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I know it sounds subjective but its not meant to be. I am very new to ripping CD's using iTunes, and I'm confused over the different formats available. I have read Wikipedia regarding the AAC and Apple Lossless Formats (ALAC).

I read that Apple claims that ALAC is about 1/2 the size of other formats, but with my test, the ALAC files were huge! I cant rip them all and have room for all of my music on my phone at those sizes.

I do think they sounded better than AAC or MP3, however.What is the best format/bit rate in iTunes to rip CD's in, also considering the space and quality factors? Also, am I really losing any quality at all with AAC or MP3?

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This previous question addresses a similar subject, though not exactly the same. –  Ryan Thompson Apr 4 '11 at 3:52

9 Answers 9

up vote 12 down vote accepted

As you say, this is subjective. Technically you almost always loose quality if you rip to AAC/MP3 (it is called 'lossy' compression for a reason). The question is whether it is audible and whether you care. So ultimately it is up to you.

I have ripped all of my CDs as lossless to play them over my fancy home stereo. I would never want to listen to lossy files on it as they all tend to sound 'harsher' than CDs. For my iPod, however, I often do use compressed files (the iPod audio is actually that bad ;-). AAC is considered to be a better algorithm than MP3, meaning that it is supposed to achieve better compression at the same quality level. I have not tested it extensively and it is likely subtle. There is extensive debate around all kinds of other formats, but to be honest I doubt you should care.

The bigger choice to make is the bit rate. On my iPod I carry around AAC 192/256 kbit/s files which is perfectly fine for casual on the go listening. I thought 128 kbit/s and below is really compromising quality, but I haven't bothered looking for the 'perfect' cut-off, something which will depend on the song anyway. There is enough heated debate going around on the Internet on this topic as well which you can dip into if you like.

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I skipped right past the bit rate selection for AAC earlier! Thanks for mentioning it because I went back to it and there it is. OK, I think that I will revert back to AAC for now, probably 192 or 256 bit rate but one question I have is the checkbox for VBR (do I allow? and what is the benefit?). But at least I can get the file sizes down and I feel comfortable with the "loss"... for now. When I get back to owning a nice fancy home system, I am sure I will re-rip in lossless. –  Electric Automation Sep 30 '09 at 2:58
My suggestion - check the VBR (variable bit rate) check box. Basically, not every song has the same amount of information. You can see this if you use apple lossless compression - the bitrate of each song is different: higher bitrate more information, lower bitrate less information. When you compress to a fixed bit rate with a lossy compression then the quality will (slightly) vary across songs. VBR ostensibly keeps quality constant and will compress to a lower bit rate if a particular song does not happen to have a lot of audio information –  chris laurens Sep 30 '09 at 3:12
Thanks for that VBR info. I see those large bit rates on the lossless. I'll have to re-rip what I've done and play with these settings more - but you've set me on a better path for my needs. Thanks! –  Electric Automation Sep 30 '09 at 3:25

Given a choice between AAC and MP3, I'd go with MP3 simply because of the broader hardware/software support.

On the subject of quality, LAME is likely the premier MP3 encoder these days, and while I don't actually know how it compares to whatever MP3 encoder is built into iTunes, I trust LAME to do a good job with whatever music I throw at it. Using it will involve some extra steps though, compared to just letting iTunes do everything.

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I may experiment with this as well. I dont mind the extra steps and wouldnt mind side-stepping iTunes. Unfortunately I need iTunes as I dont know any other way to get the music into the iPhone (aside from a jailbreak - which I wont be doing in the near future).. Thanks! –  Electric Automation Sep 30 '09 at 3:03
I used to use mp3 exclusively for that reason too, but I've noticed nowadays most things that play mp3 can play AAC too (Windows Mobile, car stereos etc) –  Matthew Lock Sep 30 '09 at 8:45
+! for MP3 for the near guaranteed compatibility with any hardware (or software) you may use. You never know what you may want to use in the future. –  Xantec Nov 3 '10 at 13:42

There are scientific studies that prove that MP3s above 256 kbit/s and AACs above 192 kbit/s are not distinguishable from the originals even with good audio equipment.
If a human ear can't distinguish the original from the compressed file, I don't care for the parts that were left out, so I don't deem lossless compression particularly useful except for archival purposes (remastering might have use for inaudible details).

