On Tue, 17 Jan 2017 20:38:08 +0000, NY wrote:

"Tim Watts" wrote in message
...
On 17/01/17 16:25, whisky-dave wrote:

Personally - I buy CDs and rip (carefully with software that retries
errors rather than skips), then encode lossless, plus a second max
bitrate MP3 for and devices that cannot handle lossless.

Where we should be right now is being able to buy digital lossless
media at better than 44kHz sampling...

44.4kHz was a compromise between quality and play time. It was a very
good compromise, but we might as well go a little better now there's no
reason not to.

I think that 44.1 was chosen to be sufficiently good that only dogs and
bats would notice the limitations.

It is generally accepted that human hearing is 20-20,000 Hz
(https://en.wikipedia.org/wiki/Hearing_range and many other sources) and
diminishes with age.

Nyquist's sampling rate says that to represent an analogue sine wave of
frequency f, you need a sampling rate of at least 2f.

So for 20 kHz, you need to sample at 40 k samples/sec. Allowing for
low-pass anti-aliasing filters that are not perfect, 44.1 or 48 k
samples/sec are sufficient. The exact values of 44.1 and 48 are for
compatibility with other systems (I forget the details, but I think they
are related to using PAL and NTSC video recorders with a few samples per
picture line for mastering early digital recordings).

So what would be the advantage of increasing the sampling rate? What
would the benefit be of being able to reproduce audio frequencies beyond
about 20 kHz?

Maybe there is a need to increase the sampling depth to greater than 16
bits (ie -32K to +32K), though I think subjective tests have shown that
there is no perceived advantage, as the signal to noise ratio is already
so great that it exceeds that of analogue amplifiers that would
reproduce the sound.

For presentational purposes, the CDDA standard exceeds requirements for
Hi-Fi reproduction of published musical performances by a more than ample
margin as anyone who has read "Monty" Montgomery's very fine article on
"24/192 Music Downloads ...and why they make no sense" linked to he

https://people.xiph.org/~xiphmont/demo/neil-young.html

could have told you.

For the more sceptical of us that are, however, interested enough to
learn more about 'digital audio', there is a very nice "Digital Show &
Tell" video on this page: https://xiph.org/video/vid2.shtml which
demonstrates the whole analogue to digital to analogue processes in a
straight forward no-nonsense and entertaining manner[1] which, at the
very least, should leave the most sceptical of us questioning any of
their preconceived notions that the "More is Better" claim for SACD has
any validity in fact (Hint: for the purposes of final reproduction, it
has absolutely none).

[1] For anyone with the slightest interest in digital audio, this video
is well worth the 23 minutes and 52 seconds of the time required to watch
it right through to its conclusion.

--
Johnny B Good