Serving Two Masters

Sidebars
Bass Management Low-Down
The Sony Setup
DVD Remix at Zaentz

Optimizing for DVD in a Film Mixing Environment

Maintaining the integrity of films now requires optimizing DVD soundfor home theater play.

Looking back two decades to the launch of the compact disc, it'seasy to forget how iffy the carrier's prospects were in the first fewyears. Players were too expensive for anyone other than“early-adopters,” and labels, smarting from a post-discoimplosion, weren't ready to spend much on production for a format whosesales appeal was still unknown. In that climate, many CD masters,particularly for catalog releases, were simply transferred from EQmasters that had been made during mastering sessions for LPs.Reflecting the response of mastering engineers to the characteristicsand limitations of an entirely different playback medium, the sound ofthese early releases often falls short of the CD's potential.

When DVD-Video came along, many of the same factors came into play.In the DVD scenario, the role played by the EQ master in the recordindustry was played instead by the theatrical print master. Often theculmination of weeks or months of work, the theatrical print masterembodies the production team's judgment of how a film should sound whenexhibited in a theater. At first, it seemed safe to assume that DVD,given its digital audio capabilities, could adequately convey thissound to the home theater viewer. So once again, a source optimized forone medium was often simply transferred straight across to provideaudio for another. And once again this expedient proved less thansatisfactory, this time because the theatrical and home theaterlistening environments are such different worlds.

With DVD now firmly established, it's become increasingly common forfilms to undergo a separate remix to optimize the sound for hometheater playback. “If the job is done well, the sound translatesto the home theater environment as well as it does to the bigtheatrical environment,” says Jerry Steckling, technical officerat Skywalker Sound in Marin County, Calif. “The filmmaker satdown and said, ‘That's my movie,’ on those big theatricalspeakers, so the whole job in making the DVD is to try to give thatexperience on small speakers.”

Home theater systems, however, are not only different fromtheatrical sound systems but also far more varied. That can make itdifficult for film mixers to tailor their remixes for DVD with the samelevel of confidence they are used to from their theatrical work. And itcreates a challenge as well for technical staff, whose goal is to setup a monitoring environment that supports mixing for the whole spectrumof home theater environments.

The starting point when optimizing sound for any delivery platformis the question, “What's it going to be played back on?”When the target listening environment is home theater, that's not aneasy question to answer. “There's a big rainbow of things goingon,” says Brian Vessa, technical audio supervisor in thepostproduction services department of Sony Pictures Entertainment inCulver City, Calif. “Some people just took their hi-fi speakersand built out from there. Other people went the opposite direction andwent to the Good Guys and bought the little tiny speakers all around ora Bose system. You've got apples and oranges there. There's no standardin home theater.”

Of course, THX has tried to establish a standard through itscertification programs, but the reality is that there is still a verybroad cross section of systems in the field. That puts technical staff,Vessa says, in the position of “trying to get to a commondenominator that will translate on one side or the other of what wehave set up on the mixing stage. It has to work both for systems thattend to be more warm and boomy and systems that tend to be thin andbright. Both of which you find in the home.”

Compounding the issue of speaker response is the fact that thespeakers are so much closer in the home than in a theater. “Whenyou bring something into your home and you hear it on near-fieldspeakers, you immediately get different sensations out of thesound,” Vessa says. He also points out that the screen itselfaffects the sound in a theatrical environment. So a crucial part ofsetting up the mix is “getting the speakers out from behind thescreen and up close. Appreciating what's really coming out of thespeakers, as opposed to what it's sounding like from a distance behinda screen — that's a lot of it right there.”

Even with near-field monitors arrayed up close, questions remainabout how best to calibrate the system for a home theater mix,including both high- and low-end response. In large part that's becausetheatrical playback systems are set up to the “X-curve,” aresponse curve defined in ISO 2969 (SMPTE 202M). “On the top end,the X-curve starts at 2kHz and is attenuated 3dB per octave going upthe spectrum, ” says Steckling. “So when you're tuning fora big theatrical mix, your display should show 3dB per octave goingdown in a nice line from 2kHz. There's an X-curve for the bottom sideas well: 3dB per octave going down from 63Hz.”

