SRS TruVolume: Why another volume leveler?
Given that TV makers can already choose from at least two volume-leveling technologies— Audyssey Dynamic Volume and Dolby Volume—the announcement that SRS has launched a competing technology might be greeted with the same excitement as a new brand of HDMI cable. According to SRS chief technology officer Alan Kraemer, though, SRS’s TruVolume technology has a big advantage over its competitors … and his pitch is not the usual “we’re better” spiel.
Technologies such as TruVolume seek to solve the decades-old problem of loud commercials blaring out at double the volume of the TV show you’re watching. In the past, manufacturers have tried to quash such outbursts using primitive automatic level circuits, but in Kraemer’s words, “Those either did nothing or really messed up the sound.”
Like its competitors, TruVolume employs the science of psychoacoustics to keep the volume at a cozy level. “For example, you don’t perceive a 20-decibel shift in loudness at low frequencies as much as you perceive it in the midband,” Kraemer explained. SRS used this knowledge to shape TruVolume. To prevent the annoying “breathing” or “pumping” of background noise that an automatic level control can cause, TruVolume continuously analyzes 20 frequency bands, and applies different levels of gain control to each band. Its effects are more extreme in the midrange, and subtler in the bass and treble.
The benefits for TV watchers are obvious, but Kraemer says other types of material can profit from having TruSurround watch over their gain. “If you’re using a streaming service like Pandora or YouTube, where sound is coming from a lot of different sources, the volume can really jump all over the place. TruVolume keeps it all at a comfortable level,” he said.
Kraemer pointed out a few minor differences between TruVolume and its competitors (mainly that “Dolby is less aggressive in controlling volume jumps”), but his frequent use of the pronoun “we” to refer to Audyssey, Dolby, and SRS as a group showed how softly he’s beating that drum. He did point out one advantage, though, that might make TruVolume far more ubiquitous: It’s less expensive to add to a product.
“TruVolume consumes about half the MIPS of Dolby Volume,” he stated. By MIPS, he was referring to the “millions of instructions per second” that a digital signal processing chip inside a TV is required to execute. The more MIPS a technology uses, the more powerful (and expensive) a DSP chip it requires. “Our whole thing is to chew up fewer MIPS and accomplish the same thing or more,” he noted. “A relatively inexpensive DSP chip can implement this. Cirrus Logic has also created a drop-in TruVolume module with analog input and output that manufacturers can add to products that don’t have DSP chips.”
Or as the makers of those obnoxiously loud commercials might put it: You're not gonna pay a lot for this muffler.
TruVolume debuted in the Vizio VSB210WS soundbar, and it’s also made its way into several new Samsung and Vizio TVs. (According to SRS, the technology behind TruVolume was originally called Volume IQ and was announced in January 2008.) Kraemer said SRS had just signed a major manufacturer of set-top boxes as a TruVolume licensee, but wouldn’t reveal the company’s name.
Although it’s possible that TruVolume will work itself into more standalone audio products, Kraemer said the real potential beyond the TV market lies in iPhones and BlackBerrys. “We’ve created a variant of TruVolume called MaxV that’s optimized for smartphones,” he explained. “If you’re trying to watch TV or a video on a smartphone, and you’re in a noisy place, you can’t hear the speaker. We control the dynamic range and also do frequency contouring for the speaker, so you get as much volume out of the phone as possible. It can also make your ringtones a lot louder.”
Given SRS’s success in getting its technologies included in mass-market products, it seems TruVolume stands a good chance of making its way into your next TV set. “SRS technologies are already in about 40 percent of flat-panel TVs, so we expect a lot of them will add TruVolume,” Kraemer concluded.--Brent Butterworth