Lab Report – Audio Data Compression
Introduction
When a producer/artist releases a new piece of music it is essential that the audio be of the highest possible quality and would therefore be exported as either a WAV or AIFF uncompressed file format. However, whilst these files may maintain the highest quality audio they are not very practical when it comes to sharing over the Internet for use with personal music players or online digital streaming, which asks the question, “How can the size of these files be reduced for a more practical use, whilst maintaining quality?”
The two main types of data are ‘Lossy’, and ‘Lossless’ audio files and if a high quality piece of compressed audio was desired, compression which shrinks the file size but doesn’t lose any of the original audio’s information would be used, such as FLAC or ALAC data.
Method
In order to develop a greater understanding of audio data compression an experiment was carried out to inspect what happens to a piece of audio when compressed into different file formats. FLAC, MP3, MP4, and OGG file formats, each of a low, medium, and high quality, were analysed to find out what happens to the audio’s stereo image, the ambience within the tracks, the balance between each of the instruments, and how any of these may change in sound. To ensure accuracy within the results only one genre of music was used for all the different file formats, and this was a heavily distorted guitar line over a backing track. A note was then taken of each audio files spectral frequency display to back up the results of each analysis.