Issue link: http://digital.copcomm.com/i/24970
Audio Innovations Linear Acoustic’s Tim Carroll and the AERO.qc: “Loudness is subjective, so in order to simulate the perception of loudness, the measurement has to be integrated over a period of time.” better imaging since you are producing sound from the drivers themselves and not having the cabinet resonate along with it.” The MicroMain 27 and MicroMain 35’s unique design of dual subwoofers mounted on the side of the speaker cabinet has addi- tional benefits that can be heard in the mix- ing studio.“The sweet spot does benefit de- pending on the room, of course,” explains Barefoot. “Studios traditionally will have problems with low-end, so if you are using a 2.1 set-up, where you have a separate sub- woofer on the floor, you are exaggerating any low-end problems a room may have. That’s because a single source subwoofer on the floor by a wall will exasperate any low- end issues. But when you lift the low-fre- quency drivers [the subwoofers] up off the floor and into the speaker cabinet, then the room is not subject to as many problems.” Barefoot is planning for more innovations in the future.“Because of my background, I never really had a benchmark based on an- other speaker company that I wanted to surpass. I am looking to push the boundaries of this technology in my speakers.There are many things that can be done, this is just the first step.” LINEAR ACOUSTICS Tim Carroll, founder/ president of Linear Acoustic (www.linearacoustic.com) in Lan- caster, PA, has a simple goal of ensuring the exact same quality done in audio post pro- duction is the same as what gets aired over broadcast TV. Carroll is recognized by The National Academy of Television Arts and Sci- ences (NATAS) for his contribution in the creation of Dolby E while working at Dolby Labs. He remains actively involved in the cre- ation of DTV standards and practices. After leaving Dolby in 2001, Carroll founded Linear Acoustic to offer innovative solutions for managing stereo,multi-channel surround sound audio, and loudness issues for digital broadcasting. His philosophy cen- ters on using the right metering and loudness manager early on during the time of content 36 Post • February 2011 creation at the audio facility. By doing so, one is more likely to deliver audio requiring little additional processing when broadcast.“Dur- ing the days of NTSC, things could sound great in an audio studio, but the thinking was that no one could tell what it was going to sound like on the air,” says Carroll.“Now with DTV, post still has the same quest of deliver- ing high quality, but now there is a much bet- ter chance that content will make it to the consumer with the original production values intact. I have a respect for what gets done in post and I want to see that same quality pre- served when it’s broadcast.” The metering and loudness solutions of- fered by Linear Acoustic, such as the AERO.qc, the LQ-1000, and the AERO.file put the audio post facility on the same page as the broadcast network. This gives the audio post facility a preview, in a sense, of what will happen to the audio during a broadcast.“If people deliver a mix and don’t pay attention to loudness, then they are opening the door for other people down the line to get their fingers into the content,” says Carroll. “By contrast, if someone has produced a 5.1 mix that matches a common loudness target, which in the US is -24, then they have much less of a chance of their content being monkeyed with.” When problems do arise, Carroll offers some advice:“Correcting problems can be done in several ways. Number one, if you are making content, then use a meter.That way if we can help you get it right from the beginning, you don’t have to worry about the rest of the broadcast chain. Number two, if that is not possible and you are a broadcaster, there are file-based tools that will help you ingest the material correctly. Number three, there is the catch-all device at the end of the chain that is doing things like watermarking, Dolby Digital encoding, or managing the metadata. But, don’t leave everything to that last step. Get things cor- rect before it is too late and someone else has to take control.” Carroll adds, “Unlike 16 years ago when www.postmagazine.com there were no such tools available, any kind of adjustment meant that you had to go back to a post room. Now, simple fixes can be done without necessarily having to get into billable studio time.” The Linear Acoustic product line goes be- yond metering digital audio in the world of DTV. “There is metering but we do many other things, explains Carroll.“The AERO.qc is actually a processing device at heart and it contains metering. One thing we know from working with our customers is that if a meter tells you something is wrong, then something probably needs to be done about it.That’s what the AERO.qc does. It offers the tools to modify during the ingest process. It can also be used live.We used 24 of them during the Vancouver Olympics.The metering was one part of it, but it was also doing stereo to 5.1 upmixing.There are a whole host of things that are available, like peak limiting built in, and a way to calibrate the listening environment that you are mixing in. For example, if you have to ingest local content to a server in re- altime, then the AERO.qc will let you meter, monitor and correct at the same time.There is overall level adjustment, but that is not to be confused with something that a mixing console does, like adjust the levels of the sur- rounds only.That starts to get into modifying the artistic intent of the content and that’s not the purpose of the box. Once you get into that area, you probably need to go back to the mix stage.” To understand the importance of me- tering for DTV, one must understand the LKFS measurement. Carroll explains, “LKFS is the nomenclature for the measurement of Loudness, K-weighted, with respect to Full Scale. It was standardized in ITU-R BS.1770, which is about three years old now, which is still new to some people. But it’s not really that new. “Ultimately LKFS is a simple power-based RMS measurement,” continues Carroll.“The important thing is that the measurement be integrated over time unlike a PPM or a peak meter where you are getting an instanta-