On Mon, 20 Aug 2007 18:24:34 -0400, Jerry Avins wrote:
Don Pearce wrote:
On Mon, 20 Aug 2007 14:13:04 -0400, Jerry Avins wrote:
Don Pearce wrote:
On Mon, 20 Aug 2007 10:58:53 -0800, glen herrmannsfeldt
wrote:
Don Pearce wrote:
(snip)
Quantization isn't important. If you don't quantize all it means is
that you are dealing with floating point rather than integer numbers.
Still digital of course. I can't think of any floating point ADC's off
hand, of course.
Floating point is still quantized, though not the same as fixed
point (integer) data.
Effectively it isn't. Of course if you apply this strictly, it is, but
a floating point number can be so detailed that it would be
essentially impossible to find the quantization steps in the real
world.
Instead of floating point, Mu-law and A-law coding are commonly
used for digitized audio:
http://en.wikipedia.org/wiki/Mu_law
http://en.wikipedia.org/wiki/A-law_algorithm
The result is similar to the use of floating point, but the
coding is different.
Nonsense. Mu and A law are simply a way of rescuing some decent
distortion performance from a limited number of bits by making the
quantization steps smaller as the signal gets smaller. The result is
lower noise with the penalty of slightly higher distortion. There is
no similarity whatever to floating point.
There's a gap in your understanding. the "segment" is the equivalent of
floating point's exponent, and the bits that divide the segment into
equal parts are like floating point's mantissa.
Jerry
No gap. The expressions are used simply to derive a set of
quantization points which, in the telephony systems that use them,
generate 8 bits of data - no floating points, which would many more
bits to encompass a mantissa and an exponent. The result is just the
integer numbers -128 to 127.
Oh? The concept of floating point prescribes a certain number of bits?
That you fail to see the parallel doesn't mean there isn't one.
No idea what that meant. Mu and A law are used in telephony. The
system uses 8 bits. Mu and A law are necessary because there ARE only
8 integer bits. If telephony could afford, say, 16 bits, there would
be no need for Mu and A law. The bits are integer. There is no
floating point. Why is that so hard to grasp?
d
--
Pearce Consulting
http://www.pearce.uk.com