Audio files come in all types and sizes. And while we may all be familiar with MP3, what about AAC, FLAC, OGG, or WMA? Why do so many standards exist? Which ones should you care about and which ones can you ignore?
It’s actually quite simple once you realize that all audio formats fall into three major categories. Once you know which category you want, all you have to do is pick the format within that category that best suits your needs.
Uncompressed Audio Formats
Uncompressed audio is exactly what it sounds like: real sound waves that have been captured and converted to digital format without any further processing. As a result, uncompressed audio files tend to be the most accurate but take up a LOT of disk space — about 34 MB per minute for 24-bit 96 KHz stereo.
PCM stands for Pulse-Code Modulation, a digital representation of raw analog audio signals. Analog sounds exist as waveforms, and in order to convert a waveform into digital bits, the sound must be sampled and recorded at certain intervals (or pulses).
As such, this digital audio format has a “sampling rate” (how often a sample is made) and a “bit depth” (how many bits are used to represent each sample). There is no compression involved. The digital recording is a close-to-exact representation of the analog sound.
PCM is the most common audio format used in CDs and DVDs. There is a subtype of PCM called Linear Pulse-Code Modulation, where samples are taken at linear intervals. LPCM is the most common form of PCM, which is why the two terms are almost interchangeable at this point.
WAV stands for Waveform Audio File Format (also called Audio for Windows at some point but not anymore). It’s a standard that was developed by Microsoft and IBM back in 1991.
A lot of people assume that all WAV files are uncompressed audio files, but that’s not exactly true. WAV is actually just a Windows container for audio formats. This means that a WAV file can contain compressed audio, but it’s rarely used for that.
Most WAV files contain uncompressed audio in PCM format. The WAV file is just a wrapper for the PCM encoding, making it more suitable for use on Windows systems. However, Mac systems can usually open WAV files without any issues.
AIFF stands for Audio Interchange File Format. Similar to how Microsoft and IBM developed WAV for Windows, AIFF is a format that was developed by Apple for Mac systems back in 1988.
Also similar to WAV files, AIFF files can contain multiple kinds of audio. For example, there is a compressed version called AIFF-C and another version called Apple Loops which is used by GarageBand and Logic Audio — and they all use the same AIFF extension.
Most AIFF files contain uncompressed audio in PCM format. The AIFF file is just a wrapper for the PCM encoding, making it more suitable for use on Mac systems. However, Windows systems can usually open AIFF files without any issues.
Lossy Compressed Audio Formats
Lossy compression is a form of compression that loses data during the compression process. In the context of audio, that means sacrificing quality and fidelity for file size. The good news is that, in most cases, you won’t be able to hear the difference.
However, if the audio gets compressed too much or too often, you’ll start hearing artifacts and other weirdnesses that become more and more noticeable.
MP3 stands for MPEG-1 Audio Layer 3. It was released back in 1993 and quickly exploded in popularity, eventually becoming the most popular audio format in the world for music files. There’s a reason why we have “MP3 players” but not “OGG players”…
The main pursuit of MP3 is to cut out all of the sound data that exists beyond the hearing range of most normal people and to reduce the quality of sounds that aren’t as easy to hear, and then to compress all other audio data as efficiently as possible.
Nearly every digital device in the world with audio playback can read and play MP3 files, whether we’re talking about PCs, Macs, Androids, iPhones, Smart TVs, or whatever else. When you need universal, MP3 will never let you down.
Note that MP3 is not the same as MP4, even though their similar names might suggest otherwise.
AAC stands for Advanced Audio Coding. It was developed in 1997 as the successor to MP3, and while it did catch on as a popular format to use, it never really overtook MP3 as the most popular for everyday music and recording.
The compression algorithm used by AAC is much more advanced and technical than MP3, so when you compare a particular recording in MP3 and AAC formats at the same bitrate, the AAC one will generally have better sound quality.
Again, even though MP3 is more of a household format, AAC is widely used today. In fact, it’s the standard audio compression method used by YouTube, Android, iOS, iTunes, later Nintendo portables, and later PlayStations.
