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Audio file formats: Lossy, lossless, compressed, uncompressed

The countless audio formats available in the market might confuse even the most experienced musicians, who must be aware of all the requirements of streaming platforms, music websites, and social media before uploading or sharing audio content.

This is no trivial task, and getting the audio format wrong might lead to missing opportunities or time-consuming adjustments that’ll slow down your workflow considerably.

That’s why I decided to focus this article on the most popular audio formats, their purpose, and how to identify when you should use one or the other.

Let’s dive in!

About the author

I’ve worked in the music industry most of my adult life and have often received songs in the wrong audio format: producers sending me their beats as an MP3 file via WhatsApp, musicians sending me 2 GB of uncompressed songs just to “get an idea of their sound.” The list is endless. As a music producer and audio engineer, I understand the importance of using the right audio formats in all situations, whether you’re uploading your content online or sharing it with others.

Compressed vs uncompressed audio formats

Let’s start with some distinctions: audio formats can be divided into two main categories, compressed and uncompressed. In turn, compressed audio formats feature two sub-categories: lossy and lossless, which we’ll discuss later on.

Uncompressed audio formats are files in which no data compression has been applied. Meaning: this file will contain the raw audio in its original size, with a level of accuracy that’s defined by the sample rate and bit depth used during the recording session. More on that later.

using uncompressed audio in music production
Image: N. Yanyong

Audio engineers use uncompressed audio formats to mix and master music, and if you’re a musician, you want to have your recordings in this format. You can compress an uncompressed file, but you can’t “uncompress” a compressed file.

The downside of uncompressed audio formats is, you might guess, their size. They’re by far the biggest audio files, and you can easily reach 10 MB per minute of music, so it wouldn’t take long to fill up your hard drive with uncompressed tracks.

Compressed audio formats are a great solution to save disk space, and a smaller file size doesn’t necessarily mean a huge quality loss.

Lossless vs lossy audio formats

The name says it all: lossless audio is music stored in a format that doesn’t sacrifice audio quality and yet manages to make the file much smaller than its uncompressed counterpart.

They do so thanks to an efficient compression algorithm that decodes the data included in an uncompressed file and makes it smaller without audible differences.

Lossy formats can be even smaller than lossless ones, but that comes with a price: so much compression causes some critical information to be removed, causing the audio to lose quality.

listening to lossy audio via portable device
Image: Viktor Forgacs

Lossy formats were extremely popular back in the early 2000s, when file sharing took the music industry by storm, and still today, many stores like Bandcamp and Beatport allow users to download MP3 files.

Sample rate and bit depth

Alright, so these are rather complex topics, and you might not even need to know what they mean unless you work with audio. However, I’m going to briefly explain what sample rate and bit depth are as they define the quality of an audio file.

When you record music digitally, the original soundwave is converted to data which your computer, tablet, or smartphone can decipher and recognise as the sound you just recorded.

Essentially, what you’re hearing is a sound reconstructed digitally and translated into bits through a method called pulse code modulation or PCM.

The accuracy of this representation is defined by the sample rate and bit depth.

The sample rate defines how many “snapshots” of the waveform are taken to create the digital signal. 44.1 kHz is the standard rate for CDs, but you can go much higher than that with modern recording gear (and I’d recommend you do so if you’re a producer: the more information you have, the better).

The bit depth determines the number of bits available to define the amplitude values of a soundwave. The more bits we have, the more accurate our digital representation of the sound will be.

16, 24, and 32-bit are standard bit-depth resolutions for professional audio recording.

These are the most common audio file formats:

MP3

  • Extension: .mp3.
  • Type: lossy compressed.
  • Resolution: 16 bit / 320 kbps.
  • Ideal for: casual listening, sharing online and storing music.

MP3 files are ideal when disk space is limited and audio accuracy is not crucial. They’ve been one of the most popular audio formats since the dawn of file sharing when data was scarce and downloading 300 MB would take days.

Still, MP3 provides good-quality audio for casual listening and won’t fill up your disk space easily.

  • Small file size, versatile.
  • Other files provide better quality.

WAV/AIFF

  • Extension: .wav, .aiff.
  • Type: lossless uncompressed.
  • Resolution: 16 bit / 44.1 kHz (standard CD quality).
  • Ideal for: music production, high-fidelity audio.

If you’re a music producer, you’ll be using these audio formats a lot. Both WAV and its Apple counterpart, AIFF files, don’t compress audio in any way, meaning you’ll get a file with all the information stored during the recording session.

The downside is the file size, which is huge when compared to lossy and even lossless files. Nevertheless, WAV and AIFF formats are the most common files when recording, mixing, and producing music.

  • Highest possible quality.
  • File size.

AAC

  • Extension: .aac.
  • Type: lossy compressed.
  • Resolution: 16 bit / 256 kbps.
  • Ideal for: casual listening, sharing online and storing music.

AAC is essentially a better version of the MP3 that never managed to become as popular as its predecessor.

AAC files are accepted by most music platforms and playable by all devices, and its well-designed algorithm allows better compression and less quality loss than the MP3.

If you want to share small-size audio files in the best possible quality, AAC is a valid option.

  • Good audio quality despite the small file size.
  • Still a lossy format, with minimal differences when compared to MP3 quality.

Ogg Vorbis

  • Extension: .ogg.
  • Type: lossy compressed.
  • Resolution: 16 bit / 320 kbps.
  • Ideal for: casual listening, sharing online and storing music.

Vorbis is the open-source competitor of MP3 and AAC and offers excellent audio quality considering its small size.

The downside is that most devices will require dedicated software to play these files, as they don’t natively support the format.

Despite that, the quality of Vorbis’ file is beyond doubt, which is why Spotify chose it to stream its music.

  • Great quality for a lossy file, small size, open source.
  • Not widely used, compatibility issues.

FLAC/ALAC

  • Extension: .flac, .alac.
  • Type: lossless compressed.
  • Resolution: 32 bit / 192 kHz
  • Ideal for: critical listening, sharing high-quality files.

FLAC and its Apple counterpart ALAC are audio formats that provide outstanding sound resolution and no audible quality loss in a file half the size compared to the uncompressed WAV and AIFF formats.

FLAC is open source and works on all devices (except iTunes) without needing third-party apps, making it the most popular option for sharing and uploading lossless compressed files.

Similarly, ALAC is great if you need to share large files with other Mac users.

  • Smaller size than uncompressed files with the same audio quality.

Final thoughts

Now you know everything there is to know about audio formats!

If you’re a musician, it’s crucial you keep a copy of your songs as uncompressed, high-quality files, either WAV or AIFF.

Lossless formats like FLAC and ALAC are great for uploading your music on SoundCloud and sharing it with collaborators, labels, and magazines.

Lossy files are useful when you want to save disk space and internet data, and a good-quality MP3 file can definitely satisfy the needs of casual listeners.

Good luck, and stay creative!

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