Blogs
Originally featured on BroadcastEngineering.com
Mar 19

Written by:
3/19/2012 4:33 AM  RssIcon

While passage of the CALM Act has consumers less susceptible to sudden spikes in the audio levels of the TV shows and commercials they watch, and politicians feeling good about themselves for passing “feel good” legislation, content creators and audiophiles are more than a bit concerned. They fear that stations will implement the cheapest solutions to solve the problem and in the process compress the levels and make the content far from what was originally intended. This, in turn, means a less than ideal listening environment, which is exactly what digital television audio sought to resolve.

Rich Cabot is founder and chief technology officer of Qualis Audio and a self-proclaimed audiophile.

Rich Cabot is founder and chief technology officer of Qualis Audio, a Lake Oswego, Oregon-based manufacturer of audio loudness monitoring technology as part of its Sentinel line of surround sound audio monitors. He’s also a self-described audiophile with a PhD degree in Surround Sound Psychoacoustics (he also co-founded the company Audio Precision, which he sold in 2001). For him, the issue hits home (theater).

“It’s unfortunate that [using a compressor] is the strategy that a lot of stations are taking, because the whole idea of broadcasting digital audio instead of NTSC was to get higher quality and here we sit with stations destroying the quality with compression.”

Most of the audio loudness processing devices on the market are based on software applications, so changes in the standard could be fixed fairly easily and without a wholesale equipment change. Yet, broadcasters are still weary. Network facilities are more prepared for the mandate, which officially goes into affect in December, than smaller stations.

“I’m seeing many local stations buying a compressor and feeling they are in compliance,” said Cabot. “It’s unfortunate, because that’s clearly not a good thing for the overall audio quality of a program or commercial. Producers and audio mixers spend hours and sometimes days getting the audio levels just right, only to have a station reduce the dynamic range to make it fit within their understanding of the government’s requirements. It’s a step back in audio quality, and some, like myself, might call it criminal.”

Cabot said that while the ATSC and subsequently the FCC have put forth a recommended practice for how stations can implement loudness protections, there are virtual loopholes in the commission’s Rules & Order that allow stations to comply while grossly mistreating the original content. One example, is that when you measure loudness levels in surround sound content, and then downmix it to stereo and measure the levels again, you will often get different results. Live sports is processed very differently than spoken dialogue. The issue becomes, when you normalize or standardize on a set of levels for one type of program, it does not bode well for another. This could get stations in trouble with viewers and ultimately, the CALM Act.

Another loophole states that if you use a compressor, you fall into what is known as “safe harbor,” and are in compliance with the law. The problem here is that there are no standards for how a compressor should work. There’s nothing that defines how much dynamic range a compressor takes away from the original content. So, using a compressor could mean some programs will be okay while others will not.

Qualis Audio’s Sentinel includes a feature that enables users to measure both 5.1 and stereo signals separately and then compare them.

In addition to verifying downmix compatibility and alarming when it detects problems, Qualis Audio’s Sentinel includes a feature that enables users to measure both 5.1 and stereo signals separately and then compare them. The unit only monitors and measures audio signals, it does not allow you to adjust levels. With algorithms that mimic human hearing, Cabot calls it “an electronic listener” for professional television audio mixers more attuned to video production. It didn't start out as a loudness monitor.

“There is no standard for what constitutes a compliant compressor,” Cabot said. “There is a standard for measuring loudness. If you take all content down to a -24 (+/-2) db dynamic range, it’s going to sound really bad. There’s just a big grey area in the existing standard that encourages people to simply throw a compressor on their output transmission stream and be done with it. It’s minimum effort and you get minimum results.”

In defense of the ATSC, it's a/85 standard “Techniques for Establishing and Maintaining Audio Loudness for Digital Television, which the government used to create the rules for the CALM Act—the group does not recommend using compressors and does not even explain how to implement them. The committee working on the original document (made up of representatives of all of the major TV networks as well as PBS and program providers), were careful to maintain a program’s integrity. Many agree that the CALM Act law was written with vague language that enables people to take advantage of its technical loopholes.

“From the conversations we’re having with stations, many broadcasters appear to be acting a bit tenuously about what technology to implement and how to implement it, because they don't want to install something that becomes obsolete in a year or so,” Cabot said, adding that while business has improved, but it’s not going gangbusters (as might be expected). “I don't think people are confident that the last word on audio loudness has been spoken, Broadcasters have been burned before by the FCC and they don't want it to happen again.”

Tags:
Categories:
Location: Blogs Parent Separator BE Blogs

Your name:
Gravatar Preview
Your email:
(Optional) Email used only to show Gravatar.
Your website:
Title:
Comment:
Add Comment   Cancel 




Monday 6:39AM
What Price Reliability?
Digitally delivered TV has seen a pile o’ fail lately.


 
Featured Articles
Discover TV Technology