Tom – I’m reprinting an email I got from one of our awesome listeners – John. While we have a lot of different kinds of listeners, I’m always impressed at just how smart they are. On top of that, they care about audio quality to do these sorts of things. Great work John and thanks for sharing!

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A few podcasts ago, when discussing Audio Diffmaker, Tom suggested we use that application to see what we’re getting from iTunes Match. Since I’ve already done quite a bit with audio difference files, I don’t expect to learn much there, but I did look at and listen to an original file, a matched file, and a Mastered for iTunes file.

The track is “It Could Happen to You” by Diana Krall from the album From This Moment On. I picked this track randomly from the few I could have used for this test.

Here’s an Audacity shot of the original in Apple Lossless:

Here’s the matched file from iTunes:

Seeing that the matched file seemed to be a more clipped version of the original (Tom – the red bars indicate clipping), I broke down and spent 99 cents to purchase the Mastered for iTunes version:

This is clearly a different master, and iTunes Match does not currently give you the Mastered for iTunes version when matching.

Next, I ran these tracks through TT Dynamic Range Meter, which is an application that quantifies dynamic range for audio tracks. As a point of reference, a dynamic range of 12 is considered very good, while a dynamic range of 8 is considered the minimum for acceptable quality.

TT Dynamic Range Meter for Mac (zip file)
TT Dynamic Range Meter for Windows (zip file)

Original: Dynamic Range Value of 10
———————————————–
Statistics for:    01 It Could Happen To You.m4a
Number of Samples:    9191616
———————————————–

Left        Right

Peak value:    -0.02 dB        -0.02 dB
Avg RMS:    -12.14 dB        -11.91 dB
DR channel:    10.07 dB        9.69 dB
———————————————–

Official DR value:    DR10
===============================================

iTunes Match: Dynamic Range Value of 10
———————————————–
Statistics for:    01 It Could Happen To You.m4a
Number of Samples:    9101652
———————————————–

Left        Right

Peak value:    over        over
Avg RMS:    -12.08 dB        -11.86 dB
DR channel:    10.06 dB        9.68 dB
———————————————–

Official DR value:    DR10
===============================================

Mastered for iTunes: Dynamic Range Value of 12
———————————————–
Statistics for:    01 It Could Happen to You.m4a
Number of Samples:    9162735
———————————————–

Left        Right

Peak value:    -0.06 dB        over
Avg RMS:    -13.50 dB        -14.20 dB
DR channel:    11.56 dB        11.84 dB
———————————————–

Official DR value:    DR12
===============================================

So the Mastered for iTunes version has greater dynamic range than the original CD. It’s also rolled off a bit in the upper frequencies with a very slight increase in mid-bass, which is visible in Audacity’s Plot Spectrum analysis.

They clearly did something with this Mastered for iTunes version that was an attempt to improve the sound. To me, they all sound very good, but it’s good to know that this doesn’t appear to be a rebranding/ripoff kind of thing on the part of Apple.

One more point about dynamic range compression. Tom has come to the realization that dynamic range compression is just a part of today’s music. While I understand that point of view, dynamic range does compromise sound of what could be quality recordings. While I don’t care if Kanye’s latest has a Dynamic Range of 2 or 3, I’d prefer Adele’s 21 to have a better dynamic range than the 7 that it does.

Dynamic range compression also compromises remasters of older recordings.

Dire Straits “Walk of Life” from the original CD, Dynamic Range of 13

Dire Straits “Walk of Life” iTunes Matched version, Dynamic Range of 6 (with a bit of clipping, I’d say)

This is basically the loudness war ruining of a very good recording.

I find all of this interesting. Disappointed to find that iTunes Match is not matching with the Mastered for iTunes version. I hear compression and clipping much easier than I hear the difference between a good AAC conversion and the original CD, so for my purposes, I would choose a 256 AAC Mastered for iTunes version over a lesser quality master on CD.  Hopefully, the Mastered for iTunes parameters, which include a recommendation to keep dynamic range and avoid clipping, will help guide toward improved mastering for all media.

John

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