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Jay - atldigi
 
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Default 16 bit vs 24 bit, 44.1khz vs 48 khz <-- please explain

In article , "Ric Oliva"
wrote:

Ok, so I understand that 44.1k is 44,100 samples per second and 48k is
48,000 samples per second. Obviously 48,000 is better. I'm not exactly
sure what bit rate is though? CDs are 16 bit, DVDs are 24. What exactly
does that mean though?


http://www.promastering.com/pages/techtalk.html

Article 1 and 2 deal with bit depth and dither, article 3 with sampling
rates. Recording at wordlegths higher than 16 bit is helpful. In
practice, 20 is almost always as good as 24 for recording since A to D
converters don't have the dynamic range to capture 24 bits and the lower
bits just contain the self noise of the box. For digital processing,
however, you want to use longer wordlengths like 48 bit, or at the very
least, 32 bit floating point.

Most simply stated, wordlength (or bit depth) is dynamic range. Bit rate
actually means something a little different, but we won't get into that
right now as you obviously are asking about bit depth. For every bit you
get about 6 dB (just over actually) of dynamic range. 16 bit CD has 96dB
while 24 bit has 144. Extra bits do not add headroom; they add footroom.
0 dB FS (full scale) represents the same value in both 16 bit and 24 bit
audio. The extra bits come into play at the bottom of the range. You are
able to record smaller events - sounds at a lower level.

In addition to dynamic range, it also means noise. in 16 bit, there is a
noise floor of -96dB while 24 bit has a noise floor of -144 dB. 24 bit
offers no additional accuracy in the top 96db of the dynamic range.
Actually, an 8 bit recording is just as accurate as a 24 bit recording
from 0dBFS to -48 dB. The -48 dB noise floor is quite obtrusive and the
8 bit recording certainly sounds worse, but those top 48 dB are just as
accurate as a 24 bit recording. If you took a 24 bit file and added 96
dB of noise, it would sound like an 8 bit file.

Invariably any discussion of bit depths must eventually include dither.
This, however, I'll leave to the tech talk articles I've pointed you to,
or to a google search for the many posts that have appeared here in
r.a.p. Be aware, however, that there are some common mistakes made
quite often when discussing these subjects, so avoid the myths.
Sometimes common sense tends to fail you until you understand how
digital audio truly works, so some things that seem to make intuitive
sense at first are actually technical rubbish.

--
Jay Frigoletto
Mastersuite
Los Angeles
promastering.com