Editorial: DVD, the X-Curve and Dirty Little Secrets (1 Viewer)

[Dan Ramer]

I had a handy reference on file. Have a look at this paper.
An excerpt: “Also, when heard over a modern flat loudspeaker in a small room, program material balanced on an X curve monitor sounds overly bright. That's because the original experiment that set the curve was made many years ago, without the frequency range available from today's components. This is not too important because, so long as everyone agrees to use the same curve, then the response sounds the same to the mixer on the dubbing stage as to the audience member in any auditorium. Interchangeability of X curve material with home video can be handled with a simple re-equalization.”
Hope this helps,
Dan

 

[Vince Maskeeper]

This is the completely wrong way of looking at this, since you don't setup your home system to be like the theatrical system. First, of course, is the X-curve issue. If you're looking for intent of the theatrical soundtrack, by playing it back on your speakers which are not rolled off on the top end, you are getting more upper freq than the person who mixed it intended. You are not getting the "theatrical" sound, as it would have sounded completely different in the theater due to the X-curve. It's not being watered down, quite the opposite in fact.
Secondly, theatrical surround speaker level runs 3db different from the mains, and mixes are created with this monitoring config- so when played on a even balanced system (as is HT config), again the surrounds would be 3db off from intent.
So, unless you decide to completely change how your home system is configured and calibrated, then you are actually the one modifying the soundtrack from the theatrical presentation. The people like Mi Casa are simply trying to make it match the standard for HT vs the different standards for Theatrical.
-Vince

 

[Daryl L]

Dan Ramer

It does help to be a reviewer.

LOL appears so and I thank you for for commitment. Can anyone get in on it. LOL just kiddin. Unfortunately being paralized from neck down I don't get out to movie theaters and by the time I rent or buy a dvd everyones already seen it and half of those people have already done reviews.
And here's another link to an article on the X-Curve if anyones interested.
Link Removed
I also replied back to Robert Margouleff's e-mail thanking him for the his prompt response, information and his efforts at de-emphasizing the X-curve and I included the link to this topic. Maybe it will help get this interest spread out a little more to the entertainment industry. I also mentioned the unused DD flag Vince brought up.

 

[Dan Ramer]

Daryl,

Good link and very timely, too.

Dan

 

[Wayne Bundrick]

I understand the technical background. I know about X-Curve, the 3 dB difference in the rear channels vs. cinema standards, the LFE +10 dB reference level, and I'm among the apparent few who, like Vince, understand that Dialog Normalization is a Good Thing.

This remixing and reequalizing of the soundtrack for DVD is analogous to the mastering step of making audio CDs, and the thought makes me cringe. I have no fondness for the state of the art of mastering CDs over the past 10 years because the quality of CDs has gone to hell on the proverbial road that is paved with good intentions. Pardon me for not having any faith but I think we're going to see the same intentions lead DVDs down the same road.

I could accept the practice of removing the X-Curve from DVD soundtracks, if that was all that they're doing. But that's not all they're doing. Read the articles at the Margouleff web site and see if they don't give cause for alarm.

From the 12/99 Widescreen Review article, Margouleff and Biles (and New Line's Jesse Torres) interviewed by Gary Reber:

"Films are all originally mixed for theatrical release" Margouleff explains, "which means for a large hall where the person in the last row of the movie house needs to be able to hear the dialogue. The surround aspect is not emphasized as much as for home theatre. They don't like to put a lot of stuff in the rears. They call it the 'exit light' effect, because people always face where the sound is coming from, and if there's something coming at them from behind they will turn over their shoulders to see it."

The purpose of the mastering job for DVD is to translate the theatrical mix into the home environment. "When you take that soundtrack and you want to put it into a home theatre," Margouleff says, "To serve the film best, the soundtrack must be rebalanced. In a home theatre you are only going to be playing for a few people, so you can work the rears up more and define the space. DVD is its own animal, and requires that the content be designed to fit the format."

Arrrgh.

 

[Dan Ramer]

Wayne,

I understand your concern, but what would you suggest the industry do? Soundtracks mixed for the large acoustic volume of a motion picture theater and its loudspeakers are just plain wrong for the small volume of a home theater and its type of loudspeakers.

