What are audio files?

Audio files are sound files or files that play a sound when clicked. One of the most common audio formats is the wave file or [nome do arquivo aqui] .wav. Another is the MP3 file or [nome do arquivo aqui] .mp3 . The type of audio format used is indicated by the file extension – the last three letters after the period. Standard audio players included with operating systems play common types of audio files, but more exotic sound formats may require codecs to be downloaded for the player to extend its capabilities.

An MP3 player with audio files.

The ubiquitous waveform was developed by Microsoft® and IBM&reg, with Apple® offering a compatible standard known as the Audio Interchange File Format (AIFF). Both types of files will play on both IBM and Macintosh computers. WAV and AIFF are two types of lossless audio formats, or audio files that store the original audio bitstream source without any quality loss. These formats were originally used for operating system sounds such as beeps, bells, and spoken messages. As people began to customize their systems, short sound clips from movies and television or snippets of favorite music became widely available online as wave files.

A potential disadvantage of the lossless format is its large footprint due to its high quality. When people started ripping music CDs to computer, they quickly learned that ripping to WAV can consume up to 5MB per minute. A four minute song can result in a 20 MB wave file. Online multimedia content presented another problem, as a lossless audio stream was too bulky to download easily, especially on the standard connection at the time, which at the time was dial-up. The development of compressed files or lossy formats like MP3 has answered the call.

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A compressed sound file sacrifices some quality loss (hence the term “lossy”) in exchange for a smaller footprint or file size. MP3 audio files are a perfect example. A 20 MB wave file can be converted to MP3 format, resulting in a file of only a few megabytes. Other lossy formats include Ogg Vorbis (.ogg), Advanced Audio Coding (.acc) or MP4 (.mp4), and Windows® Media Audio (.wma). ACC/MP4 files are slightly smaller in size than MP3s, with an encoding scheme that supposedly results in superior sound quality to MP3s. However, many sources claim that OGG generates the best lossy audio files, smaller than MP4s with equal or better sound quality.

Going from a waveform to a lossy format, the quality loss should be minimal, although audiophiles will be able to discern the difference. For this reason, many music lovers choose to archive music in lossless formats such as WAV or AIFF and generate lossy files from the originals as needed. Lossy files can be used with portable players where storage is limited and quality is not that critical. Untrained ears will likely not hear the difference between an original wave file and its lossy reduced counterpart, but keep these lossless originals for burning CDs or playing in the home entertainment center.

Other types of audio files are embedded in “container” formats used for movie files that include sound. Apple’s QuickTime®, RealMedia® by RealNetwork and Audio Video Interleave® (AVI) by Microsoft are some examples.

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