[Music] File format types Part 2
Lossy compression format
This compression format is probably the one you use the most.
MP3
CAA
WMA
Vorbis
This is the file format.
“The human audible range is 20Hz ~ 20000Hz”
This file format has the advantage that the file size can be suppressed while maintaining a certain level of sound quality by compressing and truncating the high-frequency part that humans cannot hear.
However, the downside is that the sound quality is lower than the original data.
Among them, “MP3” is the most popular file format, and as a successor, “AAC” is often used, which was created to achieve higher sound quality. Furthermore, “WMA” and “Vorbis” are also in this format.
MP3 (MPEG-1 Audio Layer 3)
It is one of the audio formats used in the “MPEG-1” video compression standard.
It is a popular format and many popular digital audio players support it. If you compress it into this format, you can play it on many players other than iPod.
It is generally said that if you specify a bit rate of 192 kbps or higher for MP3, it will be almost indistinguishable from the original music.
Recently, the capacity of the player has increased, so I think it is good to capture at 320 kbps, which is the highest sound quality of MP3.
There is also a method called VBR (variable bit rate), which efficiently obtains optimal data while changing the bit rate in a song, as opposed to CBR (constant bit rate).
However, when using VBR, the bit rate may be partially higher than necessary depending on the song, and some players may experience problems such as interrupted sound due to insufficient performance.
AAC (advanced audio coding)
It is one of the audio formats used in the “MPEG-2” and “MPEG-4” video compression standards.
ITunes has selected this AAC format as the standard compression format as a highly efficient and superior alternative to MP3.
However, there have been times when compatibility between products was poor in the past, and in rare cases, AAC files created by third-party software may not be playable on iPod. When using the AAC format, the bit rate should be 128 kbps or higher, especially 256 kbps or higher if you want high sound quality. The songs that are managed in the iTunes store are also in AAC format and have the extension “.m4a”.
WMA (Windows Media Audio)
A music compression format developed by Microsoft for the Windows operating system.
It is used in many Windows music distribution software and digital audio players. It is said that the file size can be reduced to half that of MP3 if the sound quality is the same. WMA format files are converted to AAC / MP3 format when imported into iTunes.
However, it is not possible to convert downloaded and purchased songs with copyright protection (DRM) to AAC format / MP3 format.
