There are endless file formats to consider before ripping CDs. Some of the popular formats are WAV and AIFF (uncompressed), and FLAC, WMA, ALAC, APE, and WavPack (lossless compression). The decision about what format to use can be made by considering disk space and interoperability.
Please note: I am certainly not the Minister of Information and these statements should be considered my opinion based upon my own knowledge, research, and experience.
The quickest path to determine the correct format for your situation is this:
1. Can you afford the disk space required to use uncompressed formats?
a. If yes, my answer is AIFF.
b. If no, proceed to number two.
2. What operating system(s) are you gong to use?
a. If Windows only my answer is FLAC.
b. If Mac OS X only my answer is ALAC.
c. If Windows and Mac OS X my answer is ALAC.
Why These Formats?
1. Uncompressed AIFF
Uncompressed - Question number one is all about compressed versus uncompressed formats. If you can afford the disk space I see no reason to use a compressed format. Right now one terabyte is literally one-hundred dollars at NewEgg. Even with the current economic recession (Jan, 2009) this is reasonable. There is currently much debate about whether or not there is an audible difference between compressed and uncompressed formats. This fact alone is reason enough to avoid any type of compression. As with all other audiophile "dilemmas" this one is likely to go on for the foreseeable future. The whole issue can be avoided by selecting an uncompressed file format. In my opinion using compression means one has to rule out the possibility that compressed formats might later be found to have unforeseen issues that uncompressed formats do not have. Is it likely to happen? Absolutely not, but why take a chance you don't have to take even if it is minute?
Almost everyone agrees that lossless compression is lossless. But what exactly does that mean? To many it means that lossless compressed files are exactly the same as uncompressed files from the time they are ripped to the time they hit the DAC during playback. In my opinion lossless files are lossless in terms of compressing them as a method of storage and transport. One can convert an uncompressed file to a lossless file and back again all day and night without any loss of data. The potential issue arises when compressed files must be uncompressed in real time during playback. In my opinion there is no reason to compress a file that must be uncompressed to be played back. One often used comparison is between data files being compressed with WinZip and audio files being compressed with a lossless codec. I think this is a good comparison, but it leads me to a different conclusion than many people who use the analogy. I too agree that a word document compressed with WinZip will be the same word document whether I zip it and unzip it one or one-hundred times. After all lossless is lossless. Here is where my opinion differs and it involves real time uncompressing of data/music. If you were to losslessly compress 20,000 word documents & spreadsheets (roughly the same as compressing 2000 albums with 10 tracks each). It is very likely you would experience some hiccups upon opening the files every once in a while. The data certainly won't change without some kind of corruption, but it's very likely your computer will "stutter" a few times opening thousands of zipped documents and spreadsheets. Unzipping a document is one of the easiest tasks a computer is capable of doing. This is similar to playing music as it too is rather simple for a computer to handle. I look at it this way. Audiophiles often spend thousands of dollars for an extra .01% improvement in their system. So, I see know reason to use any compression at all. It's all about managing risk. Uncompressed AIFF and WAV eliminate the risk of decompression errors in real-time. Granted the chances of hearing something wrong with a compressed file are minuscule or arguably nonexistent, but audiophiles are into reducing minuscule risks.
Format longevity is another reason I elect to avoid compression. Uncompressed formats have been around for decades and I'm betting they'll be supported for the foreseeable future. WAV was developed for Windows 3.1 around 1991 by IBM and Microsoft. AIFF was developed for the most part by Apple in 1988. Compressed formats haven't been used for nearly as long. FLAC was first used byXiphophorus in 2003 while Apple Lossless was first introduced on April 28, 2004. The comparative youthfulness of compressed formats is certainly no indication of their validity or performance. Rather "newer" technologies tend to have many competitors that lead to format wars. This can lead to one, two, or many formats eventually winning out. In the music server world this means that since applications only support a limited number of formats there will be certain compression schemes dropped or added by applications sometime in the near future. Another argument can be made against uncompressed formats because they are getting long in the tooth. This is certainly a concern, but not one I lose sleep over. Dropping AIFF and/or WAV support by any application doesn't seem likely. Supporting these uncompressed formats has been done "forever" and does not require a company to reinvent the wheel to continue supporting them.
AIFF - The two popular uncompressed formats are WAV and AIFF. I use AIFF because it natively supports embedded meta-data tagging and album art. WAV files in general don't have embedded meta-data or album art. In addition WAV files can be limited in size to between two and four GB. This may not seem like a real world limitation but 24/192 music can easily reach this limitation. Sonically I've never heard of anyone identifying differences between WAV and AIFF.
2. Lossless Compressed FLAC and ALAC
Windows - Lossless Compressed FLAC
For Windows users who either cannot afford enough disk space or elect not to purchase enough disk space for uncompressed music I recommend FLAC. Free Lossless Audio Codec is the best lossless compression option on the Windows platform for a few reasons. FLAC supports excellent meta-data tagging and album art. I recommend FLAC over Windows Media Lossless (WMA) because FLAC is open source and the most widely supported lossless codec. FLAC can be used with MediaMonkey or other popular players that allow bypassing the dreaded Windows KMixer. Windows Media Player does not have native support for FLAC, but I don't consider Windows Media Player to be a true audiophile application.
Mac OS X - Apple Lossless Audio Codec (ALAC)
iTunes is the gold standard playback application on Mac OS X. Unfortunately iTunes does not support FLAC natively and the enabling plugins / applications like Fluke are less than flawless. I personally don't use Fluke as I find it a bigger headache than it's worth. Thus ALAC is my recommended lossless compression scheme for OS X. Full meta-data tagging support and album art. Since it was developed by Apple themselves there are very few issues with ALAC. File sizes are reduced between 40% and 60%. This also helps people synchronizing iPods with little available space. Whenever the Apple Airport Express is used to stream music all files are actually converted to ALAC in the process. So, starting with ALAC may be a good thing in this situation.
Windows and Mac OS X Interoperability
Audiophiles that require interoperability between Mac OS X and Windows platforms have more options by selecting ALAC. As I said earlier playing FLAC on Mac is a non-starter for me. Playing ALAC on a PC is much easier. Applications such as JRiver and WinAmp support ALAC. While the files will play on these Windows applications there are issues with meta-data tagging. Cross platform interoperability without issues is still very elusive. Even cross application interoperability is currently less than good.
As I made clear in this article I am definitely not proposing the one and only file format, but my preference is for uncompressed AIFF files. This is my recommendation for many reasons, among them avoidance of ambiguity, reduction of risk, and format longevity. In addition, this whole discussion may be moot when multi-terabyte drives are twenty-five dollars. When disk space is no longer a concern data compression is no longer a concern in my opinion. If I had my wish I would select a file format somewhere between AIFF and FLAC. Uncompressed AIFF as open source as FLAC would be pretty nice. Even though lossless compression is not my favorite thing I clearly understand that it works fabulous for a large percentage of music lovers. Whatever works for you is OK with me. There is no right or wrong answer. If you're on the fence over what format to select you're in luck. Trying AIFF, FLAC, and ALAC is totally free and allows you to decide for yourself. In an industry where one can't walk into retail store without dropping a couple grand there is something to be said about a free exercise involving high-end audio anything.