While the frequency response of home theater speakers is all overthe map, it's rarely as attenuated on the high end as the X-curve. So amix made to sound good on an X-curve playback system — intheaters and dubbing stages — is unlikely to sound good on a hometheater setup. “It can be really bright in somebody'shome,” Vessa says. “And we're not talking about that nice,silky high end that's way out there. We're talking about something inthe harsh register, 4kHz to 8kHz. Dialog can be in there, sibilancescan be in there, and effects, especially metallic-type effects, cantrash your ears in there.”

Because of the closeness and brightness, playback of an X-curve mixthrough a home theater system also tends to reveal imperfections thatwere not noticeable on an X-curve system. “You hear all kinds ofthings that no one ever heard from the speakers in the theaters,”Vessa says. “Distortions, for example, and punch-ins.”Unexpected low-end activity can also be a problem, because hometheaters use a “bass management” scheme that is not takeninto account in theatrical mixing (see “Bass Management”sidebar, page 62).

“There's a tendency for people in the theatrical environmentto push a lot of level,” says Vessa. “They got used to theway mag forgave that to some extent with kind of a soft compression. Intoday's world of digital recording, there is a finite ceiling pastwhich the results are unpredictable and vary on different playbacksystems. In a theatrical environment, these ‘overs’ are notnoticed or they are forgiven. But we have found that when you put thosevery same levels onto DVD and hear it near-field, it's notforgiven.”

Given the unwelcome consequences, it's clear that simple transfer ofthe theatrical print master is not the ideal approach to DVD sound.From fairly early in the format's life efforts were underway in variousquarters to find a better way. One approach has been used by RobertMargouleff and Brant Biles, whose aptly-named Mi Casa studios bringsthe audio-for-DVD mastering process into an actual home environment(see “Mi Casa Studios,” mixonline.com, December2002). Others — including Don Eklund, chief engineer at Sony'sDigital Authoring Center in the early days of DVD — have viewedDVD optimization as a process that takes place on the mixing stage asan extension of a film's theatrical mix. In this case, the challenge isto define a stage-based mixing environment that consistently yieldsgood results for home theater.

The Men In Black DVD was the first opportunity for Eklund toput his ideas into practice. “A special mix was created to see ifthey could resolve some of the issues they were noticing with thetheatrical print master,” Vessa says. “In doing so, theywere able to repair some of the problems and also optimize thesoundtrack for the DVD release.”

The approach, says Vessa, “started off really simple: Let'sset up some smaller speakers, let's put it to digital tape instead ofmag. When I started in ‘98, Don handed it over to me and said,‘Run with it.’” The result is a setup specificationthat has grown into an 18-page document that guides audio masterpreparation for every Sony Pictures Entertainment film destined for DVD(see “The Sony Setup” sidebar, page 63). “You keeplistening, honing in on something that allows you to say, ‘If Iuse this environment, it'll translate,’” says Vessa.“That's really what you're looking for.”

A smaller room that emulates a home environment may be optimal if ithas enough inputs and the mixer is willing to mix there, but Vessa'sspecification is oriented toward working on a theatrical stage with anear-field monitor setup. Monitor volume is reduced to 80SPL to moreclosely simulate a realistic home listening level, and compatibility ischecked on a standard television. The suggested overall mix strategyinvolves, according to Vessa, “a moderate reduction in thedynamic range compared to the theatrical presentation. Soft sectionsare raised, especially music and dialogue, but often background effectsand soft Foley as well. Very loud sections may need to be pulledback.” The priority is that “the home listener should nothave to continually adjust their volume up and down to hear the detailclearly.”

