All about file formats and codecs

Audio file formats are different forms of compression, all differing in quality the listener will experience on the receiving end. Programs used to process audio files are called audio codecs, which compress audio for transmitting data and decompress it when the data is received.

The speed of audio codecs is measured in bitrate (kbps), or thousands of bits processed per second. This number can vary even within the same audio format. Typically, the lower the bitrate, the smaller the audio file. It can come at the cost of more data lost in audio compression, which reduces the sound quality. 

Other factors include bit depth and sample rate. Sample rate is the number of samples—sound, or the signal amplitude—per second. The bit depth is the number of bits per sample. The higher the bit depth, the fuller or louder the sound will be. 

Understanding who your listeners are and where they will listen is important when choosing your file format. You want to balance your audience’s ability to easily access your audio with the sound quality they get when they listen.

Compressed vs. uncompressed: Understanding audio file formats

Each audio format is either compressed or uncompressed. Uncompressed audio, which includes WAV, AIFF, and DSD file types, means the data remains the same size from the transmission to the receiving end.

Compressed audio means that portions of data are removed from the recording to make it smaller and easier to store or share. Compressed audio is broken down into two different formats. 

• Lossless audio formats. These files will ensure the sound quality is intact because it decompresses files back to their original size. They’re usually much larger compared to lossy formats. File types include M4A, MQA, WMA, FLAC and ALAC.
• Lossy audio formats. Data will be lost in the transmission with lossy audio formats. Once the audio is compressed, it won’t decompress back to the original size. Some quality may be lost, or degraded, but the files tend to be smaller. File types include MP3, AAC, and Ogg Vorbis (OGG).

🧠 Learn: What is an audio file converter and how do you use it?

11 most common audio file formats

1. AAC

The AAC format, short for Advanced Audio Coding, is similar to MP3 and is generally better for streaming over mobile devices. AAC provides enhanced audio quality even at the same bit rate. Due to its versatility, it's the default audio format for many devices, such as iPhones and Android phones, and apps like Apple Music (formerly iTunes) and YouTube. 

2. AIFF

Apple created the Audio Interchange File Format, which is similar to the more well-known WAV file. AIFF retains all of the original data and tends to be a larger file size. 

Professionals in the music industry might use AIFF files for master recordings before converting to other formats for distribution. However, AIFF files don’t have time codes, so they aren’t necessarily helpful in mixing and editing. You can play AIFF files on Macs and PCs. 

3. ALAC

This format is Apple’s Lossless Audio Codec (similar to FLAC) and only works on Apple devices. When decompressed, the audio will be identical to the source material. 

Because it retains all the original audio data, many audiophiles and music enthusiasts use ALAC. It offers a smaller file size than uncompressed formats like WAV or AIFF while maintaining the same sound quality.

If you want to archive an audio collection, ALAC is a good option. It ensures that even if the original physical sources (like CDs) are lost or damaged, the digital files retain the full audio quality.

4. M4A

An M4A file extension is for audio files encoded with advanced audio coding (AAC), which is lossy compression. It's part of the MPEG-4 multimedia standard and offers better sound quality than MP3 files at the same bitrate. 

You'll often find M4A files in digital storefronts and streaming platforms. It’s also a popular podcast file format because it offers good quality at a smaller file size. 

5. DSD

The Direct Stream Digital is a high-quality single-bit format—which means larger file sizes. They’re usually found on Super Audio CDs and played on high-end audio systems. DSD isn’t appropriate for streaming. 

The DSD uses 1-bit samples at 2.8224 MHz, 64 times the CD's 44.1 kHz sample rate. Because of its 1-bit depth, DSD recordings can only represent two amplitude values, but the high sampling rate lets it reproduce audio frequencies up to half the sampling rate accurately.

DSD was mainly used for SACDs, which were aimed at providing higher sound quality than traditional CDs. Some specialty stores sell DSD files, but only to cater to audiophiles who want high-resolution music.

6. FLAC

The Free Lossless Audio Codec is an uncompressed, royalty-free codec that also stores metadata. Most use the format to download and store high-resolution audio files.

FLAC is open-source, so its source code is available for free, and you can use it without licensing fees. Unlike lossy codecs like MP3 and AAC, which discard audio data to achieve smaller file sizes, FLAC retains all the audio data from the original source.

The compression ratio for FLAC depends on the type of music or audio, but typically it ranges from 30% to 50%. This means that a FLAC file will be much smaller than its equivalent raw WAV or AIFF file but bigger than a lossy MP3 or AAC file of the same audio.

7. MP4

This multimedia container format supports video, audio, subtitles, images, and even text. It’s based on Apple QuickTime, but has been standardized as ISO/IEC 14496-14 by the Moving Picture Experts Group.

Many sites like YouTube, Vimeo, and many others use MP4 for their video uploads due to its high compression and good quality. It's a great format for storing movies, TV shows, music videos, and other video content.

Many devices can play MP4 files, including smartphones, tablets, computers, and televisions. Given its wide acceptance, many video editing software tools support MP4, making it easier for creators to work with their content.

