What is the best way to properly use compressed sound sources such as MP3, AAC and WMA?
When you listen to music on a smartphone or iPod, what you seem to know but don’t understand are digital compressed sound sources like MP3, AAC, and WMA. Let’s think again about “what format” and “what bitrate is good”.
◆ World standard MP3, Apple standard AAC, Windows standard WMA
You all know that there are various formats of “digital sound sources”.
The most familiar is the WAV format, which is also used for CDs. Being an uncompressed format, there is no deterioration in sound quality and it is very versatile, but the capacity is not small, just over 50 MB in 5 minutes.
Therefore, when used with a portable music player such as a smartphone, iPod, or Walkman, it is common to convert (= encode) 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 the main ones.
・ MP3 …… The oldest compression format established in 1995. There are many compatible products, and it is the de facto standard that can be used in any case. “MP4” is a video standard, so don’t confuse it.
・ AAC (M4A / M4P) …… A standard established after MP3, which is a standard format for Apple products such as iPod and iPhone. M4P is a copyright protected file. 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 with Windows and many products are also used in voice recorders.
Based on these characteristics, let us consider the compression format depending on the device used.
