Prosound News - April 2008 - (Page 47)

audioforvideo&broadcast Loudness Management: by Steve Harvey ith a little more than 10 months remaining before the exclusive adoption of the ATSC standard, questions regarding the management of audio loudness are likely to elicit different responses from different people within the broadcast industry. The ATSC standard, using Dolby Labs’ average dialog measurement algorithm, requires dialnorm metadata to accompany digital television audio to consumers’ decoders, but its precise implementation varies between networks and between over-the-air and cable broadcasters, resulting in noticeable level differences from channel to channel as well as across program boundaries. The 5th Annual Surround Broadcast Conference is co-developed for the first time this year by Pro Sound News and the NAB, and will focus on the issues associated with loudness and loudness management. Jeff Riedmiller, broadcast product manager for Dolby Laboratories, the event’s main sponsor, has spent the last 10 years helping educate Dolby product users in the cable industry to ensure that the AC3 stream is properly decoded to feed downstream applications. “It’s taking advantage of dynamic range control and dialnorm. It’s all there for free in the system,” he points out. “It’s a different way of thinking, but it’s really not rocket science. Taking specialreport [47] Leveling the Playing Field W the first and simplest step will yield so much.” Throughout the cable industry, operators have been using the Dolby LM100 loudness meter to help them estimate the loudness and set dialnorm on their simulcast encoders, he continues. “More and more cable systems now are taking their analog tier down and duplicating it on digital. In doing so they have all these encoders on the head end. These encoders make AC3, and when you make AC3 you should pay attention to one or two things, and one of them is dialnorm.” At the conference, Riedmiller will discuss the benefits of Dolby’s new DP600 file-based program optimizer with early adopter Ivan Larsen of Time Warner, whose Midwest operations center schedules a quarter-million ad breaks a day across 2,400 insertion channels. With a significant portion of that ad content no longer manually ingested but delivered electronically, a file-based system has become a necessity. “If anyone could attest to setting dialnorm appropriately it would be him,” says Riedmiller. Robert Orban, founder and chief engineer of the Orban processor company, who kicks off the daylong conference with a technology presentation of the new Optimod 8585 digital surround audio processor, points out that it is also up to content producers to manage loudness responsibly. “I have to think that there is some sort of disconnect happening between some of the content providers’ mixers and what people want to hear,” he says. “I think the worst problem that I’m hearing—and I’m not the only one, so I don’t think that it’s that my ears are getting older—is that a lot of dialog is no longer intelligible. It used to be the first commandment of film sound mixing.” Orban adds, “I also believe that a lot of production sound is being used with singleended noise reduction that has the side effect of killing intelligibility by swallowing consonants.” Tim Carroll, founder and president of Linear Acoustic, will be exploring automatic loudness management schemes using existing ATSC audio sidechain metadata at the conference. He reports that the networks are addressing content production inconsistencies by putting practices into place that implement dialnorm. “The way NBC is going, and PBS and ABC and FOX, is that they are putting out a fixed dialnorm value and making their content average around that value. It’s saying, here’s your target area. If you want to manually compress it, if you want to sit down and mix this and use an LM100 or a DP600, go ahead. But we’re going to reject content if the average level doesn’t end up around -24 or -25 dBFS.” Robert Seidel, VP advanced technology and engineering at CBS, will present the network’s (continued on page 48) Relative Loudness: L oudness management is one of the most critical issues facing television broadcast audio engineers as the industry makes the transition to fully digital ATSC transmission. Researchers have toiled over many decades to solve the puzzle of how best to objectively represent perceived loudness, and the current crop of metering and monitoring tools for 5.1 and stereo integrate algorithms reflecting the current best science, including the findings recently codified in the ITU Recommendations BS.1770 and BS.1771. DK-Technologies is premiering its MSD100C loudness meter at this year’s NAB Show (booth N1533; www.dk-technologies.com). The standalone MSD100C—the software is also incorporated into the latest iterations of DK’s flagship MSD range of meters—incorporates ITU-R BS.1770 and BS.1771, and displays the loudness of individual audio channels as well as the sum of the left and right signals. The unit provides accurate loudness RTW’s DigitalMonitor 10500 Objectively Measuring the Subjective matching of audio from a number of different sources via a selection of working modes: Fast mode for real-time viewing of loudness, Integrated mode for measuring the loudness of a section or a complete recording and Gated mode for viewing loudness of material with long pauses, such as golf games. Information is displayed as a numeric readout on a Loudness Units (LU) scale (broadcaster-specific custom scales are available). It also features an audio vector oscilloscope, phase-correlation meter displays, a full VGA color display and an external VGA output. Dolby Laboratories’ LM100 Broadcast Loudness Meter (NAB booth N1814; www.dolby.com) measures the perceived loudness of dialog using a proprietary algorithm to provide a Dialogue Intelligence reading that objectively measures what viewers subjectively experience. Complementing other Dolby products (continued on page 50) prosoundnews.com April 2008 http://www.dk-technologies.com http://www.dk-technologies.com http://www.dolby.com http://prosoundnews.com

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Prosound News - April 2008 Sound Business Contents Sound Retail Mojo’s Working at NY Noise Studio Showcase: Jungle Room Studios Software Tech Tracks Sessions Nomad Takes Root TCB at NYC’s JSM SoundScreen White Space Turning Gray Audio for Video and Broadcast Field Reports:Sony PCM-D50 Linear PCM Recorder; Holophone H4 SuperMINI Surround Microphone Sound Innovations: Earthworks Audio PianoMic System Frozen Liquid Live Sound Showcase: Jill Scott Centerstage Soundcheck Sound People View From the Top Product Spotlight Advertiser Index Company Index Classifieds Music, Etc.

Prosound News - April 2008

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