Ass#5: Quality of Audio File

            First, the audio file that has the highest quality is the uncompressed file. It keeps almost every details of the sound and it is nearest to real sound. The sounds in the CD also use this format. This uncompressed audio file contains every signal of sound wave even the sound that humans cannot hear. The example of this kind of file is WAV file, which is compatible with Windows, for Macintosh is AIFF. Anyway, to keep every detail of the sound, it needs a huge space. The uncompressed audio file is the biggest audio file, a file of three to four minutes can be more than 30 Mb.

            Second, the medium quality audio file is the lossless compression file. The lossless compression allows the exact original data to be reconstructed from the compressed data. This technique also used with other applications such as ZIP file and PNG image. This kind of audio file is not different so much from the uncompressed file. If we compare by hearing directly, it is so hard to distinguish between these two files. The example of the lossless file is Apple Lossless or ALAC. The Apple Lossless was introduced on April 28, 2004 as a feature of iTunes 4.5 and QuickTime 6.5.1. However, the lossless file is very difficult to implement, so it is not so popular in Windows. Nevertheless, we usually use the lossless compression technique with the text file more than the audio file or media file.

            Third is the lossy compression file. It is the lowest quality of the audio file but it is the most popular format. The lossy compression audio files discard the range of signal that humans cannot hear even the vague range of signal. In fact, this technique discards all details that humans cannot perceive. MP3 is the example of this type of audio file. It is the most popular audio format today because its size is quite small, three to four minutes song is just about 5 Mb. Anyway, even though the lossy audio file has the lowest quality and we can see or hear the differences between lossy file and uncompressed file clearly, that low quality is acceptable. Moreover, this type of file is commonly used in streaming media because its size is small; it is convenient to transfer the file.

            In addition, uncompressed, lossless compressing, and lossy compressing are the techniques that are used to handle the data, not only the audio but also all of types of the data. These three techniques give different qualities. You can choose which good quality you like when you save the file by adding the file extension after a filename.