SMPTE Newswatch Masthead
  4 January 2013

NW1Hot Button Discussion

Next Generation Cinema Audio  

By Michael Goldman 


In the world of theatrical sound, there are two important issues that SMPTE Technology Committees and sound system manufacturers are expected to focus on in 2013, closely followed by content creators and exhibitors. The first issue revolves around the growing need to improve ways to standardize testing, measurement, and calibration of theatrical sound systems in order to arrive at consistent playback between theaters. The second major issue involves expanding and improving multichannel playback to provide the cinema listening audience with "immersive" sound, including audio playback technologies and techniques designed specifically to keep pace with new picture display breakthroughs, such as 3D and higher frame rate exhibition.


The December 2012 issue of the SMPTE Motion Imaging Journal was dedicated entirely to these and other matters related to cinema audio. Industry veteran Tom Scott, a SMPTE Engineering Director, pulled together a series of technical papers in the issue devoted to progress in analyzing, testing and monitoring theatrical audio systems, and improving on current standards. He points out that the measurement and standardization topic is "one of the larger issues going on right now" in the industry. That is the reason why the SMPTE ST-SG Theater B-chain study group was formed, working with other industry organizations to develop new measurement and calibration standards and procedures.


"In the 1970s, when stereo sound first became popular on 35mm film, the techniques for setting equalization effectively--tone controls--for loudspeakers in theaters were standardized by SMPTE," Scott explains. "That standardization was based on certain analog tools--the types of mics and analyzer equipment available then, which listened to a test signal in a theater, sent through the loudspeakers and through the perforated screens. In motion picture theaters, the main speakers are behind the perforated screen, and the sound comes through that plastic sheet with holes in it. The acoustics of a big reverberant space combined with squeezing sound through that screen take a toll on the sound experience. To assure distributors that their films would sound the same in different movie houses, standards and practices for calibration using the available techniques were put in place, and have been in use for 40 years."

"That standardization from the mid to late '70s stood the test of time for a while, but now, we have more sophisticated tools--computers to analyze sound in ways that were not available back then. That is why we set up the new technology committee in the last few months, to create standards and appropriate practices for measuring sound, using new digital tools in motion picture theaters."


"The Holy Grail we seek," Scott continues, "is to make theaters playing the same film sound similar in New York, Los Angeles, London, or anywhere. We believe this can be done if standards and practices consistent with modern sound systems and computerized tools and test signals can allow operators to calibrate similar equipment precisely in different theaters."


The original study group reporting to the SMPTE Standards Committee observed that incorrect calibration, excessive equalization, and poor room acoustics, among other factors, are all currently present in some movie theaters in the U.S. Thus was spawned the new 25CSS Technology committee, to examine the problems separately in the context of how to repair current installations, deal with new installations, and properly consider the needs and performance capabilities of evolving systems that feature additional playback channels. 

To move in that direction, researchers have performed computerized analysis of how sound from cinema loudspeakers travels through perforated screens. Scott says, "that effort is a hot one" because there is inevitable degradation to the signal as sound "squirts through the screen." Understanding the amount and nature of the degradation may be central to formulating new measurement practices. The December 2012 issue ofthe SMPTE Journal contains an extensive and detailed article documenting some of this work.


In another article in the December issue, Brian Vessa, now Chair of the new 25CSS Technology Committee, summarized the work and the recommendations of the original Study Group, which he also chaired--"this standards effort [was designed to] re-evaluate what needs to be measured, how to measure it, and what action should be taken, based on measurement results," he wrote in the article. Suggested future work will focus on developing new "measurement and calibration techniques that more closely correlate with how people hear, so that a measurement-only calibration procedure can deliver a highly consistent result."

Work is being launched to develop standards for theatrical sound system measurement and calibration, component performance, and theater acoustics. Five specific documents from the study group will be written to "create procedures and practices for making motion picture theaters increasingly interoperable in a standardized sort of way," said Scott. 


One prime consideration involves the fact that stereo and surround sound are no longer sufficient to achieve the visions of some motion picture directors and sound designers. Thus, "immersive sound" has risen to a prominent place in the discussion. Scott points to recent breakthroughs from Dolby® and other manufacturers aimed at "ways to deliver more channels that can envelope the audience with more detailed soundscapes and precisely controlled moving sound 'objects,' rather than simply squirting stationary sound through those perforated screens."


"Currently, the standard setup has three main speakers behind the screen for left, center, and right channels," he explains. "[The December issue of the SMPTE Journal] detailed the Dolby offering, Atmos™," which is the trade name for a highly sophisticated multichannel immersive system that arrived in early 2012 for the debut of Pixar's animated film, Brave, and has since been installed in dozens of theaters across the country. The notion is to permit, potentially, a large number of audio tracks to be digitally transmitted to theaters to be rendered and played back, according to that particular theater's sound system's capabilities.