8. MP3

MP3 is a popular lossy compression audio format that offers small file sizes but at the cost of potentially poor sound quality. It’s a popular choice for media players and storing files on mobile devices. 

Since MP3 files are smaller, transferring them between devices and downloading them from the internet is easier. MP3 can also be played on a wide variety of devices, including smartphones, computers, tablets, and standalone MP3 players.

9. OGG

The name "OGG" comes from "ogging," a term from the video game "Netrek." However, over time, OGG has come to be seen less as an acronym and more as a brand or umbrella term for the various media formats developed by Xiph.Org.

Ogg Vorbis is similar to MP3s and AACs, and is an open-source codec. Spotify uses this in their streaming services, streaming at 160kbps for the free version and 320kbps for the paid version. The OGG container isn’t restricted to any specific codec or format and can contain streams encoded with various codecs, such as Theora for video or Vorbis for audio.

OGG is mainly used to store audio files compressed with the Vorbis codec, which is why people call them "OGG Vorbis". Vorbis offers similar audio quality to MP3 at lower bit rates. You can also store video streams with OGG, usually using the Theora codec. It's less common than audio, though.

10. WAV

Microsoft and IBM developed the Waveform Audio File Format (WAV) for storing audio bitstreams on Windows PCs. It’s based on the Resource Interchange File Format (RIFF) to store both compressed and uncompressed audio files. WAV files use the Pulse-Code Modulation (PCM) format to store uncompressed audio data, which you can encode onto audio CDs.

Suppose you're a music producer working on a new track. When recording instruments and vocals, you'd prefer the WAV format to ensure you're getting the best quality recordings. 

After the recording is done, you mix and master the track using audio editing software. To prevent quality degradation, the audio remains in WAV format throughout the whole thing. You might then convert the track to a more compressed format, like MP3, for distribution or streaming, but keep the original WAV files because they're the purest, highest quality version.

11. PCM

Pulse Code Modulation is a method used to convert analog audio signals into digital files. 

The analog signal’s amplitude is measured (or "sampled") periodically at uniform intervals. Each of these sampled values is then rounded to the nearest value within a set of predetermined levels. Then the quantized values are then represented in binary form.

PCM was popular for CDs, but today it’s used in telecommunications and music production to transmit high resolution audio and video. 

How to choose the right audio file format

Choosing the right format depends on how you’re using your audio. In most cases, you’ll want to choose the most popular audio formats, especially if you want your files to be as accessible as possible. 

Plus, popular audio editing programs don’t support some formats, so keep that in mind if you don’t have specialized editing equipment.

A few scenarios can help you decide what type of audio file format to use:

• Uncompressed audio formats. You’re an audio professional who’s planning on editing audio, like for a podcast. Choosing either AIFF, PCM, or WAV allows you to export a file that has high-quality audio and is easy to distribute. 
• Lossless formats. You’re an audiophile who wants to listen to high fidelity music with the best audio quality you can find. WMA, M4A, and FLAC files allow you to keep the data in the original recording but don’t require as much storage space. 
• Lossy formats. You’re hoping to share your audio files online and save disk space in the process. Using AAC, OGG, or MP3 formats will result in some loss in audio quality, but you’re not someone who can tell the difference, nor will the people you share your files with.

You want to choose an audio format that helps you achieve the kind of audio quality you need. Don’t worry about getting super high-quality audio files if it’s not essential because large files are cumbersome to convert, manage, and share.

Manage and edit your audio files in seconds

Choosing the best audio file is only the start of any podcast or video. What really matters is how you edit the files and mix them together to make voices come through clear as day. You can get this effect using Descript, the best audio editing software for creators and marketers. 

Whether you’re creating a podcast or editing a movie, use Descript to:

• Edit audio, remove silence, and add crossfades and effects to your projects.
• Remove filler words like "um," "uh," and "you know" with just one click.
• Create and edit content using an AI model of your voice. 
• Make your dialogue sound clear and hi-res with Studio Sound. 

Thousands of popular podcasts like Planet Money and Freakonomics Radio use Descript to perfect their episodes. Want to join them? Take a free tour today. 

Audio format FAQs

What is the best audio format for sound quality?

The best audio formats for sound quality are uncompressed or lossless compression files—think WAV, FLAC, and M4A. That’s because these formats retain the original sound quality, though you’ll have to put up with the fact these files will be large.

What audio file format is best for use on the web?

The best audio file formats to use on the web are MP3s and MP4s. They’re most likely to be compatible with most web browsers such as Google Chrome and Firefox. Other formats that most browsers support include AAC, OGG, and WAV, though they tend to have large file sizes.

What is the most popular audio format?

The most popular digital audio format is MP3. It’s one of the easiest file types to download and share, and it doesn’t take up too much disk space compared to other file formats. 

In addition, you can create MP3s with different bitrates, which can alter your file’s size and quality. Due to its flexibility, many devices play MP3 files making it one of the main ways to share audio online.