If the idea is to simulate a home listening experience, one mightwonder about the need for pages of detailed requirements for thecomponents and calibration of the monitors. Why not run down to thenearest electronics superstore and pick up a $300 surround system?“Because then you really don't trust it,” Vessa says.“You need a good enough system,” Steckling agrees.“[It's important] to be able to tell the difference betweenwhat's on the track and what's happening in the monitors,” hesays. “So if something's distorting, you know it's on thetrack.”

Another factor is that the use of a consumer-level monitoring systemwould be disorienting to the mixers. “The mixer needs to feelgood about listening to something that's not totally different fromwhat they're used to,” Vessa says. “It's been hard enougheven to get some mixers to just sit down to Genelecs or M&Ks.They've just come off of months with a movie at very loud volumes, andeverything's very large, and then, regardless of what the system is,when you go near field a lot of them are like, ‘My God, I don'tknow quite what to do with this.’ So you've got to give them goodenough quality that they can start to fiddle, and go, ‘Gee, Ireally do hear that little move I'm making.’ Then they can startreally getting inside the speakers and trusting the results.”

This last point underscores the importance both Vessa and Stecklingplace on engaging a film's theatrical mixers in the DVD optimizationprocess. “The director and sound designer are often off tosomething else, and they want to feel that the DVD is in goodhands,” Steckling says. “ So they are happier that a mixerfrom the film — someone they trust and that knows the film— is dealing with the DVD.”

Vessa agrees that if you stay with the same mixer, “you'regoing to get a translated product — the experience that theoriginal mixer has with the movie is key to maintaining the integrityof the film's vision. I know that the mixers from the film that I'veworked with have certainly appreciated the opportunity to have a listenin this environment to see if they want to do anything to it and to dothe tweaks themselves. Sometimes, however, the mixing team is on toanother project directly and is not available. But as long as you'vegot the participation of someone else from the production that knowsthe original intent and sound choices of the film, it doesn'tnecessarily have to be the same mixer.” The main point, as Vessawrites in his specification, is that “the end results willtranslate well to the home environment, where the film will be enjoyedlong after the theatrical run.”

Bass Management Low-Down

In multi-channel theatrical systems, the sound reproduced by thesubwoofer comes exclusively from the Low Frequency Effects (LFE) track,meaning that the sounds have all been explicitly assigned to the subduring the mix. “The frequency response on a typical theatersystem drops off like a rock at about 40Hz — sometimes as high as45Hz, 46Hz, 47Hz, says Skywalker Sound's Jerry Steckling. “Sowhen a film is mixed, there is easily information below 40 Hz thatcan't be heard on the mixing stage, and you don't hear it in thetheaters. Nobody even knows what's down there below 40Hz in the screenchannels.”

Home theater systems use “bass management,” in whichlow-frequency sounds (typically below 80Hz) from the front and surroundchannels are “crossed-over” and routed to the sub, wherethey are mixed with the LFE channel. The idea is to prevent thesesignals from overloading small, limited-range satellite speakers andinstead direct them to a transducer capable of low-frequencyreproduction. But Sony's Brian Vessa says the results can beunexpected. “If you've got front channel information on the printmaster in that 20Hz to 40Hz band, in a bass management system that willget redirected to the subwoofer. You've never heard it before, but nowit's coming out in the sub, which already has everything that wassteered directly to the LFE channel. You may be very surprised at someof the buildup that you get down there — all of a sudden thesub's really talking.”

One fix is to keep energy below 40Hz off the theatrical print masterexcept in the LFE channel. “That way, if the theatrical mix endsup on the DVD, you're not going to get real surprised with all thisstuff under 40Hz suddenly popping out,” says Steckling. Adifferent approach is based on the fact that not everybody has asubwoofer or has bass management engaged. “Initially I'll do myprinting without listening to bass management,” Vessa says.“Then I do an entire playback with the bass management on, and Imake notes. If anything is popping out that shouldn't be, we'll go backin and catch it on a fix pass. So that way I hear it both ways, becauseit needs to work in both environments.”
— P.D.

