SebastianD9909 / Wikimedia Commons
Digital audio file formats come in four groups:
Original (or ‘native’) to your application, for example, Audacity’s .aup or Adobe Audition’s .sesx. The first can only be opened in Audacity, the second, only in Audition. (Other original formats include MS Word’s .docx, Excel’s .xlsx, Photoshop .psd, etc).
Uncompressed formats have the largest file sizes given equal lengths of recorded time. They include .wav formats for Windows PC and .aiff for MacOS. These days, Mac and PC platforms are able to handle both formats.
Compressed non-lossy audio formats are smaller size but have the same information. Formats include WavPack and MPEG 4. Typically these files are half the size of uncompressed formats like .wav.
Lossy audio formats are even smaller. Like .jpg image formats, lossy audio formats can “lose” some of the data by removing audio information. Lossy formats include ACC (for iTunes, aka m4a) along with MP3, or MPEG Layer 3, the most common sound file format in use. (The Moving Picture Experts Group is a working group of the International Standards Organization).
To repeat, you’ll probably work with these three formats most of the time:
- WAV – a non-lossy format, around 10 MB / minute, similar to the way you might use a non-lossy format like TIFF for digital images. NOT for podcasting or web browsers.
- MP3 – a lossy, compressible format that removes some data like JPG images. OK for podcasting.
- Note from Wikipedia audio formats pages: The combination of small size and acceptable fidelity led to a boom in the distribution of music over the Internet in the late 1990s, with MP3 serving as an enabling technology at a time when bandwidth and storage were still at a premium.
- The MP3 format soon became associated with controversies surrounding copyright infringement, music piracy, and the file sharing services MP3.com and Napster, among others. With the advent of portable media players (including “MP3 players”), a product category also including smartphones, MP3 support became near-universal and it remains a de facto standard for digital audio despite the creation of newer coding formats such as AAC.
- AAC (or M4a) – also a lossy, compressible format with better quality for the same bit rate as MP3. This is the best format for podcasting.
Why use Lossy Audio Formats?
So why would we want a file in which information is lost? First, to reduce the size, and secondly, to use a format adapted to the internet.
Size: File size used to be a major issue for online downloads and exchanges due to limited internet bandwidth. Generally, a non-compressible .wav file is 10 times larger than a compressed, lossy mp3 file.
In the 2020s it is still significant, but with high internet speeds, not quite as important.
Internet exchanges: Not only are lossy files smaller for the same relative quality, the formats are adapted for internet playing and exchanges. Not long ago it wasn’t possible to play a .wav file via direct download, but now .wav players are built into most browsers.
further
What’s the difference between file formats? Izotope, 2019.
Audio file formats, Wikipedia
Timeline of audio formats, from 1805, Wikipedia