And please consider that without room equalization (preferably parametric as opposed to graphic - parametric filters have less ringing and better transient response) the sound in your listening environment suffers from aberrations in frequency response caused by the nulls and peaks of acoustic standing waves. And the room's reverberation times at various frequencies will affect perceived frequency response, intelligibility, and spatial imaging. Are you willing to manipulate the reflective, diffusive, and absorptive properties of your room? Are you willing to invest in seven parametric equalizers and adjust them with a pink noise source and a third-octave band analyzer? If not, the differences between a DVD's de-emphasized and re-balanced soundtrack and the motion picture experience is very likely less than the differences caused by your room acoustics.

Dan

 

[Ted Lee]

sorry guys, but i've been trying to understand this and am not quite sure i get it.

it sounds like the a soundtrack is mixed "hot" (+3db) by the studio, and that this could be a problem except that it's deemphasized by the same amount...so in essence we're zeroing out the effect?

if someone could explain this in layman's terms i would appreciate it.

 

[Dan Ramer]

Ted,

Please read the links found within this thread; they will do a better job of explaining the X-Curve. I'll try to summarize as simply as I can.

Mixing stages where motion picture soundtracks are prepared are usually set up to mimic the standard frequency response of motion picture theaters. That standard electroacoustic response (the X-Curve) attenuates high frequencies by rolling them off (reducing their amplitude) by 3 dB per octave starting from 2 KHz. When the sound mixer sitting at his console on the mixing stage compensates for that falling response, the higher frequencies in the soundtrack are exaggerated (or pre-emphasized). When you play back such a track at home, where the room is smaller and the system response is closer to flat, the audio sounds "hot" since the high frequencies are then too loud with respect to the lower frequencies. Re-equalization rolls off the response to restore tonal balance. This can be done by the DVD's sound contractor (Mi Casa's work for Blade, for example) or at home within your digital audio decoder.

The issue is that we almost never know whether the X-Curve has been de-emphasized on the DVD or not.

I hope this helps,

Dan

 

[Ted Lee]

ahh...that helped dan.
so, unless we know whether a dvd was adjusted we won't know whether to compensate by re-eq'ing.
hmmm...i do see the problem. great...another thing to obsess over!

 

[Daryl L]

Ted,
Here's another way to look at it. Think of the high frequency sounds as a baseball and the speed of the ball as the X-curve. Now lets say you sit about 25 to 30 feet from the screen. A man standing up at the screen throws the ball aiming over your head but at a speed so by the time the ball reaches you it will have dropped(frequencies lowered) low enough for you catch it directly infront of your face.
Now move to about 10 feet away(home theater estimated distance) from the screen. Have the man throw the ball exactly the same angle and speed. This time it's to high(sounds frequency hasnt lowered yet so it sounds bright) and flies over your head before dropping.
Now places like Mi Casa Multimedia and New Line Cinema(possibly others) will throw the ball slower(de-emphasize the X-curve) so the ball drops sooner so you can catch it at face level 10 feet from the screen instead of 25 or 30 feet(so sounds don't sound bright).
I hope I got that right and that it makes sence.

 

[Ted Lee]

thanks daryl - analogies like that help me out a lot. i'm much better understanding things when given to me in layman's terms!

 

[Jeff Kohn]

Wayne,

I understand and to some extent agree with your concerns. On the other hand, it could be argued Mi Casa must be doing something right given the praise that their soundtracks are getting: Blade II and LotR are both getting called the best DVD soundtrack to date by various people.

I would say that as long as they are concerned with reproducing the movie experience with accuracy and fidelity in mind, and they really know what they're doing, it's probably OK. The thing that would give me cause for concern would be if they started compressing the dynamic range or otherwise altering the sound in order to cater to J6P using TV speakers...

 

[Christian Dolan]

Wayne,
I had posted this link in another thread, but feel that it is relevant here:
http://www.surroundpro.com/2002/apr...s_5point1.shtml
Tom Holman talks about how sound reproduction doesn't scale down psychoacoustically;if something is mixed for a larger environment, it won't tranlate to a smaller one without re-mixing.Hope this helps.
-Christian