This article is interesting, but it seems written by computer people and not audio people. There
seems to be some misunderstandings about how D-A works in the real world, and even how lossy formats
are applied to full-resolution audio.
My own use and listening tests tell me that toothpaste-mastered audio sounds crappy in any
resolution but it CAN (but doesn't always) sound even worse out of an iPod because the iPod DAC and
post-DAC analog circuitry seems to add distortion, as is the case with many sound cards. My
conclusion is that the circuitry is not spec'd out to handle constant digital-zero levels because no
rational person would expect it. To get loud enough for headphones on the battery power provided,
there's probably not enough current or voltage to blast out toothpasted stuff all day long. It seems
to my ears that the lossy elements of both MP3 and AAC make the distortion more noticeable and
"fuzzy" when played back through an iPod or a consumer-grade computer soundcard, more so at lower
(more lossy) resolutions.
I think the big thing Apple is pushing, but hiding it behind technical jargon, is for producers and
mastering engineers to keep more dynamic range in the music, master at a lower average level (ie
more room for peak dynamics) and try to "space out" the frequency spectrum a bit more. All of these
things will sound better in ANY resolution but may be more dramatic and noticeable via decent
headphones, and higher-resolution AAC and MP3 (high enough not to have digital pollution and
artifacts in the high end and leave in some "air and space" around things -- 320kbps seems to be OK
in MP3 and 256 may be OK in AAC in some cases but probably not for sonically complex music). So I
think Apple has muddied the waters a bit, but what they are calling for is better "best practices"
regarding dynamics and average level. They are pushing high-resolution masters because they're
probably hoping that more care will be taken throughout the process if people think they're working
in a "better sounding" format -- plus the ample documented reasons why DSP can work better at higher
resolution during production.
What I continue not to understand in all this is why doesn't Apple just release material in their
own lossless format? That would solve all the problems and quirks of lossy format conversions.
-- Tom Fine
----- Original Message -----
From: "Arthur Gaer" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, April 30, 2012 1:50 PM
Subject: [ARSCLIST] Does "Mastered for iTunes" matter to music?
An interesting, if not highly technical, piece on the effects of "Mastered for iTunes" on Ars
Technica:
"After our original report on the Mastered for iTunes program, some readers were skeptical that
anything could be done to make a compressed AAC file sound comparable to uncompressed, 16-bit
44.1kHz CD standard audio. Others believed users should have access to the original 24-bit 96kHz
files created in the studio for the best sound. Finally, some readers suggested that few people can
actually tell the difference between iTunes Plus tracks and CD audio, so why bother making any
effort to improve iTunes quality?...
"Shepard applauded Apple's technical guidelines, which encourage mastering engineers to use less
dynamic range compression, to refrain from pushing audio levels to the absolute limit, and to submit
24/96 files for direct conversion to 16/44.1 compressed iTunes Plus tracks. However, he doubted that
submitting such high quality files would result in much difference in final sound quality. Shepard's
conclusions led CE Pro to claim that Mastered for iTunes is nothing more than "marketing hype."
"So, we set out to delve deeper into the technical aspects of Mastered for iTunes. We also attempted
to do some of our own testing to see if there was any difference—good or bad—to be had from
following the example of Masterdisk.
"We enlisted Chicago Mastering Service engineers Jason Ward and Bob Weston to help us out, both of
whom were somewhat skeptical that any knob tweaking could result in a better iTunes experience. We
came away from the process learning that it absolutely is possible to improve the quality of
compressed iTunes Plus tracks with a little bit of work, that Apple's improved compression process
does result in a better sound, and that 24/96 files aren't a good format for consumers."
http://arstechnica.com/apple/news/2012/04/does-mastered-for-itunes-matter-to-music-ars-puts-it-to-the-test.ars
Over 140 comments made in the last 16 hours since the article was first posted--ranging from
know-plenty to know-nothings (but think they know-it-all).
Arthur Gaer
[log in to unmask]
Senior Systems Manager
Harvard University
Department of Mathematics
Science Center
1 Oxford Street
Cambridge, MA 02138
617-495-1610
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