What 'Mastered For iTunes' Really Means

You could say that the story of the recording industry over the last decade and a half — the era since the MP3 rattled its game plan — has been a struggle to find a balance between the consumer's demand for widespread access to music, the artist's desire for high-quality product and the industry's need for compensation.

Last month, Apple made a move that subtly shifts this balance when they began selling albums in a new section of the iTunes store called "Mastered for iTunes."

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Apple introduced the news quietly, and it was received mostly as a behind-the-scenes tech development — I noticed a long piece about the development in Ars Technica before I saw the banner ad in the iTunes store — but it says a lot, I think, about the company's understanding of what listeners want from their digital audio files.

Over and over, technology has changed both the way we record sound and the way we listen to it. New formats are greeted with fanfare, but often, in the first years after supposed advancements, recordings suffer as technicians adapt old techniques. Early CDs were just digital versions of recordings mastered for vinyl, and sounded terrible. Recording engineers adapted, which triggered a craze for remastering (and repackaging, and re-purchasing) those albums for the new format. But MP3s have always been seen by the industry — and many consumers — as a transitional product of compromised quality.

Users accepted that compromise because of the huge gains in convenience — no more carrying around booklets of CDs or waiting weeks for your local record store to restock a physical format. Among many, the hope, for the duration of the MP3 era, has been that quality would steadily improve in tandem with bandwidth and storage capabilities, so that eventually the quality of downloadable digital files would equal or surpass that of files burned onto little plastic discs. For a decade, we were on a road to a musical utopia: great-sounding audio files that we could send from one place to another with ease.

The basic goal of the "Mastered for iTunes" store essentially cuts that ideal off at the knees, or at least points to the fact that we may have already been off that road for some time.

I'll get to that in a minute. First, a few necessary words about mastering:

The music you listen to, no matter what the format, sounds worse than it does in the studio where it was recorded. That's not just because musicians and recording engineers have better equipment than you do, but because the recordings themselves contain more information. Today, most studio tracks are recorded at 24 bits. The process of mastering a recording is taking the raw, mixed song and copying it to another format, with adjustments in the amount of information that can be transferred to the new medium and attendant tweaks to ensure it sounds as good as possible given the new format's limitations. The music on standard commercial CDs is encoded at 16 bits.

Even so, the slightly compressed digital files on CDs are called "lossless" files because you can still take the quality down another step and have something most people enjoy listening to. When you rip a song from a CD into iTunes as a "lossy" file like an MP3 (or AAC, Apple's preferred format), you're using a compression codec, a program designed to eliminate the parts of the sound in a song that you don't notice or can't hear.

The triumph of MP3 and AAC formats is that they remove an enormous amount of the information contained within a recording without making it sound like they're removing an enormous amount of information. When we listen to a digital file (especially on a better sound system), we might be able to tell that something is missing, but that something might be so peripheral to what we think of as enjoyable about music that we're willing to trade the slight downgrade in quality for the huge step up in convenience.

Today, convenience is winning the war. Since reaching its peak in 2001, sales of CDs have declined by nearly 69 percent, according to statistics from Nielsen SoundScan, while digital album sales continue to rise. In its guide to mastering for iTunes, Apple says, "Digital distribution is no longer an afterthought. It is today's dominant medium for consuming music and as such needs to be treated with utmost care and attention."

If the implication there, that we haven't been treating our portable, compressed audio files with proper care, makes you think that Apple is finally moving toward a hi-def format, you'd be wrong. Instead, the company is asking bands and their labels to submit songs to the store that are encoded as AAC files directly from the original, 24-bit studio recordings.

In Apple's calculation, mastering a song or album "for iTunes" means that it'll sound better while remaining just as portable as the encoded files we're accustomed to packing by the thousands onto our phones and mobile devices. For Bob Ludwig, a mastering engineer who remastered Coldplay's latest album, Mylo Xyloto, for the new "Mastered for iTunes" store, this makes sense. "From a technical viewpoint, there are cases where the lossy 24-bit AAC file would be superior to the lossless CD," Ludwig wrote in an email. "I did an early demonstration for some engineer friends of mine and the difference between the 'Mastered for iTunes' file I created and the one that was ripped from a 16-bit CD was easily heard on the little speakers on my MacBook Pro."

I listened to the two versions of Coldplay's single, "Every Teardrop Is A Waterfall," to test the difference. (I can't post audio samples of the two versions of the track here because the encoding process a file goes through in any audio editor obscures those subtle differences, but if you have a CD version of any of the albums in the "Mastered for iTunes" section of the store, you can compare easily by ripping the tracks at "iTunes Plus" quality.) Played over decent headphones, I could hear subtle differences, especially where the mix was denser and more complicated. Ludwig's "Mastered for iTunes" version sounds slightly less crowded, with clearer distinctions between similar tones in acoustic guitar and piano and sharper, less distorted drums.

That's partly because Apple is providing mastering engineers with software that helps tweak individual songs that will be encoded as AACs, rather than relying on a standardized encoding process — as intelligently designed as it might be — to handle the compression correctly. It's a crucial step, because tracks mastered for AAC aren't technically of higher quality; they're just made to sound as good as possible within the restrictions of the format.

