In the age of highly compressed music files playing on iPods and even lower-quality Pandora streams playing on iPhones, some artists, music producers, and others in the music industry are apparently pushing for iTunes and other digital download services to adopt higher-fidelity 24-bit files. But while a small niche of audiophiles might appreciate the move, it seems unlikely that the necessary sea change in hardware and software will happen in order to support such a move, nor do we see consumers flocking to 24-bit files in order to make it economically viable.
According to music industry executives speaking to CNN, record labels are supposedly in discussions with Apple to begin offering 24-bit music files. Most of today's digital music is encoded using 16 bits per sample at a rate of 44.1kHz, including audio CDs, MP3s, and the AAC files used by iTunes. However, master recordings (or digital remasters from analog tape) tend to be done using 24 bits per sample at a rate of 96kHz, which offers a wider dynamic range with smoother waveforms. This wider dynamic range can capture subtle aural nuances that can be lost in the conversion to 16-bit format for audio CDs.
Add to that the fact that the large majority of music is further compressed using MP3 or AAC formats. These lossy formats use "psychoacoustic modeling" to compress the audio waveform by eliminating certain frequencies and harmonics that humans are least likely to notice are missing.
The difference between an uncompressed 24-bit/96kHz recording master and a 256kbps, 16-bit/44.1kHz iTunes Plus track is great indeed, and some in the music industry lament that listeners just aren't hearing what the artist intended. "What we're trying to do here is fix the degradation of music that the digital revolution has caused," Jimmy Iovine, head of Interscope-Geffen-A&M, said recently during an HP event to announce its new webOS-based mobile devices.
Dr. Dre, famed hip hop artist and producer—as well as Iovine's partner in Beats Audio—agrees. "Most of you aren't hearing [music] the way it's supposed to sound. And you should—hear it the way I do." HP uses Beats Audio hardware in some of its laptops, and will also incorporate the technology in its TouchPad tablet.
According to Iovine, Universal Music Group has been working with Apple to try and transition iTunes to 24-bit audio. "Apple has been great," Iovine said during the HP event. "We're working with them and other digital services—download services—to change to 24-bit. And some of their electronic devices are going to be changed as well. So we have a long road ahead of us."
A long road is right. While most Macs and PCS can natively handle 24-bit audio playback, none of the hundreds of millions of iPods sold can play back 24-bit files, nor can most PMPs, smartphones, or other mobile devices.
"Paul McCartney can master The Beatles albums all he wants, [but] when you play them through a Dell computer, it sounds like you're playing them through a portable television," Iovine said, suggesting such sound lacks depth. But remasters and master recordings use higher-quality sampling so that the conversion process to 16-bit format for CDs can be better controlled through mastering techniques.
To play back native 24-bit audio files, Apple would have to reengineer iPods and iPhones to use hardware decoders and 24-bit D/A converters that support 24-bit audio; computer and mobile device vendors would have to do the same. Without wide device support, 24-bit iTunes tracks make little sense.
The case could be made that 24-bit audio files would sound better, assuming consumers could (or would) get access to hardware capable of playing it, but there are other considerations at play. 24-bit audio files would also be larger than current digital music tracks, taking up more storage space and more time to download. The music industry is also looking at 24-bit files as something that could carry a premium price, so tracks could cost more as well.
There's some precedence for this in the digital music download market. When Apple introduced iTunes Plus in 2007, it increased the AAC compression rate from 128kbps to 256kbps. Along with the data rate increase—and elimination of DRM—came a price increase from 99¢ to $1.29 per song. Six months later, however, iTunes Plus tracks were dropped to 99¢.
(Yet more variable pricing came when Apple persuaded all record labels to standardize on the DRM-free format in 2009, but the price difference was not related to sound quality).
While some audiophiles can discern the difference between AAC tracks compressed at 128kbps versus 256kbps, or compressed tracks versus an uncompressed CD source, there's evidence to suggest most listeners can't, especially on low-end audio gear like iPods, cheap computer speakers, or compact home theater systems. Much like expensive Super Audio CDs (SACDs), the extra sound quality would only be of appreciable benefit to an extremely small niche of audiophiles with very expensive audio systems. While those customers would likely appreciate a higher quality download option, the music industry already provides them with higher-fidelity uncompressed formats, such as CDs, SACDs, and vinyl albums.
For the vast majority of listeners—many of which are satisfied with low-bit rate streams from the likes of Pandora—a transition to 24-bit audio would be superfluous.
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