iTunes and 24-Bit Music Files?

02/22/2011

A report from CNN suggests that Apple is moving iTunes toward 24-bit music files. What this means is that, instead of using 16-bit CD-quality files (AIFF or WAV files) to convert to the AAC format that iTunes sells, they would use masters which are recorded at 24 bits. But this makes little sense, if Apple were to simply continue to sell files in compressed AAC format.

24-bit files offer only one major improvement over 16-bit files: an increase in dynamic range, or the difference between the softest and loudest parts of music. This difference would, however, be lost if the files were compressed. So the only way that Apple could offer improved quality in the music files they sell is if there were to provide them in Apple Lossless format.

Apple Lossless format does support 24-bit audio, but given the quality of digital-analog converters (DACs) in most computers – Macs included – listeners would not notice much of a difference. While many audiophiles swear by lossless formats, the only possibility to hear a difference between them and lossy formats at decent bit rates is with very expensive audio equipment. (And even then, the placebo effect certainly comes into play.) Users who have an external DAC that supports 24-bit files might see a small improvement, at least as far as the dynamic range is concerned, but other than that, there aren’t many advantages to selling this format for use on computers and iPods. (Some may find this forum post and thread interesting for a heated discussion of the differences between 16- and 24-bit audio.)

The differences between 16-bit and 24-bit files can be somewhat complex, and 24-bit files can take up as much as three times as much disk space as 16-bit files. While Apple may want to get into the “studio master” market – a number of classical labels sell files in 24-bit / 96 khz format – it is likely that only a very small percentage of users would buy such files. The audiophile market is a niche market to start with, and files in this type of format won’t attract many listeners.

This said, if Apple were to offer files in Apple Lossless format as on option, this could attract a group of listeners who refuse to buy compressed music. With file sizes (at 16 bits) of a bit less than twice the size of Apple’s current 256 kbps files, they don’t represent a huge leap in bandwidth and storage space requirements. When burned to CD – if anyone still does that – they reproduce the exact data that was on the original CD. And, since they require more space, it’s possible that users would buy larger capacity iPods.

The trend in music downloads, at least for classical music, is toward lossless files (generally in FLAC format). Apple is a laggard in this respect, despite the fact that they offer their own lossless format. It’s obvious that Apple will make this step one day, but going to 24-bit would be only for a limited number of tracks, and most likely only for those tracks that would attract audiophiles. Lady Gaga in 24 bits still sounds the same.

One more thing: the Apple Lossless format supports 5.1 audio tracks. I’d be far more interested in surround sound than 24-bit audio. While I could only play it on my living room stereo, assuming that it could be correctly streamed through my Apple TV, this would be something that might be more popular. Though not many albums are available in 5.1 mixes yet.