What is the best file format/bit rate to rip tracks from a CD into iTunes? [closed]

Solution 1:

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.

Solution 2:

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.

Solution 3:

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.

Solution 4:

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