On Thu, 16 Jul 2015 08:44:47 +0100, RJH wrote:

On 16/07/2015 04:22, 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/

If you haven't already viewed them, I would say they are *well* worth
the time spent in order to learn some basic truths of digital audio
processing.

In episode 2: "Digital Show & Tell" he refers to an article he'd
written
entitled, "24/192 music downloads are very silly indeed" where the
feedback he got suggested the need for this "Digital Show & Tell"
video.

I'd never read the article before but intrigued, I paused the video
so I
could *hand* type "24/192 music downloads are very silly indeed" into
the search box since there was no convenient link offered anywhere.
This took me to:

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

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.


I'm afraid that just reads like selective and biased, unevidenced and
unreferenced puff and hyperbole to me. Fine if that's the sort of thing
you like to read.

I'm not sure how you managed to come to that conclusion. :-(


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.

Well, yes, but are you suggesting that regardless of the pre-mix source?
Live, for example?

I believe I did include the phrase "and professional multi-track
recordings of live performances". Yes, it's from the bit of my reply you
quoted below. :-)

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'.

Once you've watched the videos and/or read the article, you can start
freeing up disk space with a clear conscience. :-)


I don't think you can QED just yet ;-)

The point of interest for me (which I think was the thrust of this part
of the thread?) is: what to do with live and (other) non-digital source
material.

In short, "The best possible job (of capturing the sound) that you
can.". After that, you process the resulting audio mix (32 bit floating
point/48 or 96 Kilo samples per second) to recreate a reasonable
facsimile of what an ideally placed listener would have experienced at
the live event in question (including the removal of any nasty transients
or noises that may have been introduced by the recording equipment itself
- excluding, of course, such transients as a knocked over music stand
which can add to the 'atmosphere' of *that* particular performance).

The point he was making was that once the final mix was down mixed and
normalised to fit within the dynamic range of the CD format (with shaped
dithering this is a massive 120dB, comfortably matching the widest limits
between the sensitivity and pain thresholds, marked in red, of human
hearing demonstrated by the Fletcher-Munson equal loudness curve plots)
you had every aspect of the performance you could usefully present (and
then some!) nicely encapsulated by the CD standard.

As a 'final product' of any work of music or other audio event, it more
than amply serves its purpose (unlike vinyl records or high quality reel
to reel tapes). The only caveat being that you're placing your trust in
the professionals involved in the recording and sound processing required
produce a good quality Audio CD.

The only remaining issue, pointed out by Jim, is the question of the
quality of the DACs used to effect a flawless replay of the audio so
carefully encoded into a Music CD. On a technical level at least, this is
a problem that was solved over two decades ago using oversampling
techniques to neatly sidestep both the demands for a 'brickwall' analogue
filter and to push the aliasing/digital artefact noise an octave or more
beyond the 22.05KHz region.

In the very early days, it was extremely expensive to make 16 bit DACs
that had an acceptable enough monotonicity[1] for mass consumer replay
products. The situation today is very much better in this regard.

The solution to the problem of storage and distribution of musical
performances to a level comfortably exceeding the most exacting of
requirements of Hi-Fi audio was developed over 35 years ago with the
advent of the Compact Disc (or rather the linear 16 bit stereo PCM
digital format that was at the heart of the process).

Today, we're no longer limited to optical disc media for the storage of
such data, computer disk drives and portable flash media now provide
viable alternatives by which to store, copy ad infinitum and distribute
audio files. 24 bit 96K samples per second 'Super Audio' adds nothing
usable to the basic 16 bit 44.1 Kilo samples per second CD format as far
as final play out of a 'produced' musical performance is concerned.


[1] ie. the plot of successively increasing binary values of voltage
counting in an unbroken sequence from lowest to highest would show an
unwanted discontinuity in the analogue voltage output plot as the higher
order bits changed state in response to all of the preceding LSBs.

For example, upon the LSBs reaching the value of 1 before clocking over
to all zeros to generate a carry to set the next significant bit to 1 to
indicate a few millivolts larger voltage, the error in summing up the
weighted bit values could produce a voltage a few millivolts *less* or
more than intended. The greater the number of bits used to encode/decode,
the greater the required precision of the laser trimmed resistor network
used in the DAC to accurately translate binary word values into
corresponding analogue voltage levels.

Philips realised that they could use a 4 times oversampling technique
using cheaper yet higher precision 14 bit DACs to achieve exactly the
same dynamic range performance of a conventional 16 bit DAC using a times
one sampling rate.

Not only where they able to solve the 'monotonicity' issue at a stroke,
the oversampling technique also introduced two additional benefits. The
first being that the inevitable digital hash and aliasing products were
all pushed into the 88KHz part of the spectrum, well clear of the
problematic 22KHz region that had mandated the use of 'brickwall'
analogue filtering required of the primitive methods using expensive 16
bit DACs. The second benefit being that cheaper, less ripply analogue
filtering could be employed to protect the following analogue stages (and
the listener) from both digital artefacts and unwanted aliasing products.

Eventually, within a few short years, the manufacturing costs of high
quality 16 bit DACs fell to the point whereby 2 and 4 times oversampling
could be used to 'outdo' the Philips 4 times oversampled 14bit DAC
response to crappy 'straight sampled' 16 bit DAC based products.

The remaining issue with DACs was the analogue output stage clipping
that afflicted some of the earlier products due to inadequate voltage
rail provisioning derived from the "Join the dots" peak amplitude
calculations by some rather naive designers who didn't fully understand
the process of handling a bandwidth limited analogue signal encoded into
the digital domain.

The simple solution for these naive designers was to advise them that if
they were going to persist in a "Join the dots" view of the analogue
output stage requirements then they merely had to double the 'calculated'
minimum rail voltage by a factor of two to be safe.

I suppose there must be plenty of early kit out there with such (easily
remedied at the design stage) flaws in the hands of 'many an audiophile'
who believe their venerable CD player made by famously expensive
manufacturers (Marantz et al?) must be perfection personified since
digital audio recordings cannot possibly suffer the horrors of clipping,
not even as a result of a 'cut and dried' replay process that, in
principle at least, can only be totally perfect.

Indeed there may be some, who may well have (based on auditioning tests)
chosen a CD player flawed by a clippy DAC over one with a non-clipping DAC
because 'it sounded brighter' or 'had more clarity'.

One would hope by now that the more reputable manufacturers of CD
players who subscribe to the best practices of "High Fidelity" have long
since 'put this one to bed', removing any final (misplaced) criticisms of
the, now venerable, CDDA format.


--
Johnny B Good