In article , Johnny B Good
wrote:
On Wed, 15 Jul 2015 20:56:38 +0200, John R Leddy wrote:

'Jim Lesurf[_2_ Wrote:
;94195']FWIW I've never felt that going as far as 192k/24 made much
sense for home replay. 96k/24 seems a convenient 'compromise' to me
given the use of decent replay equipment. But YMMV.

It is perhaps worth pointing out to people that if you covert to flac
you will usually find that the resulting 96k/24 file is *not* twice
as big as a 48k/24 flac from the same source.

In general there isn't a lot in the ultrasonic region, and the flac
compression can take advantage of this.

The main difference tends to be that there are more bits devoted to
'noise' in 24bit than 16bit. And flac will faithfully keep those
details.
I can't bring myself to allocate over a gigabyte of storage space to a
single-CD album. 24-bit 96kHz albums seem to average just under a
gigabyte which suits me fine. This aspect, and the fact I was willing
to convert my 24-bit 192kHz files to 24-bit 96kHz, allowed me to
change my first 24-bit 192kHz network audio player for one which has a
maximum 24-bit 96kHz playback. Truth be told, until participating in
this thread, I would've quite happily converted my files to 16-bit
48kHz if I had to and not thought any more about it.

I'd much rather a good quality production and master of a 24-bit 96kHz
album, than a 24-bit 192kHz album of poor quality. Shame someone
decided it was easier to sell numbers than improved quality. I
would've preferred the better quality no matter what numbers were
associated with the file. Maybe that's a giveaway when thinking about
the relevant skills within the industry. To fall back on the public's
lack of knowledge seems a bit defeatist and insecure to me. That said,
I guess we do tend to believe anything we're told and spend our money
accordingly.

Fortunately, I have such appalling taste in music none of this
probably matters a great deal anyway.

I've been following this discussion with a growing dismay as phrases
such as "96k/24 seems a convenient 'compromise' to me" started to rear
their ugly heads.

A guy by the name of Monty Montgomery presented a couple of very
interesting videos that nicely relate to the whole business of digital
audio (and video). The links to those videos can be found on this page:

http://xiph.org/video/

Yes, I've seen them in the past and would recommend them with one caveat.
cf below.



I read about halfway through to the key facts - I'll read the rest
later on- where he states unequivocally that 16 bit 44.1 CD audio far
exceeds the capabilities of even the most superhuman of hearing
abilities. IOW, once you're dealing with a finalised music performance
properly committed to CD, that's it as far as 'perfection' is concerned.

The problem is that he does omit various factors that make reality
different from 'perfection'. This includes the DAC used as that's the
'final' version produced by the digital chain.

The key point to keep in mind for real engineers is that as a general rule
*every* process or conversion in a chain can be expected to degrade or
alter the information.


The only way that a 24/96 "Hi Definition" version is going to sound any
better is if the final mixdown processing used to create the CD had
been comprehensively buggered up.

Afraid that isn't an absolute truth. The reality is more complex. Even a
technically perfect downconversion for the CD exposes the listener more to
any imperfections in their DAC. And alas, no practical engineered system
will be perfect.

The point is that each stage will tend to alter the results. A perfect
Audio CD is only a beermat or car scarer if you ignore the stage of being
able to play it. :-) So the aim if you're concerned with quality is to
keep the problems well clear of the audible result *at every stage along
the way*. i.e. inc your DAC, etc.

Sadly, for most popular music and
'digital re-masterings' of analogue studio recordings and professional
multi-track recordings of live performances, the 'buggering up' is the
result of deliberate vandalism, often in the name of 'winning the
loudness wars'.

Certainly true. And one of the problems with downconversion is that it
tends to generate *higher* peak values in between the sampled instances. So
the simple act of downconversion can lead to a clipped result if the source
material was 'as loud as possible' without itself being clipped. Again,
what you get out here may depend on your DAC.

There is also a more basic problem people don't seem fully aware about. But
which does cause them to engage in activities like 'which reconstruction
filter do I like?'. 8-]

The optimum choice of reconstruction filter (and resampling filters)
depends on the filtering used in the ADC when the digital samples were made
from the incoming audio during recording. The meaning (information payload)
of the sampled data values is determined by the ADC filtering. This is a
fundamental Information Theory point about which many engineers, etc, seem
totally unaware. To reconstruct an analogue shape you need to know what
input filer was used. Otherwise the result will be altered in ways you
can't predict.

Given that you usually have no idea what filter was used, and it changes
from one recording to another, this is a poser for making a 'perfect' DAC.
But, again, you can help shove away from audibility such issues by keeping
with high rates until you get to the final DAC.

Jim

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