Audio File Formats

Understanding Audio File Formats: FLAC, WMA, MP3 - From RetroSound

These days, almost every device plays MP3 files. Many devices also support a wide variety of file formats. You may be wondering, "Why would I want to use any audio format other than MP3?" While MP3 has become the industry standard for audio playback, iTunes uses its own Apple proprietary format, and Windows Media uses its own in place of MP3s. You also have people who want to copy their CDs to digital files in order to archive their music collection as high-quality audio files on their home computers. Those people will undoubtedly want a higher quality file than a MP3 or Windows Media file will allow.

So how do you know which file format will sound the best? Many devices — including RetroSound RetroRadios – are capable of playing back multiple file types such as MP3, WMA and FLAC (more about these file types in a moment). Before you decide which format is going to be best for you, first you need to understand what bitrates are and the difference between lossy and lossless compression.

Bitrate

Most people who are familiar with digital audio have heard the word "bitrate," and have some kind of an idea of what that term means. In general, the higher the bitrate of your audio file, the higher the quality of the sound.

The word "bitrate" actually refers to the amount of data (in bits) that is processed in one-second. The bitrate is measured in kbps (kilobits per second). The idea here is: more audio data = higher quality audio, since there is more audio data to decode. In essence, when the bitrate is reduced using lossy compression, audio data is removed — which results in reduced sound quality. Because a higher bitrate results in more audio data, it also results in a larger file size. This is the reason it has become so common to compress audio files — so you can fit more music files on your device.

Lossy vs Lossless

With audio file formats, there are two types of audio quality: lossless and lossy. Lossless formats retain all of the original audio data. Typically, these are large, uncompressed files with lots of information and very high bitrates. There are also some compressed audio formats that retain lossless audio quality (more on that in a moment).

Lossy formats are compressed files that lose audio quality as the bitrate and file size is reduced. The files are made smaller by removing audio data that exists beyond a certain frequency range (such as hums and feedback) and by reducing the quality of certain sounds (such as cymbals and high-hats). The higher the bitrate, the more of the original data that is retained. This means that with a higher bitrate, you'll have higher audio quality but a larger file size.

To make this easier to understand, we've made a couple of very basic diagrams to help you visualize the difference between lossy and lossless compression. Referring to the diagrams below, think of an audio file as a stack of different colored blocks. The different colors in the diagram below represent different audio frequency ranges.

Lossy Compression

Referencing the diagram below, you'll see that lossy compression removes the less audible frequency ranges (represented by yellow and green blocks) to make the overall file smaller. The audio data that is read back in by your music player no longer processes the deleted data. This results in a smaller file size at the cost of audio quality.

The main benefit of lossy compression is file size. Audio CDs use a lossless format for very accurate sound reproduction. A typical audio CD containing 9 songs might use up 500 megabytes of disk space. But those same 9 songs might only use up 50 megabytes once compressed.

Lossless Compression

With lossless compression, instead of deleting extra blocks, the redundant blocks are removed and replaced with instructions. For example: In the chart below, you'll see that once our audio file is compressed into a lossless format, two blocks are now represented by one block with the number two. Three blocks are represented by one block with the number three, and so on. When your music player reads the compressed file, it processes the instructions and rebuilds the original file with no loss of the original audio data. It gives you a much smaller file size while retaining the highest possible audio quality.

The benefit of lossless compression is this retention of audio quality and a reduced file size. The downside is that the file sizes are still larger than with lossy compression, and not all music players support lossless file formats. FLAC (Lossless) FLAC is an acronym for Free Lossless Audio Codec and is a lossless audio format that allows reduced file size with no cost to audio quality. FLAC files are compressed in a way that does not reduce the audio quality, making it one of the best formats available for archiving your music. This compression makes it possible to reduce the file size by up to 60% while retaining all of the raw audio data.

FLAC was introduced in 2001 as an open-source file type and has grown to one of the most popular audio file formats today. Because it is one of the most popular lossless formats, most modern devices support FLAC playback. Unlike WAV format (the most popular lossless format), FLAC files also retain information tags — storing artist and album information.