In article , Meindert
Sprang wrote:
"Jim Lesurf" wrote in message
...
Like others, I'd suggest *avoiding* normalizing or limiting to
anything close to 0dBFS. if you normalise to within a dB or so of
0dBFS you'd need to check any CD player you use can then handle
intersample excursions produced by the DAC/reconstruction filter that
rise above 0dBFS.

Is that *really* an existing problem ur an urban myth?

I can't say for all players. But when I was investigating this area for Hi
Fi News a few years ago one of the people there I was discussing it with
did some checks on some then-current players that he had. The measured
results showed that some of them did alter/distort waveform excursions
above 0dBFS due to intersample peaks.


The Red Book specifies 16 bit data. Why would they do that if a player
would not be able to reconstruct full 16 bit data to an analog signal?

The snag here is the usual one.

In theory, theory and practice agree. But in practice they may not... at
least some of the time.

to me this would really be a severe design flaw in a CD player! If I
were the designer of a DAC and I would expect that an interpolation
between two samples would rise above the maximum dynamic range, I'd add
the necessary bits to take care of that or scale the input of that
process down. In my DSP work I always checked the input range and output
range of calculations to see if it would fit in the 'width' of
calculations and scale accordingly. This is standard design practice.

For me, also. But any finite state system with finite value representations
will have a limit, And the evidence is that some designers haven't catered
for this.

For a CD player you should only need one more bit as the max possible
overshoot is of the order of 3dB so far as I was able to determine. Not a
very demanding requirement, but still needs to be implimented into the
design.

So a *good* designer making a *good* machine will allow for intersample
peaks. But are all designers and machines "good"?...

And given how clipped some pop/rock CDs are, how much difference would it
make given what has been done to the music before the player reads it from
the disc?!

I'll see if I can find the data and I'll ask the person who gave it to me
if he minds it being made public. At the time it was just sent to me as
part of our discussions about the topic.

One of the related discussions I've had with others is the speculation that
'NOS' DACs and players may be liked by some people because they avoid this
by having no digital values generated in between input samples, and can
have a following analogue filter for reconstruction that can cope with the
peaks.

Slainte,

Jim

--
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

In article ,
Meindert Sprang wrote:
"Jim Lesurf" wrote in message
...
Like others, I'd suggest *avoiding* normalizing or limiting to anything
close to 0dBFS. if you normalise to within a dB or so of 0dBFS you'd need
to check any CD player you use can then handle intersample excursions
produced by the DAC/reconstruction filter that rise above 0dBFS.

Is that *really* an existing problem ur an urban myth?

It does exist on a few model players.

The Red Book
specifies 16 bit data. Why would they do that if a player would not be able
to reconstruct full 16 bit data to an analog signal?

Because the Red Book was written before any of the players existed.

to me this would really
be a severe design flaw in a CD player! If I were the designer of a DAC and
I would expect that an interpolation between two samples would rise above
the maximum dynamic range, I'd add the necessary bits to take care of that
or scale the input of that process down. In my DSP work I always checked the
input range and output range of calculations to see if it would fit in the
'width' of calculations and scale accordingly. This is standard design
practice.

Consumer equipment is designed to be as cheap as absolutely possible.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

In article , Scott Dorsey
wrote:

Consumer equipment is designed to be as cheap as absolutely possible.
--scott

My take on that is slightly different. That consumer equipment is made to
be *sold* (at a profit), not to be *used*. Some designers/makers may be
more concerned for the end-user (rather than customer) than others. But I'm
not sure price is always a good indicator...

Slainte,

Jim

--
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

"hank alrich" wrote in message
...
Sean Conolly wrote:

* Normalize & hard limit (if needed) to the final levels I want for CD. I
hard limit sparingly, just enough to bring up the average level if
there's a
few peaks that stand out.
* Convert to 16 bit for burning to CD

Why in the world would you hard limit when moving from a medium with
maybe 50 or 60 dB of dynamic range to one of 96 dB of dynamic range?

Simply to somewhat match the levels of the other material on the CD, so I'm
not adjusting the levels per song when I'm listening. Just my own
preference.

