What is the best way to use compressed sound sources like MP3, AAC and WMA correctly?
When listening to music on a smartphone or iPod, what you seem to know but not understand is digitally compressed sound sources like MP3, AAC, and WMA. Let’s think again about “in what format” and “how much bit rate” is good.
You all know that there are various formats of “digital sound sources”.
The best known is the WAV format, which is also used for CDs. Since it is an uncompressed format, there is no deterioration in sound quality and it is very versatile, but the capacity is not small, just over 50MB in 5 minutes.
Therefore, when used with a portable music player such as a smartphone, iPod, or Walkman, it is common to convert (= encode) from WAV to compressed sound sources such as MP3, AAC (M4A / M4P), and WMA.
By the way, compressed sound sources are used from the beginning for download distribution like iTunes. AAC for iTunes, MP3 for Amazon, and WMA for major national distribution sites are mainstream.
・ MP3 …… The oldest compression format established in 1995. There are many supported products, and it is the de facto standard that can be used in any case. “MP4” is a video standard, so don’t get it confused.
・ AAC (M4A / M4P) …… A standard established after MP3, which is a standard format for Apple products such as iPod and iPhone. M4P is a file protected by copyright. AAC is also used for audio on digital terrestrial broadcasts and digital BS on television.
・ WMA …… A format advocated by Microsoft. It has a strong affinity for Windows and many products are also used in voice recorders.
Based on these characteristics, let’s consider the compression format depending on the device used.
