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My iTunes music library consists of iTunes downloads (256 kbps), and songs copied from my CD's (~400 – 1100 kbps). I have a dumb playlist containing a subset of these, which I sync to my iPod Nano (it doesn't have room for my entire library(. Also on the nano are other dumb playlists, each containing specific songs that are subsets of my main dumb playlist, which are tailored to my various workouts.

Recently, however, I've started listening to audiobooks on my Nano, which means I need to free up more room, so I'd like to replace all the CD-quality songs on my nano with 320 kbps versions (and I'd likewise like to still be able to use my various workout playlists). I thus had iTunes create 320 kbps versions of all my CD-quality songs. What I'd like to do is create smart playlists containing only songs whose bitrate is 320 kbps, and whose title matches a song found in a specified dumb playlist. This doesn't seem to be possible, but if it is I'd love to find out how!

Yes, I could just leave things as they are and, from within the Nano control window available in iTunes, tell iTunes to convert everything on my Nano to 256 kbps. But, since I have the space for 320 kbps, why not keep the maximum resolution? Granted, I might have trouble telling the difference....

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For a portable device using headphones in a non-analytical environment, I'd just sync them at 128 kbps AAC.
You're really unlikely to notice.

You can do that in iTunes/[device]/summary in the last section, Options. It does that on the fly at sync [so takes a long time, first time] & keeps your iTunes at full rez, using copies to send to the portable device. You can set this separately for each device you sync, the low-bitrate dupes are kept in your iTunes Library once converted, but iTunes always plays the highest rate available.

It's effectively seamless

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As a more generalised comment, & speaking as a professional sound engineer, I don't think tracks ripped from CD are worth saving at anything higher than 320kbps AAC*. Much as they were vaunted as being the 'perfect solution' for audio... in the 80's... they really don't have all that much data in them to benefit from anything above 320.

*or FLAC, but as iTunes doesn't handle FLAC, that point is moot.

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  • Thanks for your post. As I mentioned in my question, I already know how to do what you describe. Question: I'm aware of the limitations of CD's. And it may be hard to tell a difference between a CD and a lossy conversion thereof to 320 kbps. But what did you mean when your wrote "they don't have all that much data ... to benefit from anything above 320", since my CD's average roughly 700–800 kbps? It sounds like you meant to refer to the practical sonic information content of the data, rather than its quantity.
    – theorist
    Mar 3, 2018 at 21:09
  • CD audio is 16-bit 44.1KHz. That limits how much 'fidelity' it can hold. Converting that to 24-bit 88.2 KHz would gain no more information, only fill the file with empty bits. Similarly for any lossy conversion, after so far you run out of practical gain & into 'the number is higher therefore it must be better' territory. Don't believe the hype.
    – Tetsujin
    Mar 4, 2018 at 8:26
  • The example you gave is for upsampling 16/44 PCM to 24/88 PCM. Of course, in that case, no new information is added, so there's no benefit. But that doesn't apply to my case, as I'm going in the opposite direction. Specifically, your example doesn't explain why, when starting with 16/44 (bit rate 1411 kbps), and converting to AAC, there's no benefit to a bit rate >320 bps. BTW, I also have a background in digital audio, having written a technical paper to support the introduction of a new D/A converter during the 90's. That means I'm familiar with PCM, but not the newer codecs, like AAC.
    – theorist
    Mar 4, 2018 at 17:33
  • Then it's off to Google to read some papers. I'm 'just' a sound engineer, not a theoretical mathematician.
    – Tetsujin
    Mar 4, 2018 at 17:46

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