Audio formats

SebastianD9909 / Wikimedia Commons

Digital audio file formats come in four groups:

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. 

Uncompressed formats have the largest file sizes given equal lengths of 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. They can “lose” some of the data by removing  some of the 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, 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.
  • 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.

More  

What’s the difference between file formats?  Izotope,  2019