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-   -   iTunes audio format choice? (http://hintsforums.macworld.com/showthread.php?t=168433)

benwiggy 01-03-2013 09:22 AM

iTunes audio format choice?
 
I'm finally getting round to putting ALL my CDs onto my iTunes Library, now that I've got multi-terabyte storage, and what with Phil Schiller telling me that optical drives are "for those stuck in the past".

I've started off using Apple Lossless Encoding, for quality, but I was somewhat shocked at the filesizes. I'm getting c. 40-50Mb for a standard pop song, and 300 - 500Mb for a whole disk. That's 40%-60%, which is in line with what Wikipedia tells me. But it's bigger than I was expecting, and considerably more than .aac, which typically does c. 50Mb for a whole album.

OK, file size is less of an issue that it used to be, but I'm looking at c. 100Gb on ALC, versus c. 10Gb as AAC (if I've done my maths right). And space is still limited on my iDevices, of course.
I'm wondering if I should convert my ALC files to AAC, or just carry on using AAC for the remainder. Basically: is the quality/size ratio worth the extra?

I'm not an audiophile who can hear the gaps between the samples :p but I'm just wondering if anyone has any thoughts. I'm also concerned about future compatibility.

NaOH 01-03-2013 12:49 PM

I've done my whole (large) collection in 192 kbps AACs. In addition to reasonable file sizes, the AAC format seems to work well with iDevices in terms of the effect of battery life. I'm absolutely not an audiophile, but there was another thread in which Trevor noted that I could drop down to 128 kbps and I wouldn't notice any difference while saving a little more space.

Personally, I prefer to have all my files in my preferred format. It means that I won't have to track down larger-size encodings if space ever becomes an issue, nor will I have additional considerations when it comes to other conversions I might do. I simply know that all my files are of one type and one encoding rate. Understandably, you may not see that as worthwhile.

When it comes to future compatibility, I don't see much reason to be concerned with AAC. It's not an Apple format, so I am confident that if iTunes or iDevices ever drops support for it, then there is likely to be something out there which I can use for conversion (XLD, Max, etc.).

onceagain 01-03-2013 01:09 PM

I originally did AAC, but that will not play in my car's 6 disc mp3 player, so I converted them all to MP3s. It's 500GB - I imagine it would be a lot more with AAC.

trevor 01-03-2013 01:11 PM

Quote:

Originally Posted by NaOH (Post 715734)
I'm absolutely not an audiophile, but there was another thread in which Trevor noted that I could drop down to 128 kbps and I wouldn't notice any difference while saving a little more space.

Hmmmm, I don't *think* that that was me. I typically encode at 256 kbps stereo MP3. Unless I was talking about strictly spoken word audio? That sounds fine to me at 128 kbps in either AAC or MP3.

To my ears, music at 128 kbps AAC sounds alright in treble frequencies, but sounds weak (lacking in that nice thump) in the bass. 128 kbps MP3 on the other hand, sounds acceptable in the bass but there's a weird warble in the treble frequencies that bugs me a lot. If I was forced to use 128 kbps, I'd use AAC every time.

192 kbps AAC and MP3 are getting a bit better, but I'm not really happy until I get to 256 kbps. Even at that bitrate, I think MP3 is a little better-sounding than AAC in the low frequencies, and it's problems in the high frequencies are really really hard for me to hear, and it's compatible with more devices, so I use MP3 at 256 kbps.

Quote:

Originally Posted by NaOH
When it comes to future compatibility, I don't see much reason to be concerned with AAC. It's not an Apple format, so I am confident that if iTunes or iDevices ever drops support for it, then there is likely to be something out there which I can use for conversion (XLD, Max, etc.).

Agreed.

Trevor

NaOH 01-03-2013 01:19 PM

Quote:

Originally Posted by trevor (Post 715737)
Hmmmm, I don't *think* that that was me. I typically encode at 256 kbps stereo MP3. Unless I was talking about strictly spoken word audio? That sounds fine to me at 128 kbps in either AAC or MP3.

A quick search suggests my memory was off and you're correct about not having made such a statement. I should have checked beforehand. Sorry for attributing misinformation to you, and thanks for dropping in and clarifying your position.

benwiggy 01-04-2013 04:19 AM

Quote:

Originally Posted by NaOH (Post 715734)
When it comes to future compatibility, I don't see much reason to be concerned with AAC.

I was more concerned with the compatibility of Apple Lossless!

Anyway, I've re-encoded all my songs to aac. Half my music is already in that format, and I can't really tell the difference, even for classical.*
It means I can get much more on my iPhone/iPod.

The new MacMini processed each one in under 2 seconds -- 79 x playback speed! iTunes process took 125% of a core. Total CPU barely hit 20%. Nice.:p

NaOH 01-04-2013 01:41 PM

Quote:

Originally Posted by benwiggy (Post 715753)
I was more concerned with the compatibility of Apple Lossless!

I realize this doesn't matter now since you moved everything to AAC, but I figure the Apple Lossless is more likely to go away or will be more difficult to future-proof since it's Apple that controls the format. That's not to say such a change is likely—what do I know?—but it wouldn't be the first time Apple unexpectedly dropped support for a format, a means of connectivity, etc.

fracai 01-07-2013 08:19 AM

I don't think many (sane) people consider lossless audio to be a requirement for listening, it's usually kept for archiving. Sure, MP3 and AAC are good formats today, but what about in a few years when there are codecs that provide better quality at smaller sizes? If you've archived losslessly, it's just a matter of the computer time to recompress everything. If you haven't stored lossless copies, you'll have to reimport. Or re-buy or hope that your vendor provides downloads for your purchases in the new formats (to their credit, Apple has done this when they upgraded the iTunes library).

Also, Apple Lossless isn't really under Apple's control. For one, there have been 3rd party, reverse-engineered libraries for years, and Apple also released the source code not too long ago. Even if they drop support, it's fairly trivial to batch convert Apple Lossless to FLAC or some other lossless format.

Finally, there are listening test apps that will help you determine what quality makes sense for your ears. My findings have been that for AAC 128 is fine and 192 is more than enough, but I don't have the results of my listening tests handy and you should conduct your own anyway. (gah, have to remind myself that not every forum has the same rules as Hydrogen Audio)


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