Trimming a few DB off a few transients is inaudible. Shaving the entire
track like a lawnmower is not the idea, but as you know is a common (and
bad) practice.


Significant peaks probably didn't survive recording to cassette in the
first place.

Agreed.

Sean

"Meindert Sprang" wrote in message
...
"Jim Lesurf" wrote in message
...
Like others, I'd suggest *avoiding* normalizing or limiting to anything
close to 0dBFS. if you normalise to within a dB or so of 0dBFS you'd need
to check any CD player you use can then handle intersample excursions
produced by the DAC/reconstruction filter that rise above 0dBFS.

Is that *really* an existing problem ur an urban myth? The Red Book
specifies 16 bit data. Why would they do that if a player would not be
able
to reconstruct full 16 bit data to an analog signal? to me this would
really
be a severe design flaw in a CD player! If I were the designer of a DAC
and
I would expect that an interpolation between two samples would rise above
the maximum dynamic range, I'd add the necessary bits to take care of that
or scale the input of that process down. In my DSP work I always checked
the
input range and output range of calculations to see if it would fit in the
'width' of calculations and scale accordingly. This is standard design
practice.

No, it's a legitmate problem with some gear, and I'm inclined to agree with
Jim on why.

For demos that I'm going to distribute I set the peaks to -1 db, which is
fine with all the players I've encountered.

Sean

Scott Dorsey wrote:

Consumer equipment is designed to be as cheap as absolutely possible.

Some is, and some is designed to be as expensive as absolutely possible, on
the hope that there will be a fool who pays the money. And then there is
us, in a range across the middle, with slightly varying criteria.

geoff

"geoff" wrote in message
...
Scott Dorsey wrote:
Consumer equipment is designed to be as cheap as absolutely possible.

Some is, and some is designed to be as expensive as absolutely possible,
on the hope that there will be a fool who pays the money.

Nope, that is still designed to be as cheap as possible *for the
manufacturer* (obviously NOT for the purchaser) so the manufacturer can
spend money on advertising a very low volume item whilst still making a very
large profit.

Trevor.

Trevor wrote:
"geoff" wrote in message
...
Scott Dorsey wrote:
Consumer equipment is designed to be as cheap as absolutely
possible.

Some is, and some is designed to be as expensive as absolutely
possible, on the hope that there will be a fool who pays the money.

Nope, that is still designed to be as cheap as possible *for the
manufacturer* (obviously NOT for the purchaser) so the manufacturer
can spend money on advertising a very low volume item whilst still
making a very large profit.

Trevor.

And you can buy a high-priced Loewe that is actually LG inside a pretty box
!

geoff

In article , Jim Lesurf
wrote:

[snip discussion of players distorting inter-sample peaks]

I'll see if I can find the data and I'll ask the person who gave it to
me if he minds it being made public. At the time it was just sent to me
as part of our discussions about the topic.

He has just replied and said this is OK. So I'll publish his results on my
website when I get a 'round tuit'. :-)

Slainte,

Jim

--
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

On 23 Jul, wrote:
In article , Jim Lesurf
wrote:

[snip discussion of players distorting inter-sample peaks]

I'll see if I can find the data and I'll ask the person who gave it to
me if he minds it being made public. At the time it was just sent to
me as part of our discussions about the topic.

He has just replied and said this is OK. So I'll publish his results on
my website when I get a 'round tuit'. :-)

I've now done this and the results can be seen at

http://www.audiomisc.co.uk/HFN/OTTre...d/results.html

My thanks to Keith Howard for kindly agreeing to let me publish his
measured results. Note they were made in 2007 so only covered the players
and DACs he had to hand at that time. But - rather depressingly - all but
one of the nine he tried showed they had problems coping with the waveform
that has peaks at +3dBFS.

FWIW personally I'd love to see all reviews on DACs or player use the
'waveform from hell' I devised for the original article (a link to that is
on the above page) as a test of how they cope - or not! :-) I have the
uncomfortable feeling that whilst reviews continue to overlook this area,
problems will continue to afflict some new designs without anyone knowing.

Slainte,

Jim

--
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