As a side note, even the data on a CD is lossy: the 16 bit quantization means that any dynamic peaks over 100 dB can't be stored (the human ear can hear up to 120 dB) and the sample rate of 44.1 kHz means that any frequency above 22050 Hz can't be stored (the human ear can hear up to about 20 kHz (children) or 16 kHz (adults)) and anything above about 20 kHz is severely distorted by the aliasing-filter used in mastering. However, the limitations of the audio gear are usually far greater than the limitations of the format.

Technically, AACs are MP4 files. MP4 is the official successor to MP3, which sports better audio quality at the same bitrate or the same audio quality at lower bitrates. All lossy audio formats look for masking effects (you don't hear background details when the foreground is loud) and compress masked frequency/time-blocks. Usually, compression is done by downsampling (MP3/MP4) and quantization (MP4). Additionally, the file is entropy-encoded (basic file compression). The achieved audio quality is basically dependent on the masking detection algorithm (this is were LAME improved MP3). The file size is dependent on the compression method (this is were MP4 improves MP3).

Hence, I use AAC with 256 kbit/s just to be save. If you insist on using MP3 for compatibility reasons, you could step up to 320 kbit/s. Note that with some players, playback of MP3s uses less battery than playback of AACs.

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"and anything above about 20 kHz is severely distorted by the aliasing-filter used in mastering" this is a bit wrong. They would use a 20khz low pass filter on mastering to effectively block any frequencies about 20khz from entering the signal path –  Matthew Lock Sep 30 '09 at 8:47
They use a lowpass filter with a cutoff frequency at 20 kHz to reach something like -80 dB at the nyquist frequency at 22.05 kHz to prevent aliasing artifacts. This means that there has to be a very steep filter slope. Using long minimum-phase digital FIR-filters this is easily achievable. Of course, any filter distorts the original audio signal, since this is the very purpose of filtering. I don't see how my statement is wrong in that regard. –  bastibe Sep 30 '09 at 13:44
I have been re-ripping the music into AAC-256 and it sounds OK to me. I think what it was doing prior, which lead me to post the question, was AAC-128. I can definitely tell a difference. As far as hearing 16khz - not me.. In my mid 40's and on a good day I think the 13-14khz area is where lose it. Too many concerts and too many years of blasting music... Thanks for the info! –  Electric Automation Sep 30 '09 at 13:55

Regarding the ALAC lossless files being huge, the half-size claim is probably relative to either uncompressed files or other lossless formats. Any lossless format is still going to be very large compared to a lossy compression scheme like MP3, Ogg, AAC, etc.

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"What is the Best iTunes Audio Format to use during ripping from CD?"

If you're talking about the best in terms of quality, it's not subjective.

ALAC is the best - by definition, it's lossless.

Why people bother with mp3 these days I'll never know. It's not 1998 anymore people!

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Because the iPod isn't the only music player out there, and most others just don't read alac. –  Joel Coehoorn Nov 3 '10 at 13:34

Variable Bit Rate MP3s are your best bet. They will play on all hardware (unlike AAC/M4A) and they are small enough. Hard disks are cheap, re-ripping your CDs takes time. At high enough quality, most people can't tell the difference between MP3s, AACs or CDs.

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Even though I personally use VBR MP3s, your statement that they play on all hardware is not entirely correct. Some older mp3 players don't understand VBR -- although I've only ever had problems with a couple files I didn't encode myself on my very old iPod mini. –  patrickvacek Nov 20 '13 at 14:44

I have had discussions with the engineers who worked on iTunes and AAC. These are people I know, who say that people shouldn't be able to hear the difference between a bit rate of 224 and anything higher (including CDs). At least one of these guys has incredible hearing. (MP3 is a different matter.) (They actually said 208 would likely be indistinguishable from CDs, but allow for certain passages in some very high quality recordings of pianos, hence 224.)

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Have you considered using Ogg Vorbis or FLAC? Why use proprietary codecs, if better (!) open alternatives are available?

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There is no absolute better. Hardware/software support for FLAC is not nearly as prevalent as MP3 or AAC support. If his player won't take FLAC, then any other benefits are irrelevant. –  Rich Homolka Mar 15 '11 at 20:30

I can definitely tell the difference between a 256 kbps file and the same file at 320 kbps (AAC format)... The sound range is far more dynamic at 320 kbps than at 256 kbps. I no longer buy songs off iTunes because the audio quality just is not there, they only have songs available at 256 kbps. I listen to extreme metal and so with lower bit rates I can hear auditory distortion on the very low and very high-range sounds. 128 kbps is blasphemy!

I now only buy CD's or I download music at 320 kbps. I have yet to test ALAC bit rates though, I'll get back on that one.

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