The Sony Setup

Sony Picture Entertainment's document “SPE Specifications forthe Creation of Home Theater Printmasters” covers the creationfrom theatrical stems of both 5.1 and Lt/Rt (for Pro Logic)printmasters that “optimize a film soundtrack for homepresentation.” The specifications define requirements and setupfor a home theater remix on a full mixing stage.

In terms of near-field speaker placement, SPE calls for the threefront speakers to be set in an arc 7ft. to 8ft. in front of the mixposition, with left and right each 3.5ft. to 4ft. out from center. Thespeakers are placed on stands adjusted to 6in. to 8in. above theconsole meter bridge and angled down toward the mix position. Left andright surrounds are placed 4ft. to 6ft. behind and to the sides of themix position at an angle of 110 degrees. The front and surroundspeakers are each calibrated for 80 SPL, C-weighted using a spectralanalyzer. As for the sub, it generally goes in front, but may bepositioned as needed to achieve the desired response. Subwoofercalibration is +10db higher in its passband relative to the averagespectral level of the nearfields.

Regarding the speakers employed, the specification recommendsGenelec 1031A self-powered speakers and a Genelec 1094A or similarself-powered subwoofer. The 1031As are to be used with the -2db rolloffswitch engaged on the tweeter only, with all other switches in flatposition. “The -2dB switch puts a gentle shelf on the top,”says Sony's Brian Vessa. “It doesn't let the response just gowide open out to the sky, because you would never have that athome.”

It is “a perfectly reasonable approach,” says Vessa, touse quality near-fields other than Genelecs. “I did FinalFantasy through M&Ks,” he says, “and it came outjust fine.” He suggests, though, that M&Ks be used withoutany roll-off because “M&Ks out of the box aren't as bright asthe Genelecs.” As to why he specified Genelecs in SPE'srequirements, he says it's because of “the detail they give. Ifthere's something that can be heard, if there's a bad punch-in, an oddsibilance, a weird panning — anything like that — you'rereally going to hear it. Because everything's very detailed, and veryimage oriented, in those speakers.”
— P.D.

DVD Remix at Zaentz

We definitely believe that it is essential to remix films for theDVD release,” says Jim Austin, chief engineer at Saul Zaentz FilmCenter in Berkeley, Calif., which has garnered three Academy Awards forBest Sound. “It's not a major remix, but when the changes aredone properly, the result really allows the film to play properly inthe home environment.”

Austin describes four main reasons that DVD releases can typicallybenefit from additional optimization. “Because the DVD willalmost always be played back at a lower volume,” he says,“you want to reduce the overall dynamic range of the mix. You canalso change the mix level and/or equalization of certain elementsbecause the DVD is played through speakers with a high-frequencyresponse that extends flat an octave or more beyond that of a dubbingstage. Because home theater systems use bass management, you can changethe low-frequency content as needed in both the main channels and theLFE. And due to the closer placement and less dispersed sound of thesurround speakers, you can change the mix to maintain the desiredspatial effect.”

To create an appropriate environment for home theater sound on amixing stage, the Zaentz facility's setup procedures are based largelyon guidelines developed by Brian Vessa of Sony Pictures Entertainment(see “The Sony Setup” sidebar, page XX). “We use fiveGenelec 1032s set 10ft. away from the mix position and a home theatreREL Stendor III subwoofer with system management by StudioTechnologies,” Austin says. “The monitor level is set at82dBc. We also check the two-track stereo mix on a television withdecent built-in speakers, set to 78dBc.”

Despite Austin's conviction that tweaking the mix for DVD is a must,making the case to the Center's largely independent clientele cansometimes be a tough sell. “The studios actually releasing theDVDs mostly seem to understand the need for a DVD pass,” Austinsays. “But quite often that is a different company at a differenttime, not the clients who mix the original. Most independent producersare still reluctant to pay for a separate DVD mix.”
— P.D.