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Topic: iTunes Plus setting

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Old 03-15-2009, 12:07 AM
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iTunes Plus setting

So another user at hydrogenaudio and I have been looking at iTunes' new iTunes Plus setting for encoding audio (ie ripping CDs). Before, iTunes just offered a "Higher Quality 256kbps" option where iTunes Plus is currently located. iTunes uses QuickTime for pretty much everything. So the 256kbps "CBR" setting produces results similar to QuickTime using the 256kbps ABR setting with "medium" quality. The iTunes 256kbps "VBR" setting produces results on par with QuickTime's 256kbps VBR constrained setting with "medium" quality. This new iTunes Plus setting (which iTunes says is 256kbps VBR) uses QuickTime's 256kbps VBR constrained setting but with "maximum" quality. I don't know if the difference between medium and maximum quality result in audible differences. After all, we are talking about extremely high bitrates here.

I encourage people to look at the new setting and determine what is right for them. Please don't discuss audio quality without providing blind ABX tests (switching back and forth in iTunes is not a blind ABX test!). Otherwise your claims would fall ill to the placebo affect and be nothing more than FUD.

I conducted a blind ABX test comparing a handful of lossless files to 256kbps "VBR" (using QuickTime's medium setting) and iTunes Plus files (all encoded in iTunes). I had trouble ABXing both files from the source lossless one. I basically failed the blind ABX tests so, to me, the iTunes Plus setting does not offer any audible improvement. File sizes are normally smaller by less than 1MB when using iTunes Plus over the standard VBR setting (at 256kbps) and overall average bitrates are normally increased by a few kbps (around 10kbps). It is interesting that Apple added this iTunes Plus settings. I found that it produces bitrates on par with modern iTunes Store purchases. However, when compared to older iTunes Store purchases, the bitrates are higher. In fact, the 256kbps CBR setting (now and back then) produces bitrates that are more on par with older iTunes Store purchases.

All-in-all it is interesting to look at but I don't see much coming from this "iTunes Plus" setting in iTunes. Hopefully it doesn't confuse people and I hope that others conduct actual blind ABX tests before making audio quality statements and advising others.



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Old 03-15-2009, 09:49 AM
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Quote:
Originally Posted by kornchild2002
All-in-all it is interesting to look at but I don't see much coming from this "iTunes Plus" setting in iTunes. Hopefully it doesn't confuse people and I hope that others conduct actual blind ABX tests before making audio quality statements and advising others.
I know that audio quality is one of your favorite subjects, but I believe you're overthinking this one. There is virtually nobody out there who is concerned and knowledgeable enough on this subject who was going for one of the handful of encoder presets in iTunes (it's a whole three in iTunes 8.1, one being for spoken word podcasts). This setting is there expressly for those people who don't want to worry about this stuff.

Sure, you and the guys at hydrogen audio can go all Plato and Socrates over exactly what is going on with the new preset versus the old one - wouldn't be audio geeks otherwise - but it comes down to a sort of navel gazing. The iTunes store has now embraced the notion that ~256kbps is higher quality than 128CBR kbps. This much is undoubtedly true, even my 38 y.o. ears can ABX some percentage (probably a bit more than 10%) of my music from lossless at 128CBR kbps, but there is no music I can ABX at any flavor of 256 kbps. I would guess that Apple settled on the general number of 256 because it is well beyond what all but some miniscule fraction of a percentage point of the population can ABX from lossless (my own complete failure begins around ~170 kbps, nowhere close to ~256). Bandwidth, storage capacity, the headphone market and, most importantly, consumer perception all have changed enough since 2003 that they decided to up the bitrate and they chose something that really ought to shut the overwhelming majority of complainers up (I'll keep on campaigning for lossless but, hey, that's me ). Having embarked on a similar mind game like they did in 2003 of convincing people the iTunes store's 128kbps represented "like CD quality", they needed a new default preset in iTunes for the new "better than like CD quality " the store now sells, and so we get the iTunes Plus preset. Whether they went with 256 at CBR, ABR or VBR or constrained versus unconstrained don't matter, it will be transparent to anybody who is choosing it and the VBR choice by default will save people a little disc space. It's not any more complicated than that.
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Old 03-15-2009, 12:59 PM
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Is there any news on this iTunes Plus employing an improved engine to reduce errors and other anomlies that I've read lowers iTunes-ripped file quality? Or is that in regards to their MP3 ripping engine?
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Old 03-15-2009, 02:40 PM
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Quote:
Originally Posted by jasn
Is there any news on this iTunes Plus employing an improved engine to reduce errors and other anomlies that I've read lowers iTunes-ripped file quality? Or is that in regards to their MP3 ripping engine?
No such thing as an mp3 ripping engine. You have the CD ripping component which reads raw audio data, aka .wave audio. That audio is then either stored as raw audio (.wave) or encoded to any lossless or lossy compression scheme. This is completely independent of the later compression encode and iTunes' ripping component is an average performer but contains no way to ensure fidelity. The iTunes AAC encoder is a good quality AAC encoder, nearly as good as the Nero AAC encoder. The mp3 encoder is simply a modified FhG encoder and therefore considered substandard compared to the LAME mp3 encoder.

To return to my point: if you care about fidelity, you will not be ripping with iTunes.
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