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The 4 Audio File Types Every Podcaster Should Know

Defining the differences between MP3, WAV, and other common digital audio files.

Digital audio recording began in the 70s and really took off in the early 80s with the release of the digital audio compact disc (CD). The quality of those digital files was subpar to say the least. With our now seemingly endless storage capabilities and extremely fast processors, we're able to create near perfect digital representations of analog sound. There are many different forms of digital audio files out there today that all serve a unique purpose. Outlined below are 4 of the most common digital audio files used today that every podcaster should be familiar with.


A common question I get asked is, What file type should I send for editing? We'll get to that answer later on in this article. Let's first review some foundational terms related to digital audio to help us understand the differences between file types.


A Digital Audio File is a collection of binary data created from a series of snapshot measurements (samples) of a sound wave's frequencies and amplitude over time. The amount of data captured in a single snapshot is typically determined by sample rate and bit depth.


Sample Rate determines the amount of times a sound is sampled per second. This will determine the range of frequencies captured, measured in kilohertz (kHz).


Bit Depth sets an amplitude scale for each snapshot. Higher bit depths offer more dynamic range. It's also thought of as the resolution of each snapshot. The larger the bit depth, the more accurate the sample.


Bit Rate is the number of bits processed or transmitted per second, often measured in kilobits per second (kbps). The higher the bit rate, the higher the quality.


Uncompressed in digital audio refers to an unaltered copy or representation of a sound file.


Compressed in digital audio refers to a reduction of information in a sound file in order to reduce file size.


Lossless is a form of compression that involves no loss of information.


Lossy is a form of compression that permanently discards information in order to further reduce file size.


Now that we've covered a few of the terms used to classify and describe digital audio files, let's jump into the 4 file types you need to know.


1) MP3 (MPEG-1 Audio Layer III)


The MP3 file is by far the most well-known form of digital audio. After it's initial release in 1993, the MP3 file format quickly became a hit with it's ability to reduce file sizes by over 75% compared to CD-quality digital audio. MP3 compression works by reducing frequencies that extend beyond the hearing capabilities of humans. This data is permanently removed from the file during the MP3 compression process.


This file type is considered low quality compared to other digital audio formats. Even with that in mind, an MP3 file created at 320 kbps, which is the highest allowable bit rate setting, is practically indistinguishable from a CD-quality file to most listeners. This means that to the average listener, a full quality MP3 file sounds just as good and takes up a fraction of the space compared to an uncompressed file. A more noticeable degradation in audio quality occurs once you get down to around 128 kbps and below.


Main Uses:

  • Streaming & Downloading

  • Sharing (Email / Text)

Technical Details:

  • Filename Extension: .mp3

  • Compressed - Lossy

  • Typical Bit Rate: 96 - 320 kbps

  • Typical Sample Rate: 44.1 kHz


2) WAVE (WAV) - Waveform Audio File Format


Developed by IBM and Microsoft, the WAV file was designed to accurately represent analog audio in a digital format. This is done by using pulse-code modulation (PCM) to capture samples of an analog signal at uniform intervals.


Since this file type is an uncompressed, high-quality representation of analog audio signals, the file sizes can be extremely large. This makes it less ideal for streaming and sharing purposes. WAV files are the standard digital audio format used by audio professionals.


Main Uses:

  • High Resolution Recording

  • Editing, Mixing, & Mastering

  • High Resolution Downloads

Technical Details:

  • Filename Extension: .wav

  • Uncompressed - Lossless

  • Typical Bit Depth: 16-bit / 24-bit / 32-bit

  • Typical Sample Rate: 44.1 - 192 kHz


3) M4A - MPEG-4 Audio


M4A files are the file types used by iTunes. It's an audio only component of an MP4 file, which is a multimedia container that stores video and audio information. It was designed to be the successor to MP3 with an increase in quality while maintaining a small file size.


M4A files are commonly created using advanced audio coding (AAC), which is a form of lossy compression. M4A files encoded at the same bit rate as an MP3 have a higher-quality sound due to the AAC encoding process.


One drawback of this file type is the lack of compatibility. Not all hardware devices and software programs can open M4A files. This gives the MP3 file a slight edge over the higher-quality M4A.


Main Uses:

  • Streaming & Downloads

Technical Details:

  • Filename Extension: .m4a (audio only), .mp4

  • Compressed - Lossy

  • Typical Bit Rate: 128 - 320 kbps

  • Typical Sample Rate: 44.1 kHz


4) AIFF - Audio Interchange File Format


Similar to the WAV file, AIFF files are uncompressed. This format was developed by Apple in response to IBM's and Microsoft's WAV file. Other than the different filename extension, the two file types are identical.


Main Uses:

  • High Resolution Recording

  • Editing, Mixing, & Mastering

  • High Resolution Downloads

Technical Details:

  • Filename Extension: .aif, .aiff

  • Uncompressed - Lossless

  • Typical Bit Depth: 16-bit / 24-bit / 32-bit

  • Typical Sample Rate: 44.1 - 192 kHz

So, What file type do I send for editing?


Technically, you can send any of the above file types. Most editing softwares are able to convert these common formats into a form suitable for editing, which is typically WAV. So, if you ask for my preference, I'll answer WAV files every time. Full quality, uncompressed files is ideally what you want to work with during any form of post production. The quality and file size can always be reduced, but information can't truly be recovered once removed.


Final Thoughts:


These are only a few of the digital audio formats currently available but they are definitely the most common. Understanding what these common file types are and what they're typically used for is definitely important for any podcaster.


If you learned something new or found an idea particularly helpful, please like and share this post.


Don't forget to subscribe to this blog to receive updates on future articles.


- Sterling Skye

 

Resources and Additional Learning Materials:


“Digital Recording.” Wikipedia, Wikimedia Foundation, https://en.wikipedia.org/wiki/Digital_recording.


Brown, Griffin. “Digital Audio Basics: Sample Rate and Bit Depth.” IZotope, 15 July 2019, www.izotope.com/en/learn/digital-audio-basics-sample-rate-and-bit-depth.html.


“MP3.” Wikipedia, Wikimedia Foundation, https://en.wikipedia.org/wiki/MP3.


“WAV.” Wikipedia, Wikimedia Foundation, https://en.wikipedia.org/wiki/WAV.


“MPEG-4 Part 14.” Wikipedia, Wikimedia Foundation, https://en.wikipedia.org/wiki/MPEG-4_Part_14#Filename_extensions.


“General Knowledge of M4A Format.” Apowersoft, 9 July 2020, www.apowersoft.com/what-is-m4a-format.


“Audio Interchange File Format.” Wikipedia, Wikimedia Foundation, https://en.wikipedia.org/wiki/Audio_Interchange_File_Format.


“What Is High-Resolution Audio (HRA) .” Technics, www.technics.com/us/high-res-audio/what-is-high-resolution-audio.