Digital Music Formats an Introduction

In this article I will be discussing the differences between the various type of audio files. By the end of this article you will have a basic understanding of the various audio formats.

Uncompressed audio formats

The Uncompressed audio formats contain all data that was originally captured from the data source such as the CD or the original sound sample. Uncompressed audio files include the following formats

  • WAV (Waveform Audio File Format)
  • AIFF (Audio Interchangable File Format)

Lossless Compression

Lossless compression is when no data is lost as part of the compression process. Typically require half the storage space of an uncompressed WAV file. Lossless Compression file formats include

  • FLAC (Free Lossless Audio Codec)
  • ALAC (Apple Lossless Audio Codec)

Lossy Compression

Lossy compression offers even better compression rates than Lossless. However, this comes with a cost as some of the data is lost. Potentially resulting in a reduction in sound quality.  Even though techniques are used to remove parts of the sound that have the least impact on perceived audio quality.  Lossy Compression file formats include.

  • MP3 (MPEG Layer 3 Audio Quality)
  • WMA (Windows Media Audio Format
  • OGG (Ogg Vorbis)

Lossy Compression V Lossless Compression

During the 1990’s it became popular to rip CD’s and store the ripped music on your computer which became a media library. For your music collection, you didn’t have to hunt around for the CD you could just scroll down the track you wanted to listen to or use shuffle play. For most of us, a lossless file format such as MP3 or WMA was the only way to go as hard drives were still relatively small.

At around about the same time, MP3 players became popular and again the storage capacity wasn’t massive. You needed small files if you were to get your entire music collection onto an MP3 player.

In the last decade or so most of us listen to music via music streaming services and until recently these music streams used Lossy compression. However, as the Internet bandwidth has increased the number of music streaming services offering lossless music streaming formats have been increasing. Computer storage has also become cheaper making it practical to store lossless files on your computer or media server as well.

Sample Rates

Besides compression, another factor to consider with music is the sample rate.  CD-quality is 44Khz which means 44,000 a different snapshot of the soundwave was taken at every second which are then converted into a string of binary digits.

44Khz sample rate allows the capture of sound upto 20Khz which is the maximum frequency the human earing can hear.

Sample Depth

The sample depth is the amount of data captured. More depth allows the storing of more information the soundwave to be stored. An Audio CD has a 16-bit audio depth. Each sample captured has a word length of 16 binary digits to store the sound wave data allowing 65,535 distinct values to be stored.

Conclusion

Lossy files are suitable if you have limited storage space or are streaming music over a network with little bandwidth, but for better sound quality use Lossless compression.

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