Jim,
Even though a DAC or player may use an LED or display to indicate the file format entering the component, isn't it possible the DSP could be upsampling anyway?

Would I be right in thinking we are all continuously bombarded with frequencies above and below our hearing capabilities, and as such this condition would simply envelope ultrasonic frequencies deliberately introduced to an audio replay system, to the degree we wouldn't experience a difference if those ultrasonic frequencies were absent either? What with memory, my brain manipulating my own high and low pass filters as I concentrate, and the varying noise floor within my listening environment, is it realistic for me to be concerning myself with something imperceptible? I may have just answered my own question. However, whilst I'm not inclined to investigate this further via the web, I would respect your opinion.

Handy in the studio for minimising additional noise when utilising multiple effects, but once packaged for replay haven't the benefits already been achieved?

Agreed. However, during a time when bitdepths and sampling rates are sold more like commodities rather than formats, shouldn't we point out the same file reduced within reason, to say 16-bit 48kHz, would replay with absolutely no perceptible loss of quality experienced by the listener?
John.

More audio tomfoolery
 

In article , John R Leddy
wrote:

'Jim Lesurf[_2_ Wrote:
;94178']The problem is that real DACs aren't perfect. So when
replaying 44.1k a DAC may generate effects which extend well below
22.05kHz.Jim,
Even though a DAC or player may use an LED or display to indicate the
file format entering the component, isn't it possible the DSP could be
upsampling anyway?

Yes, quite likely in fact. But if the original was downsampled to 44.1k
that downsampling would introduce 'flaws' to some extent, and so would
upsampling again in the DAC. These 'flaws' may be inaudible (particular if
you don't have the original to compare with). But may not.

From the POV of preserving quality and minimising the addition of
flaws/losses that may become audible the ideal is to avoid all conversions
that can be avoided.

Given that it is now easy to record and playback 96k/24 this means it is
now easy to simply avoid and forget such 'risks' as downsampling and
upsampling along the way.


'Jim Lesurf[_2_ Wrote:
;94178']Simple plots of what single-frequency tones someone can hear
don't tell you about what happens when they hear more complicated time
varying signals with many components. Look on the web for the work of
Oohashi for example. Human hearing is non-linear. Real DACs, etc, are
non-linear too. The presence/absence of 'Ultrasonic' components can
affect what we perceive. Depends on the circumstances, etc.
Would I be right in thinking we are all continuously bombarded with
frequencies above and below our hearing capabilities

Yes. However the point to bear in mind is that for, say, acoustic
instruments, the 'ultrasonic' output is coherently related to the 'audible'
output in a way characteristic of that instrument. This isn't the case for
random background noises like someone dropping a bunch of keys some way
away from you. Human hearing, being *physically* non-linear can therefore
produce different results for the cases.

How much this *matters* is another question. But there is reasonably well
obtained (in academic terms) evidence that it has an effect on human
perception.

, and as such this
condition would simply envelope ultrasonic frequencies deliberately
introduced to an audio replay system, to the degree we wouldn't
experience a difference if those ultrasonic frequencies were absent
either?

No, the results may be different for the above reason.

In general terms a linear swept tone burst has the same spectrum as an
impulse function with the same energy-time spectrum. They sound very
different, though. Timing and coherence do matter.


What with memory, my brain manipulating my own high and low pass
filters as I concentrate, and the varying noise floor within my
listening environment, is it realistic for me to be concerning myself
with something imperceptible? I may have just answered my own question.

As you realise, by self reference if you find it is 'imperceptable' then it
won't matter. But it is quie possible that in some cases it *is*
perceptable.

However, whilst I'm not inclined to investigate this further via the
web, I would respect your opinion.

'Jim Lesurf[_2_ Wrote:
;94178']So the advantage of playing 96k material on a good system is
that it tends to shove these problems further away from the regions
where they can have an effect on what we hear.
Handy in the studio for minimising additional noise when utilising
multiple effects, but once packaged for replay haven't the benefits
already been achieved?

Not if you then downsample for final delivery to the playing system. That
then can introduce flaws/changes

'Jim Lesurf[_2_ Wrote:
;94178']And in practice, once you're recorded and processed using
96k/24 there doesn't seem much point in downgrading the result in the
age of cheap multi-TB drives.
Agreed. However, during a time when bitdepths and sampling rates are
sold more like commodities rather than formats, shouldn't we point out
the same file reduced within reason, to say 16-bit 48kHz, would replay
with absolutely no perceptible loss of quality experienced by the
listener?

If I were certain that were true in all cases for all listeners in all
situations, yes. But we do have evidence that there are objectively
testable reasons based on human physiology that such effects may be audible
at times for some people, etc. So I can't rule out that it matters.

FWIW When I listen to a well-made CD, or indeed LP, or the BBC iplayer, I
can often happily enjoy the music without being aware of such possible
problems. So I don't advise losing sleep over this. :-)

The snag is that all too many CDs/LPs are *not* well made. So again,
bypassing as many avoidable 'reprocessings' may be advisable as a general
strategy.

But of course, many 'high rez' files prove to have flaws. e.g. have a look
at http://www.audiomisc.co.uk/HFN/HealthCheck/Flac.html

In particular compare the sample probability plots for the 'My Sweet Lord'
(96k/24bit flac) commercial download with the decca one of Britten's War
Requiem. The Britten sounds superb - amazingly so when you realise how long
ago it was recorded. The Harrison is perhaps less impressive in technical
terms, despite being much more recent.