"That means an Atmos Digital Cinema Package [DCP]--the files that make up what we used to call a soundtrack--can be played on older 5.1 or 7.1 channel sound systems, and yet take advantage of installations with channels exceeding those configurations, since each additional loudspeaker receives its own audio feed, and the theater 'knows' what it can do," Scott explains.


Scott notes that other immersive approaches from various manufacturers are on the way. He makes the larger point, however, that these developments are part of a wider industry discussion about how best to use more channels in theaters, and how to do so cost-effectively, since business models involving constant retrofitting of sound systems are hard to justify. He also emphasizes that costs are not relegated only to hardware retrofits, but ongoing maintenance to assure performance also costs money. Even as Atmos and other systems arrive, they carry corresponding testing and calibration requirements in tow.


"Atmos is a step beyond [what had been tried previously] because it requires hanging more speakers and equipment, much of it computerized, in theaters, and that means more calibration," he says. "The proper calibration of five to seven channels in a theater might take up a long morning. Calibrating 50 channels might take days. So new ways of calibrating these systems--ways to automate the process--are definitely areas that Dolby and other companies are researching and working hard on right now."

People are calling this immersive sound, or multichannel sound. Some of the new technology terms that Scott refers to include "object-based" and "soundfield synthesis." At the upcoming NAB Show's Technology Summit on Cinema (TSC): Advances in Image and Sound, produced in partnership with SMPTE, 6-7 April 2013 in Las Vegas, Scott says, "we [SMPTE] will have a session looking at those and other new ways to produce and control sound in motion-picture theaters. In the future, it is entirely possible that we will have dozens of channels coming from multiple directions, even overhead. We need to follow this closely--just because you can put more speakers into a theater doesn't mean that you should. After all, this is really about improving the moviegoing experience in theaters."

News Briefs

HFR Reactions    

In light of the debut of the new 3D tentpole feature, The Hobbit: An Unexpected Journey, from filmmaker Peter Jackson in the 48 frame/sec format, it is understandable that the industry is analyzing both the technical considerations of HFR exhibition, its creative and critical feedback, and potential aesthetic considerations, as well as what it all portends for upcoming similar efforts at higher frame rates. A recent issue of SMPTE Newswatch examined the trend, and now, writer Deborah Kaufman of Creative Cow Magazine, has written a survey piece talking to industry experts about what HFR's debut at the studio feature level means, and where it is going next. Her article points out that theatrical releases are hardly the only application for the technique. Special venue films, are in some respects pacing the trend by using HFR methods to create immersive experiences for audiences. One such project she references is attempting to combine 8k stereoscopic CG imagery with 4k 3D video to deliver what director/producer Barry Clark tells Kaufman will be "8k resolution at 60 frames/sec." Kaufman also spoke with Siegried Foessel, head of the Fraunhofer Department of Moving Picture Technologies, about his belief that 120 frames/sec might, in fact, be the best way to get "the more immersive or realistic look." Bryant Frazer at the Studio Daily website also spoke with Foessel in a recent interview about new developments at 120 frames/sec.

RPTV Era Ends    

The CEPro website recently reported on the demise of what was once a revolutionary display technology--rear projection television (RPTV). The report discussed the recent decision by Mitsubishi Electrical Visual Solutions America Inc. (MEVSA) to drop its rear-projection line of consumer televisions. Mitsubishi was the last company making the units, but said in a memo, according to the report, that the decision was merely the result of a restructuring of a business division. The move ends what was once a great success story for the technology, and Mitsubishi was its biggest player, having offered consumers one of the first 50-in. HD-capable rear-projection televisions in the mid-1990s. Over the years, the company had offered LCD flat panel and DLP RPTV's, 73-in. RPTV's, and 3D RPTV's, among other innovations in the category. Its only other major competitor in the RPTV world, Samsung, got out of the RPTV business in 2009.


Green Set-Top Boxes

The era of constantly running set-top cable boxes being a huge drain on consumer energy bills may be about to end. That's because the Consumer Electronics Association (CEA) and the National Cable and Telecommunications Association (NCTA) recently reached an agreement to put significant energy conservation requirements on set-top boxes, according to a report on the Broadcasting & Cable website. In their announcement, the two organizations stated they expect the agreement to result in as much as $1.5 billion in residential energy savings, since it will impact boxes made or supplied by most leading cable providers, such as Time Warner, Cox, Verizon, AT&T, Cablevision, DirectTV, Comcast, and others. The agreement started 1 January and requires at least 90% of all set-top boxes supplied by cable operators to meet EPA Energy Star 3.0 levels for the first time. The EPA estimates that would make such boxes approximately 45% more efficient than non-compliant boxes. To meet compliance the new boxes will be able to shift into different levels of sleep mode, depending on how long they are not being used.