folder

Folders have time stamps that are the present date and time when they are copied and pasted, but they have ones that they were created when they are cut and pasted. So it is good to cut and paste folders if we want to keep their time stamps.

The Quality of Sound in CDs

Recently I prefer to use lossless codecs instead of mp3. In many cases, bitrates affect the quality of sound: the higher bitrates the better quality. I wondered how many bitrates CDs have, so I searched and found it.

16 bits · 2 channels · 44100 Hz = 1411.2 kbps

"16 bits" means the quantity of data in one sample. "2 channels" means stereo: right and left sounds. "44100 Hz", or sometimes "44.1 kHz", means the times of calculations in one second: CD players calculate samples 44,100 times in a second.

How much data does music need? Many albums contain over 60 minutes. Let's think about a just 60 minute CD.

1411.2 kbps · 3600 seconds · 1/8 = 635,040,000 bytes ~ 635 MB

"1/8" means conversion units from bits to bytes.

CD-R/RW have usually 650 MB, but some have 700 MB. We can recond music about 60 minutes in 650MB CDs and 70 minutes in 700MB CDs.

650 MB · 8 bits / 1411.2 kbps ~ 3685 seconds = 61 min. 25 sec.
700 MB · 8 bits / 1411.2 kbps ~ 3968 seconds = 70 min. 8 sec.

But unfortunately we can't use maximum spaces. Some spaces are necessary in addition to spaces for recording music when we write onto discs. This happens with DVDs and Blu-ray Discs, too. We can know this when we format blank discs. Perhaps makers will say, "It's because of the standards."

I like the spelling of "disc" better than that of "disk".