AAC vs AIFF vs Lossless - Audio Quality vs File Size

As already mentioned these days music tracks purchased from the iTunes Store are all 256kbps AAC format.

I perfectly understand the need to use something like AAC for your iPhone due to the more limited storage of an iPhone compared to a computer. Apple also realise this - or do so now. 😉

Oldtimers will recall that Apple sold a version of iPod called the 'iPod Shuffle' this was little more than a USB memory stick with a headphone port. Like USB memory sticks it had a very limited amount of storage, as a result Apple chose to automatically convert any high quality music tracks to AAC format when being synced to an iPod Shuffle, this allowed you to keep your computer iTunes library with full CD quality tracks e.g. in Apple Lossless format but automatically sync them in a lower quality but much smaller file size when syncing to an iPod Shuffle without needing to make duplicate copies.

Time moved on and Apple introduced the iPod Touch and the iPhone both of which like the iPod Shuffle use flash memory for storage and have less capacity than a computer and also less capacity than the 'iPod Classic'. However at this time Apple did not provide the ability for iTunes to auto convert when syncing like they did for the iPod Shuffle. I actually contacted Apple about this and asked them to add the ability to do this for syncing to iPhones etc. for the same reason and I must have been successfully because they did subsequently add this ability when syncing to iPhones etc.

You can therefore do the following and still have your computers iTunes library with potentially just Apple Lossless tracks and use AAC on your iPhone. See http://www.ilounge.com/index.php/articles/comments/syncing-lossless-tracks-to-ip od-as-aac-files

As an aside here is my perspective on choice of music format.

Apple Lossles aka ALAC, FLAC, AIFF and WAV are all lossless formats and if the track is from an original audio CD all of these formats will keep the same exact quality as the original audio CD. AIFF and WAV will require exactly the same amount of storage space as the track does on the CD, whereas ALAC and FLAC being compressed but still lossless will take less space. Roughly speaking ALAC and FLAC use the same amount of space and compared to the AIFF, WAV or CD track this will be about half the space.

Let me repeat ALAC, FLAC, AIFF and WAV should all sound the same since they are all lossless copies of the audio CD track.

So in terms of audio quality vs file size ALAC and FLAC are roughly equal and both are superior to AIFF and WAV.

The next issues to consider are usability and compatibility.

Some programs can support things like embedding album artwork and meta tags in AIFF files e.g. iTunes, some programs can do this for WAV files e.g. Windows Media Player. However iTunes cannot do this for WAV files and WMP cannot do this for AIFF files. Both iTunes and WMP can however do this for ALAC files.

Note: iTunes does not support FLAC files so obviously it cannot do this for FLAC files.

Therefore ALAC is the better choice if you want to use the same lossless quality track in both iTunes and WMP.

It is possible to fully use ALAC files in WMP and even Microsoft Media Center in Windows XP onwards although for XP, Vista, and 7 you need to install both an additional codec and a meta tag handler. For Windows 8 and 8.1 WMP has a built-in ALAC codec but still needs a meta tag handler, for Windows 10 WMP has full built-in support for ALAC even down to embedded album artwork meaning nothing extra needs to be installed. As it happens I came up with the original solution to allow WMP in Windows XP to play ALAC files and was therefore the very first person to do this in the entire world.

ALAC these days is a free open-source format - hence it now being officially supported by Microsoft, and it is also supported by many other programs and devices, e.g. Foobar2000, WinAmp, dbPowerAmp, WMP, Media Center, VLC, Plex, KodiTV, Sonos, Logitech Squeezebox, etc. etc. and of course all Apple's devices such as iPod, iPhones, iPads and Apple TV.

Therefore unless you are using a device e.g. Android which does not support Apple Lossless you should I suggest use Apple Lossless rather than FLAC, AIFF or WAV.

AIFF is lossless, i.e., CD quality. If you import from CD as AIFF then the results will - subject to limitations of your audio hardware - be the same as listening to the original CD. In terms of audio quality AIFF and WAV are identical; for use in iTunes the latter is best avoided, though, since the WAV format has no ability to embed metadata or artwork. All iTunes Store purchases are AAC/256kpbs - using lossy compression so that there is less information than in the equivalent CD or lossless version. There is no benefit of converting from AAC to AIFF - the "missing bits" cannot be restored. Although there are a few specialist retailers that support purchase/download of lossless audio (typically using FLAC encoding) the range of material available tends to be much more limited than mainstream sources such as the iTunes Store, Amazon or Google Play.

In terms of audio quality, you will notice a difference between lossless (such as AIFF) and loss (AAC or MP3) based on:

• Quality of your playback system - a difference that is obvious on a high-end hi-fi system may be negligible on desktop speakers or standard headphones.
• The nature of the music/recordings you're listening to - contemporary popular music (most genres) tends to be heavily compressed during mastering - sacrificing dynamic range for loudness. Indeed, many such recordings are probably engineered/mastered to sound as good as possible on iPods/phones/PC speakers - you'd probably hear very little difference between lossy and lossless versions of a Katy Perry or Taylor Swift song, whereas it would be immediately obvious with a good classical or jazz recording.
• The degree of compression used in the lossy encoding - AAC and MP3 at 256kbps or higher is often fine for casual listening - at lower bitrates degradation of audio quality becomes more noticeable.
• Your own hearing and preferences!

Given these factors there's no possible "universal recommendation" - though if you primarily use iTunes as a source for playback via a good quality audio chain (D>A conversion / amp / speakers or headphones) then lossless (AIFF) may be preferable. If your listening is more likely to be via commodity headphones or desktop speakers, or using an iPod/iPhone, then the quality benefits of lossless are marginal at best.

I misspoke slightly before - AIFF is uncompressed lossless* - essentially a container for WAV data - whereas Apple Lossless (also known as ALAC) is a compressed lossless encoding. They are identical in terms of audio quality, but the file sizes for ALAC will, in general, be smaller than those for AIFF. The degree of compression varies with source material, but ALAC files will generally be around 50-60% of the equivalent WAV file, ITunes Match does not get "max audio quality" - it replaces lower quality lossy files with the 256kpbs AAC files that are available from the iTunes Store (but no better than that).

* there are actually many variants on AIFF, some of which do include compression, but the one used for CD imports in iTunes uses uncompressed PCM data.

I have been experimenting with FLAC (lossless but not recognised by iTunes) converted to Apple Lossless and CD ripped to Apple Lossless. On an iPhone 5s and iPod 4G with good earphones there is an audible difference to standard files. The lossless files are smoother and richer with greater dynamic range, but without good 'phones I do not think it would be noticed. Whether it is enough to compensate the storage required is another question. I tend not to buy through iTunes as other stores sell higher bitrate files, and will often go for a FLAC version if available and convert it to Apple lossless. I also find that CD's are sometimes cheaper than purchasing online, with the option to rip to lossless encoding. There is in my view sometimes a penalty for the convenience of iTunes.

All downloaded music is a trade off between file size and quality - to keep device users happy. I have noticed slightly better quality ripping a CD to 256 than the same track downloaded at nominally the same quality. The bitrate does not indicate the effects of compression - use a good ripper and see the range of file options available for a given format.... Throw in mastering variations and bitrate and format are indicative at best.

Thanks for the informative post.