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Audio Codecs: What They Are and Why They Matter

Ever wonder what those fancy file names next to your favorite songs mean? They're called audio codecs.

A codec is a device or program that compresses data for transmission and decompresses the received data. In the case of audio, codecs affect your listening experience, whether you're using headphones, earbuds or one of the best Bluetooth speakers

Here are a few key terms that will help you understand the differences in audio codec types.

Lossy audio: This is a compression technique that does not decompress audio files to their original data amount. Lossy methods provide high degrees of digital compression, which results in smaller files. In these cases, some sound waves are removed, which affects the quality of sound in an audio file. Lossy compression is not recommended in professional settings where high quality is necessary.

Lossless audio: This is a compression technique that decompresses audio files back to their original data amount. Lossless methods can provide high degrees of digital compression, but there is no loss in size or sound quality. Lossless compression is ideal in professional audio settings where complete files are needed. Lossless compression music formats include FLAC, ALAC and WMA Lossless.

Uncompressed audio: This is an audio file that has no compression applied to it. The sound in uncompressed audio files remains the same as when it was recorded. Examples include PCM, AIFF and WAV formats.

Audio codec formats

FLAC, or Free Lossless Audio Codec, delivers CD-quality audio in a file size smaller than an actual CD. It''s also a nonproprietary, open-source codec that's great for software developers who want to use lossless audio. Though FLAC files are easily accessible, they can be six times larger than MP3 files, so they take longer to download. This format is not compatible with all devices and software, but it sounds great over Bluetooth and streaming.

Recommended services: Spotify Hi-Fi, Tidal, Murfie, Deezer Elite, Bluesound Vault, Qobuz, Linn Records

WAV, or Waveform Audio Format, is an uncompressed audio format that's great to use if you want to get the original recorded material without losing sound quality. WAV files are ideal for shorter sound bites because their uncompressed form means they're large files, making them difficult to stream. This is especially true in cases with limited bandwidth. The audio in these files is crisp, and the sound is good over Bluetooth.

Recommended services: HD Tracks, Bleep 

MP3, or Moving Picture Experts Group Layer-3 Audio, is one of the most popular audio codecs. MP3 files use lossy compression, which compacts audio drastically. In some cases, MP3 files can be 10 times smaller than WAV files. This compression method is versatile and works on nearly all playback devices.

MORE: Best Music Apps for Rocking Out

Although MP3s are major space savers, the bit rate at which they're recorded affects the sound quality. For example, MP3s encoded at 128kbps don't sound as great as those encoded at 320kbps, but listeners need to determine whether they prefer sound over storage. MP3s have been used for streaming in the past, but with higher-res streaming becoming more popular, they're not the only option out there.

Recommended services: Google Play, Amazon Prime Music, Amazon Autorip, TuneIn 

WMA, or Windows Media Audio, is available in lossy and lossless WMA formats, which gives listeners some choice. Generally, WMA files are smaller than their uncompressed counterparts, and similar in functionality to MP3s and FLAC files. Though WMA offers versatility, it's not compatible with all devices, especially Apple devices. It's possible to stream audio in WMA format, but i major streaming providers do not use it. Fortunately, for the average listener, this format sounds good over Bluetooth. Only critical ears would hear a difference in quality.

Recommended services: MediaPlayer10, PlayStream, foobar2000, MediaMonkey

ALAC, or Apple Lossless Audio Codec, sounds identical to original recorded audio, but it's compressed to a smaller size without discarding bits. ALAC works primarily with Apple products, which makes the format a bit limited for folks without iOS devices. It also takes a longer time to download than lossy formats do, but it sounds great over Bluetooth. It's possible to stream with ALAC, but this codec isn't commonly used because of its incompatibility with non-Apple devices.

Recommended services: iTunes, HD Tracks, Linn Records, Bowers & Wilkins Society of Sound

Ogg Vorbis
Ogg Vorbis is an open-source and patent-free audio codec that's great for streaming over the internet without compromising speed. Ogg Vorbis provides impressive sound at lower bit rates than other lossy formats. The only downside of Ogg Vorbis is that it compresses audio and discards data for smaller file sizes. However, it transfers audio quickly and sounds fine over Bluetooth. Because the average music lover doesn't use this format to compress audio, you won't find many compatible devices.

Recommended services: Spotify, Icecast, MainStream 

Lossy codecs (like MP3 and AAC) have small file sizes, making them ideal for streaming audio.

Lossy codecs (like MP3 and AAC) have small file sizes, making them ideal for streaming audio.

AAC, or Advanced Audio Coding, is another lossy codec that provides small audio files and works great for online streaming. AAC files aren't helpful if you need a near-replica of the original recording, because bits are discarded. But it sounds perfectly fine otherwise. The compressed file size is ideal for mobile devices.

Recommended services: iTunes, Apple Music, foobar2000

Originally created by Apple, Audio Interchange File Format, or AIFF, is an audio file that's completely uncompressed and can be played on both Macs and PCs. AIFF is identical to CD-quality audio, but its large files increase download time and take up significant space, making the format less than ideal for portable devices. Streaming is possible in AIFF, but it's not commonly used.

Recommended services: HD Tracks, Pro Studio Masters

DSD, or Direct Stream Digital, is an extremely high-resolution uncompressed audio format. DSD is even higher in quality than CD-quality and HD download formats such as FLAC and ALAC. Because DSD is such a high-quality audio codec, digital audio converters are often needed to play DSD files if they're not compatible with your computer. DSD is a demanding encoder, making it impractical for streaming (at this time). However, it's the best sound you can get over Bluetooth.

Recommended services: HD Tracks, NativeDSD, Acoustic Sounds

Bottom Line

Codecs can be difficult to learn because there are so many of them. But the key takeaway when you're learning about and using audio codecs is that they aren't exclusive, and various compression technologies can help you get the job done with similar results. When it comes to buying audio equipment, it's far more helpful to know which format will meet all of your audio encoding and playback needs.

Credit: Shutterstock, Apple

Cortney Moore is a multimedia journalist whose work has appeared in many places, including Tom's Guide, Fox News, The Sun, Buzzfeed, Yahoo Finance, and more. For Tom's Guide, she's written about a range of topics, from gaming to apps and phones. Currently, she works at Fox Business Network as an associate producer/writer.