OGG doesn’t stand for anything. Actually, it’s not even a compression format. OGG is a multimedia container that can hold all kinds of compression formats, but is most commonly used to hold Vorbis files — hence why these audio files are called Ogg Vorbis files.
Vorbis was first released in 2000 and grew in popularity due to two reasons: first, it adheres to the principles of open source software, and second, it performs significantly better than most other lossy compression formats (i.e. produces a smaller file size for equivalent audio quality).
MP3 and AAC have such strong footholds that OGG has had a hard time breaking into the spotlight — not many devices support it natively — but it’s getting better with time. For now, it’s mostly used by hardcore proponents of open software.
WMA stands for Windows Media Audio. It was first released in 1999 and has gone through several evolutions since then, all while keeping the same WMA name and extension. As you might expect, it’s a proprietary format created by Microsoft.
Not unlike AAC and OGG, WMA was meant to address some of the flaws in the MP3 compression method — and as such, WMA’s approach to compression is pretty similar to AAC and OGG. In other words, in terms of objective quality, WMA is better than MP3.
But since WMA is proprietary, not many devices and platforms support it. It also doesn’t offer any real benefits over AAC or OGG, so in most cases when MP3 isn’t good enough, it’s simply more practical to go with one of those two instead.
Lossless Compressed Audio Formats
On the other side of the coin is lossless compression, which is a method that reduces file size without any loss in quality between the original source file and the resulting file. The downside is that lossless compression isn’t as efficient as lossy compression, meaning equivalent files can be 2x to 5x larger.
This is obviously much harder to do well, but there are a few good formats for this. And don’t confuse lossless compression with high-resolution audio (which is most likely a scam anyway).
FLAC stands for Free Lossless Audio Codec. A bit on the nose maybe, but it has quickly become one of the most popular lossless formats available since its introduction in 2001.
What’s nice is that FLAC can compress an original source file by up to 60% without losing a single bit of data. What’s even nicer is that FLAC is an open source and royalty-free format rather than a proprietary one, so it doesn’t impose any intellectual property constraints.
FLAC is supported by most major programs and devices and is the main alternative to MP3 for CD audio. With it, you basically get the full quality of raw uncompressed audio in half the file size — what’s not to love about it?
ALAC stands for Apple Lossless Audio Codec. It was developed and launched in 2004 as a proprietary format but eventually became open source and royalty-free in 2011. ALAC is sometimes referred to as Apple Lossless.
While ALAC is good, it’s slightly less efficient than FLAC when it comes to compression. However, Apple users don’t really have a choice between the two because iTunes and iOS both provide native support for ALAC and no support at all for FLAC.
WMA stands for Windows Media Audio. We covered it above in the lossy compression section, but we mention it here because there’s a lossless alternative called WMA Lossless that uses the same extension. Confusing, I know.
Compared to FLAC and ALAC, WMA Lossless is the worst in terms of compression efficiency but only slightly. It’s a proprietary format so it’s no good for fans of open source software, but it is supported natively on both Windows and Mac systems.
The biggest issue with WMA Lossless is the limited hardware support. If you want lossless audio across multiple devices, you should stick with FLAC unless all of your devices are of the Windows variety.
So Which Format Should You Use?
For most people, the decision is actually pretty easy:
- If you’re capturing and editing raw audio, use an uncompressed format. This way you’re working with the truest quality of audio possible. When you’re done, you can export to a compressed format.
- If you’re listening to music and want faithful audio representation, use lossless audio compression. This is why audiophiles always scramble for FLAC albums over MP3 albums. Note that you’ll need more storage space for these.
- If you’re okay with “good enough” music quality, if your audio file doesn’t have any music, or if you need to conserve disk space, use lossy audio compression. Most people actually can’t hear the difference between lossy and lossless compression.
For those who want utmost quality in their music playback, note that high-quality audio files won’t matter if your playback device can’t faithfully recreate those sounds. Meaning, you need to have good quality speakers or good quality headphones!
Are you an audiophile? What kind of audio formats do you use most often? Got any other tips for picking the right format in the right situation? Share with us in the comments!