There's an implication there that bugs some people who believe iTunes, which is the single largest music retailer in the world, should do more to push the market toward higher-quality files, where those restrictions don't exist. John Vanderslice, a musician who owns Tiny Telephone, a recording studio in San Francisco where Death Cab For Cutie, Spoon, The Mountain Goats, Kronos Quartet and tUnE-yArDs have all recorded, thinks that asking the industry to make a commitment to highly compressed digital files is misguided.

Vanderslice's studio doesn't do mastering, but as a musician, producer and studio owner, he hears many albums before and after the mastering process. "The idea of mastering is that you have the definitive high resolution product and you wilfully ignore every other variable downstream," he says, "whether it's compression codecs or speakers or whether someone's listening to it on earbuds."

The idea of mastering for a lesser format, Vanderslice says, is "completely insane. My first reaction was it would be like if you were a writer and you were told that you would have to re-edit your book for the dimwitted or the dyslexic."

Here's another technological analogy: pan and scan, the process by which films were cropped from their original widescreen aspect ratios in order to be played on televisions in the 1980s. Annoying for nearly everyone involved, to be sure, but accepted as a reality of the marketplace back when none of us had widescreen TVs hanging on our walls. A skilled editor might have made the decisions about what part of the image was shown on the smaller screen, but the original work was still compromised.

So why would Apple embrace a inherently inferior format (and ask musicians to shell out thousands of dollars to tailor their songs for it)? Because what we're talking about here isn't actually about downloading songs. It's about streaming them.

To me, the only way "Mastered for iTunes" makes sense is as part of a calculation for a future that doesn't look like the one we planned on. If the MP3 opened the door to let convenience into the format conversation, streaming offers another world: every song you've ever heard or thought of available instantly as long as you've got a network connection. We've got cloud-based services coming out our ears: Apple's iCloud, Amazon's Cloud Drive, Google Music, Spotify and Rdio, to name just a few. And here, the size of a file still matters. Our connections may be fast enough to download high-quality, lossless audio files (and HD videos, for that matter), but streaming audio can tax cellular and broadband networks as well as users' data plans.

Streaming also changes our relationship with music itself — in moving toward a model that values nearly unlimited access, we're also approaching a reality in which the idea of owning a recording is a luxury. This is good for Apple, because high-quality audio costs more to store and to transmit to listeners, but also because it gets to dictate the terms under which the idea of "quality" will be determined. For people like Vanderslice, who want studio-quality recordings in their home libraries, this might not actually be a bad thing. If the vast majority of the audience accepts streaming services as good enough, the few who want to buy songs — in physical or digital formats — might be able to demand higher quality for their money.

UPDATE Wednesday, March 7, 2012 @ 1:50 p.m.

As some of you have pointed out in the comments, this post contains incorrect information about the files that mastering engineers are submitting to Apple to be sold in the "Mastered for iTunes" section of the store. I wrote:

"The implication there, that we haven't been treating our portable, compressed audio files with proper care, makes you think that Apple is finally moving toward a hi-def format, you'd be wrong. Instead, the company is asking bands and their labels to submit songs to the store that are encoded as AAC files directly from the original, 24-bit studio recordings."

The last part of this paragraph is incorrect, and the error changes the way I understand what Apple's doing. Apple didn't respond to requests for comment (they're a little busy right now), but I spoke again with Bob Ludwig, the mastering engineer quoted in the story, who has submitted "Mastered for iTunes" tracks to Apple. He says the company is simply providing mastering engineers with tools that allow them to see how songs mastered at 24 bits will clip (that is, distort audibly) when they go through the standardized AAC encoding process. That's been difficult to do in the past. Seeing the places where all lossy encoders creates clipping in the music gives engineers a reference for how to adjust the master recordings to avoid that distortion. The uncompressed files are then submitted to iTunes, which creates lossless versions before encoding the songs as 256 kpbs AAC files for sale in the iTunes store. (Through the testing process, Apple has even been submitting its encoded AAC files to mastering engineers to make sure the process hasn't created any unforeseen errors.)

Why is this significant? Because the fact that Apple retains the lossless versions of the high-quality studio masters means that iTunes, at any time it decides to, can begin selling higher-quality encodes, or even lossless files. If this story is, at bottom, about how the demands of consumers shift the balance between convenience and quality, then this new development is Apple's effort to allow humans to correct flaws in a very useful but imperfect technology. It does not mean that the company is locking its users into an inferior format.

I didn't write this post to complain about Apple's continued sale of 256kpbs AAC files (though there are plenty of people who wish the company would offer higher-quality encodes or, even better, a lossless option). What drew me to this story was the fact that it gives us an opportunity to mark a moment where the largest music retailer in the world seems to be making two significant moves: to create tools to make a better end result with any lossy codec while suggesting that lossy formats will likely be a part of our lives for the foreseeable future. Because the way we listen to music is so tied to a rapidly shifting technology, moments like that happen regularly. It's not often, though, that we get to note them in real time.