On Sep 1, 2010, at 3:19 PM, n2gyn wrote:
It's NOT a microphone issue. It's the small bit processing. I have
been in Pro sound for most of my life. Their is NO WAY to get any
quality at 8bit. This is unexceptionable to me! I rather listen to
all the QRM and QRN in the world with analog.
I am very surprise that their are not more people that feel this way.
The bit rate has to be at lest 28bit to starting sounding acceptable.
John
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It isn't a microphone issue (nor is it an 8 bit A/D issue) --
AMBE is not a simple A/D waveform sampler, it examines the complex
signal and encodes "hints" via a "codebook" to reproduce the waveform,
that is how it gets its amazing compression. This is not an apples to
apples comparison. The sample rate and number of bits per sample are
important to providing a good input signal but the chip really is
looking for 8 Khz (16-bit linear, ųlaw, or alaw -- optionally 32Khz
using AD 73311 -- see http://www.dvsinc.com/manuals/
AMBE-2020_manual.pdf Page 39) and puts out the same, but in between it
doesn't resemble anything close to a bit sampler.
Anything one knows about sample rates and size (in bits) is largely
irrelevant as the limiting factor is the AMBE algorithm and its lookup
codebook.
http://en.wikipedia.org/wiki/Advanced_Multi-Band_Excitation
John D. Hays
Amateur Radio Station K7VE
PO Box 1223
Edmonds, WA 98020-1223 VOIP/SIP: [email protected]
