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Has iTunes mastered audio?

Mastering engineer Crispin Murray speculates with Erica Basnicki about Apple’s potential plans to deliver 24-bit/96kHz audio.

In February 2012, Apple launched its Mastered for iTunes initiative, providing mastering engineers with a set of tools to help create the best-sounding tracks possible when converted to a 256 variable bit-rate Advanced Audio Coding (AAC) file – the new standard format offered on iTunes (also known as iTunes Plus).

Ever since, stories have circulated that Apple may offer “high-definition” 24-bit/96kHz audio sometime in the perhaps not-so-distant future. Apple’s own Mastered for iTunes technical document hints at this, perhaps, stating:

As technology advances and bandwidth, storage, battery life and processor power increase, keeping the highest quality masters available in our systems allows for full advantage of future improvements to your music. Also, though it may not be apparent because there may not always be a physical, tangible master created in LP or CD format, the iTunes catalog forms an important part of the world’s historical and cultural record. These masters matter – especially given the move into the Cloud on post-PC devices.

Apple’s rumoured plan to offer high-resolution digital files is welcome news for audiophiles, but renowned mastering engineer Crispin Murray (pictured) says the mastering world has “a couple of concerns”. By encouraging the music industry to upload 24/96 production masters now, mastering engineers are effectively “heading towards a release format that we’re not actually mastering directly for”, he says.

“Although there are various people that are working for Apple that we can talk to about this, there’s nobody actually at Apple that’s approachable that’s talking directly to mastering engineers at an open level. It’s being presented pretty much as a fait accompli.”

Currently, Apple’s Mastered for iTunes droplet, freely available on its website, allows anyone to preview and create a track in the iTunes Plus format. The resulting file is downsampled to 44.1kHz.

Should iTunes’ 400 million active users start downloading uncompressed 24/96 audio files from Apple’s servers, the jump in bandwidth could “either knock them [Apple] out or slow them down substantially. So there’s a distinct likelihood they may be contemplating a 96kHz lossy codec, at which point you’re now two steps away in terms of mastering. You’ve sent them a file that’s optimised to go through a 44.1kHz codec, but they’re going to deliver it again through a 96kHz codec that no one’s heard. That’s a little bit of a concern,” says Murray.

Apple may have found a compromise already, with the Guardian and other online publications reporting that Fraunhofer’s new HD-AAC codec is the company’s format of choice. Released around three years ago, HD-AAC offers ‘adaptive streaming;’ delivering a full high-resolution audio file or lossless compression of 24-bit music content from the same file, based on bandwidth and storage available on the user’s device.

Apple won’t comment on the rumours, but its potential high-resolution audio roll-out also poses another question; who actually owns the high-resolution files? Or rather, who gets the money from that version?

“If a high-resolution file is sold for a higher price, and I’ve upgraded something I’ve already bought, will any money come back to the artist, or the writer? Will all that money go to Apple? I don’t know. Will some of it go to the record label, in which case why wouldn’t it go down to the artist…” commented Murray.

“It’s a bit of an interesting one. Having said that, we all know that in the last 25-30 years record companies have had a massive wealth come in as they’ve resold the same stuff everybody already had. We’ve already bought it on vinyl, on cassette, and then we bought it again on CD. Everybody’s bought the same thing two or three times over.”

There is nothing quite like the unknown to invoke concern and speculation. What Murray does know about the Mastered for iTunes initiative is that the sound of digital files offered on iTunes is improving. Additionally, Apple’s iTunes Plus format has proven to be an audiophile’s unexpected ally in the ‘loudness wars’.

Murray explains: “Peak or clipped signals don’t code very well. If you have a clipped signal and try to do any processing on it, you end up with a very large spike, which of course is a click. This is one of the reasons why Apple is so hot on getting rid of clipping.”

And despite concerns about delivering for a format no one has heard (yet), Murray argues there is potentially a great psychological benefit to having Apple deliver high-resolution audio.

In the days of cassettes and Walkmans, “you used to have to think in the morning about what two or three cassettes to take with you, and you made a conscious decision about what you were going to listen to, whereas now you can be a bit less conscious about making that decision; you’ve got 6,000 tracks in your pocket. Maybe with higher resolution files we’ll be more conscious of what we listen to again,” says Murray.

Erica Basnicki