So the bottom line is always that those making and processing recordings do
need to take care as well as use good kit. But once they do, one basic
sensible principle is to simply avoid any needless process because entails
a risk of some 'harm' to the final result. That doesn't guarantee a superb
result, but it does dodge some possible landmines, so makes a better result
more likely.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
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More audio tomfoolery
 

On Tue, 14 Jul 2015 04:21:05 +0200, John R Leddy
wrote:


Vir Campestris;94176 Wrote:
...I'm not convinced why you need to playback at 96kHz. I suspect these
days my hearing ends at well under 15kHz - but surely yours doesn't hear
over 40kHz?
You're right, we don't need a 96kHz sampling rate for audio replay.
However, a high sampling rate isn't utilised to extend audible high
frequencies.

I know of a very useful web site that has visual graphs of sampling
rate converter quality. It uses a spectrogram to show the generation
of alias products, comparison of various frequency and impulse
responses, and enables comparison of quite a few different pieces of
software.

http://src.infinitewave.ca/

d

Thank you for the link Don.
I've already converted the few 24-bit 192kHz albums I had to 24-bit 96kHz using Audacity 2.0.5.
I'm guessing, when converting from 192kHz to 96kHz, the same issues could be encountered as illustrated in the Help link SRC Comparisons - Help and Information where conversion was 96kHz to 44.1kHz.
Whilst it's too late for my 24-bit 192kHz albums, I now see where Jim's coming from when he suggests not to convert files, so thanks for that.
No doubt the article will lead me off on another web adventure in the near future, as I highlight text, right-click, and search DuckDuckGo.
Thanks,
John.

We're not going to get around the DAC or player oversampling-upsampling-oversampling so I take it I shouldn't get too bogged down with all this. Let's face it, compared to my LPs and cassettes of the past I'm doing pretty well as far as sound quality goes.

I'm happy to adopt this strategy.

So we really do want the bitdepth and sampling rate as used in the studio. I was hoping to avoid 24-bit 192kHz files.

More audio tomfoolery
 

In article , John R Leddy
wrote:


'Jim Lesurf[_2_ Wrote:
;94188']Given that it is now easy to record and playback 96k/24 this
means it is now easy to simply avoid and forget such 'risks' as
downsampling and upsampling along the way.So we really do want the bitdepth and sampling rate as used in the
studio. I was hoping to avoid 24-bit 192kHz files.

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.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Jim,
Thanks for taking the time to reply to my post.
I read your CD and FLAC Health Check webpages - makes me think there's little hope for decent quality recordings being commonplace. I can't bring myself to replace all the music in my current collection. Never minding the time and effort which would be required, I simply couldn't afford it financially. From what I've read on the web, recent remasters don't guarantee much anyway. At times I find myself wondering why I got into high fidelity at all, when the media is sometimes so blatantly naff. However, at some point I have to acknowledge my present setup is perfectly adequate and just be happy. It would be completely unreasonable not to be able to enjoy the quality of audio replay generally available today. Well, at least relative to what I grew up with. I'll follow your advice concerning conversions.
Thanks and best regards,
John.

More audio tomfoolery
 

In article , John R Leddy
wrote:
From what I've read on the web, recent remasters don't guarantee much
anyway.

It depends on your taste in music. But in general I hold the BBC's Radio 3
in high regard. There are slips, but their output is generally well
engineered. With the Proms approaching the iplayer 320k stream is your
friend. And with luck get_iplayer will continue to work during the Proms.

And I wasn't surprised to find that Decca CDs tended to be better made than
EMI ones. EMI were always crap at LP, and I often felt their CDs sounded
worse than Decca/Philips ones even when I couldn't say *why*. Now, I guess
I can.

Remasters like the Decca War Requiem are excellent. [1]So too are the 'EMI'
ones which were re-released on SACD/CD dual-layer disc sets. These included
the best versions of the Barbirolli/duPre/Baker Elgar cello con, Sea Pics,
etc, that I've heard.

Problem is that it can be pot luck. e.g. many BBC Music Magazine cover
discs are very good. But some have problems. e.g. a recent Verdi requiem
shows ADC/processing flaws. And a while ago they produced CDs with the
pre-emphasis flag bit 'on' when the audio isn't pre-emphasised. Slip
somewhere when someone 'improved' something.

Jim

[1] Their 96k/24 flac of the Britten Peter Grimes is also good. Don't know
if the Billy Budd is released.

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
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More audio tomfoolery
 

On 15/07/2015 16:32, Jim Lesurf wrote:

shows ADC/processing flaws. And a while ago they produced CDs with the
pre-emphasis flag bit 'on' when the audio isn't pre-emphasised. Slip
somewhere when someone 'improved' something.

If you copy it to .wav files, then write them to another CD,
you will probably fix that. Do you have any examples?
Something I might have in my collection?

On the other hand, if you 'rip' a CD with pre-emphasis,
it will probably have 10dB of HF boost.

--
Eiron.

More audio tomfoolery
 

In article , Eiron
wrote:
On 15/07/2015 16:32, Jim Lesurf wrote:

shows ADC/processing flaws. And a while ago they produced CDs with the
pre-emphasis flag bit 'on' when the audio isn't pre-emphasised. Slip
somewhere when someone 'improved' something.

If you copy it to .wav files, then write them to another CD,
you will probably fix that. Do you have any examples?
Something I might have in my collection?

I did make a list of the BBC Music Mag examples I found. Just found it in
my lab-book.

Examples include Vol 18 numbers 10, 11, 12 Vol 19 number 1, 2 , 4, 5, 6,
9, 10, 12. Volume 20 numbers 1, 2.

There may be others as I didn't check every disc and some I didn't buy. (I
don't bother with Xmas/Easter compilations for example.) Just buy issues
when the cover disc looks interesting.

I did email the person who was doing the mastering. They replied at first,
but then ceased doing so when I asked about the specific problem. So I
can't tell if they had no idea what I was talking about, or simply didn't
want to admit to making an error.

Didn't note the titles/works, just the magazine volume and issue.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html