Sample Rate (2)

The Music Telegraph | Text 2018/12/19 [10:32]

Sample Rate (2)

The Music Telegraph| 입력 : 2018/12/19 [10:32]

Sample Rate (2)

Every cycle has 'Two' energy changes:

so, @ 20 Hz, sample rate (S.R.) is 40 Hz

CD's (Compact Disk) Sample Rate = 44.1 kHz —-> CD's Frequency = 22.05 kHz

44.10 / 22.05 = 2 Samples / Cycle

S.R. = Number of samples / sec

Freq. = Number of cycles / sec

ex) If a CD's frequency is 18 kHz then:

44,000 / 18,000 = 2.45 samples / cycle

If a CD's frequency is 10 kHz then:

44,000 / 10,000 = 4.44 samples / cycle

[side trip]

A (Analog) = Recording

D (Digital) = Mixing

D (Digital) = Mastering

20 Hz ~ 20 kHz:

- Audible frequency (to human)

*Older people lose high frequency hearing

Bits = Amplitude

S.R. = Frequency

- So, number of bits   then  Amplitude (volume)

- Sample Rate   then  Pitch

e.g.

4 bit

8 bit - Standard

16 bit - CD

24 bit - DVD / SACD

Therefore,

4 bit = 0 ~ 15 = 16 values

8 bit = 0 ~ 255 = 256 values

16 bit = 0 ~ 65k = 65k + 1 values

24 bit = 0 ~ 16777216 = 16777217 values

Every 1 bit = 6 dB (decibel):

If you increase the level of a signal by 6 dB, it will sound twice as loud

- At 16 bits, maximum volume is 96 dB (16 x 6 = 96)

- At 24 bits, maximum volume is 144 dB (24 x 6 = 144)

[side trip]

DVD-A (96kHz - 24 bits):

96,000 x 24 = 2,304,000 bits/sec ÷ 8 = 288,000 bytes/sec ÷ 1,000 = 288 Kbytes/sec ÷ 1,000 = 0.208 Mbytes/sec ==> x 60 = 17.28 MB/min

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