTS tracks in virtually every case, if for no other reason than that better mixes are often used and they are never compromised for limited equipment, as DD mixes often are.

[clarke68]

Very helpful and informative post...with a little tidying up, you could sell that one of the home theater magazines for $1/word!

Quick question: how can I tell in what bitrate my DVD soundtracks are encoded? I've never seen it printed on the box, is there a website somewhere that puts out DVD publisher inside info?

Thanks!

[Dread Pirate Robert]

Very helpful and informative post...with a little tidying up, you could sell that one of the home theater magazines for $1/word!

Thanks for the kind words. Hmmm...just thinking about that second thing you said....

Quick question: how can I tell in what bitrate my DVD soundtracks are encoded? I've never seen it printed on the box,

My DVD player happens to show the bitrate on one of its on-screen displays, and some receivers may do the same, so you'll want to consult your user manuals to see whether this feature is available. If it isn't, then there are other ways to tell that should not be discussed on public forums.

is there a website somewhere that puts out DVD publisher inside info?

The following page has a fairly comprehensive list of DTS bitrates:

http://www.spannerworks.net/reference/10_6a.asp

Most 5.1 DD soundtracks have a bitrate of 448 kb/s, which has been the case for a long time now, but 384 kb/s doesn't sound all that different most of the time, so it's not as significant as 1509 kb/s versus 754 kb/s for DTS, and I couldn't find any lists of DD bitrates. DD is rarely encoded with a bitrate lower than 384 kb/s, although I have seen 256 kb/s on some documentary titles.