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.
◆ World standard MP3, Apple standard AAC, Windows standard WMA
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.
This article is also read
Let’s easily convert the sound source with a service that converts analog records into digital sound sources.
◆ User-friendly bit rate of sound quality and capacity is 128 kbps to 160 kbps
The problem is the compression rate (= bit rate) expressed in the unit of “kbps”. Difficult theory aside, it’s okay if you think the point is “bitrate = standard for numerically expressing sound quality”.
“Reduce the amount of data by reducing the sounds that are not harmful to the human ear” In a compressed sound source, the lower the bit rate, the lower the capacity, but the higher frequencies are cut off. So if you lower the bitrate too much during encoding, you will get some moody sound quality somehow.
・ ～ 96 kbps …… Since the sound does not lengthen, it is suitable for talk-centric radio programs, etc.
・ 128 kbps …… No matter who listens to it, there is not much discomfort. Suitable for pop and rock with PC speakers and car audio
・ 160 kbps …… Sound quality that can be satisfied even with general audio. Suitable for loud jazz
・ 192 kbps …… There are few glitches even when listening with headphones. Even classical music with a wide range is fine.
・ 256kbps / 320kbps …… High sound quality close to that of a CD (1411kbps equivalent)
