What is High-Resolution Audio?

High Resolution Audio Means Greater Than CD Quality Music.
April 27, 2012

InstallationRecently CEPro interviewed Jack Shafton of GoldenEar Technology, who does a great job explaining digital audio formats. The shift away from CDs, the development of iTunes and downloadable music and the digital audio market’s place in the music world compared to CDs and vinyl has created a need to understand digital audio formats. Portable music has ushered in exciting and amazing changes in how and where we listen to music. People love having their music available to them at all times. Streaming services and downloads from the Internet have allowed us to discover new music in ways we never imagined.

Early portable music players relied on physical media sources like cassettes and CDs that limited their effectiveness. But as technologies improved, people were able to put lesser quality, low resolution audio files on solid-state and small hard drive-enabled devices and this fueled the market’s explosion.This paradigm changed the way people listened to music, particularly through the ability to easily pick and choose a song or build a playlist.

With storage becoming more affordable, it is now easier for consumers to catalog higher-resolution audio files and experience a better way to listen to music.

High Resolution Audio
Dick Shafton explains: "High-resolution audio is generally considered to be that which is recorded or natively transferred from analog at higher than CD level resolution. I think it is important to understand a bit of the technical aspects of high-resolution audio such as just how much data it represents and I think it’s instructive to start at the point of where we started: lossy, low-resolution audio.”

Here is how Shafton describes three common digital audio terms:

Lossy Audio: Looking at the lossless and lossy audio formats, lossless audio means what its name suggests - whatever the recording quality was, you have bit-for-bit data representation. Lossy audio formats use perceptual coding techniques to discard data in order to reduce digital file size and they allow users to store more music files in the same amount of space as a lossless file. The challenge for perceptual coders is to figure out what parts of the music are unimportant enough to throw away forever in order to reduce the file size but yet still sound like music.

CD Quality: As a baseline, let's use lossless CD quality audio (44,100 samples per second at 16 bit depth, two channels). For clarity, the sample rate figure defines maximum recordable frequency (it is half the sample rate) and bits defines the maximum dynamic range available (defines dynamic range: 16 bits equals a theoretical maximum of 96 dB).

To quantify this, CD quality audio is 1411 kbps, or kilobits per second (44,100 x 16 x 2). The total of 1411 kbps is also called the bitrate. The lossy format 128 kbps bitrate that was defined in the lossy audio definition gives up a lot of quality. The math for a lossy format with a 128kbps bitrate is simple and it equates to the music missing about 91 percent of its original data.

There are much higher bitrate lossy files available to consumers. MP3 can go up to 320 kbps, which sounds immensely better than 128 kbps, but it's still throwing away 77 percent of the original musical information.

High-Resolution Audio: Comparing high-resolution audio to CD is very similar to the lossless vs. lossy discussion, except lossy audio is CD resolution. Of course, it's not really lossy but recording at 16-bit/44kHz levels doesn't capture as much data as high-resolution does. High-resolution music is often available in three or four forms, with the most common being 24/96 and 24/192.

That means either 24-bit with 96,000 samples per second or 24-bit with 192,000 samples per second. 24/96 recordings can capture a little more than three times the data as CD resolution and 24/192 can capture nearly seven times the data as the CD format. While we may or may not be able to hear above 20,000 Hz (20kHz), there is a lot of musical energy at those levels of the hearing spectrum and high-resolution formats can capture all of that information.

Digital Music Playback Methods
Unlike the early days of true digital audio, there now are many ways to playback content. Starting with streaming audio from the web, consumers can listen to Internet music services such as Pandora, Rhapsody, Spotify and Last.fm. These web services vary in sound quality, but the web offers an ever growing choice of services and Internet radio stations that range in cost from free to services that are subscription only.

Shafton says a hardwired Ethernet connection would be the best method to connect to the Internet, but Wi-Fi is a perfectly viable solution, too.

Stepping up the quality ladder, the next level of performance is locally-stored music files that reside on a computer or networked attached storage (NAS) device. Shafton says the homeowner will need some type of software to play these digital files. He says iTunes is an acceptable solution, but unlike some of the other solutions on the market, newer versions of iTunes don’t support the playback of high-resolution audio files.

Shafton also says homeowners will need some type of remote control, which could be something as simple as an Apple iOS or Android app and a digital to analog converter (DAC) to facilitate connections to standard consumer audio equipment.

The Opportunities Digital Audio Offers
Because of the massive success streaming audio, iTunes and other technologies have enjoyed, Shafton asserts that electronics professionals are already widely using digital audio in the field. He says that currently what is affecting the market is the rapid development of technologies that promote global accessibility.

Shafton continues: “Digital audio is already the most common demonstration format,” he suggests. “What is changing is being able to listen to a music collection anywhere in the home and having that music being accessible from an app on a smart phone or web tablet.”

Indeed CE dealers are able to show clients the capabilities of today’s new audio technologies and how convenient it is to access music from anywhere. Shafton says: “Not only can they show their customers cool new ways and places to hear their music, they can also play it at CD or better resolutions and show them that convenience and performance go together.”

For example Control4 systems play digital music in MP3, M4A (Apple), and FLAC (Free Lossless Audio Codec) digital formats. The system will scan NAS drives, PC network drives, USB attached flash drives, or home controller local memory to identify music files in the above formats. The system will search the Internet for meta data on each song and add the song to the music library, similar to Windows Media Player or iTunes.

A free Media Edition of the Composer PC software allows homeowners to add/remove content from the music or video libraries and create playlists. These playlists can then be launched in "shuffle" and/or "repeat" mode based on an event occurence detected by the system. The event is normally a "button press", but it could be someone entering a bathroom (equipped with a motion sensor and stereo speakers) at bath time triggering the launch of a "soothing music" playlist!

The interview with Dick Shafton was published in CEPro by author Robert Archer on 4/23/2012.