Noise Shaping for high rez files and streams
 

"Dave Plowman (News)" wrote in message
...
In article ,
Phil Allison wrote:
Brian-Gaff wrote:

In the very start of digital some recordings looked fantastic on specs
but sounded crap, seeming like they had some kind of noise gate on
them. then came dither, which made recordings sound right again. I'll
just leave this hanging there....




** One of the first CDs I bought was of solo classical piano on the
Erato label. At the end of each track, as the final note faded down it
turned into a fizzing sound. This was noticeable at other quiet times
too.

It was also common practice on early CDs made from older analogue tapes to
have a steeper fade out at the end of a track than on the original vinyl
so you got silence between tracks. Never did see the point of that.

Tracks on analogue tapes are separated by a
three second leader (silence) so no fade of any kind
is required for either lacquer or CD mastering.

But, the 30dB lower noise floor on CD may have
given you that impression.


Iain

Noise Shaping for high rez files and streams
 

"Vir Campestris" wrote in message
o.uk...
On 17/02/2017 09:42, Iain Churches wrote:
A bad pressing? I like that :-))

I did have one once. It so happened we had a CD tester at work, and it
showed multiple errors scattered all over the surface. I contacted the
manufacturer, and they sent me a new disc. Pressed somewhere else... I
don't know if they did anything with the tester report I sent them.

:-))

Did the multiple errors affect the replay, or prevent
the disc from playing? Quite often they do not.

CD plants produce in "lines", so the replacement disc does
not have to be made somewhere else just on a different line.

A Reed Solomon reader (probably like the one you had at
work) is used for QC. One of these two gentlemen
(Reed or Solomon) is quoted as saying "without error
correcting codes digital audio would not be technically
feasible"

Iain

Noise Shaping for high rez files and streams
 

On 18/02/2017 12:00, Iain Churches wrote:
"Vir Campestris" wrote in message
o.uk...
On 17/02/2017 09:42, Iain Churches wrote:
A bad pressing? I like that :-))

I did have one once. It so happened we had a CD tester at work, and it
showed multiple errors scattered all over the surface. I contacted the
manufacturer, and they sent me a new disc. Pressed somewhere else... I
don't know if they did anything with the tester report I sent them.

:-))

Did the multiple errors affect the replay, or prevent
the disc from playing? Quite often they do not.

CD plants produce in "lines", so the replacement disc does
not have to be made somewhere else just on a different line.

A Reed Solomon reader (probably like the one you had at
work) is used for QC. One of these two gentlemen
(Reed or Solomon) is quoted as saying "without error
correcting codes digital audio would not be technically
feasible"

Which is complete bollox.

Anyway, a CD will play perfectly even after drilling a few 2mm holes in it.

--
Eiron.

Noise Shaping for high rez files and streams
 

On Sat, 18 Feb 2017 14:21:48 +0000, Eiron
wrote:

On 18/02/2017 12:00, Iain Churches wrote:
"Vir Campestris" wrote in message
o.uk...
On 17/02/2017 09:42, Iain Churches wrote:
A bad pressing? I like that :-))

I did have one once. It so happened we had a CD tester at work, and it
showed multiple errors scattered all over the surface. I contacted the
manufacturer, and they sent me a new disc. Pressed somewhere else... I
don't know if they did anything with the tester report I sent them.

:-))

Did the multiple errors affect the replay, or prevent
the disc from playing? Quite often they do not.

CD plants produce in "lines", so the replacement disc does
not have to be made somewhere else just on a different line.

A Reed Solomon reader (probably like the one you had at
work) is used for QC. One of these two gentlemen
(Reed or Solomon) is quoted as saying "without error
correcting codes digital audio would not be technically
feasible"

Which is complete bollox.

Anyway, a CD will play perfectly even after drilling a few 2mm holes in it.

Yup, and the reason it will is the error correction, specifically
trellis coding that splits a byte up into individual bits then dots
them all over the place so something like a hole won't destroy
complete bytes which would be hard to rebuild. The R&S coding plus a
heap of redundancy means you can reassemble valid data from some
pretty awful damage. They are right that not many CDs would survive
more than a few plays and still be readable without this error
correction.

d

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Noise Shaping for high rez files and streams
 

In article , Don Pearce
wrote:
Which is complete bollox.

Anyway, a CD will play perfectly even after drilling a few 2mm holes in
it.

Yup, and the reason it will is the error correction, specifically
trellis coding that splits a byte up into individual bits then dots them
all over the place so something like a hole won't destroy complete bytes
which would be hard to rebuild. The R&S coding plus a heap of redundancy
means you can reassemble valid data from some pretty awful damage.

Yes. Something I've been confirming over the last few days. c.f 'aside'
below...

They are right that not many CDs would survive more than a few plays and
still be readable without this error correction.

Not sure what you meant there. A conventionally made CD (i.e. not a CD-R/W)
shouldn't be degraded by being played a few times.

Aside:

A couple of days ago a musician we know brought a CDR they'd got from a
recent concert they'd made being recorded. This was covered with gunk which
took some cleaning off before it would play reliable even in some Audio CDR
players I use. It then played despite having an obvious 'hole' in the
polycarb covering one part of the disc. Fortunately the hole is smaller
than a mm or so.

But the disc was clearly still 'difficult' as one of the Audio CDR machines
players still a fuss about reading the TOC and deciding what it was. (The
other was happy.) Similarly, an experimental try and ripping it see what
I'd get using a standard drive in my main Linux box struggled.

However the drive in my RISC OS box read it, no worries. I used two
different ripping processes and the results, when compared, were
bit-identical. So I have now edited one work to have a track per movement.

I suspect the disc was written at far too high a rate as well as then
having been covered in gunk.

FWIW I also noticed that the recording has peaks that go right up to within
a gnat's crotchet of clipping. So I'll try and find out more about who
recorded it and if there is a source version to compare with. Curious to
see what I can find out.

However all the Audio CDRs I'd written a decade or so ago continue to be
playable with no problems - although I have now transferred almost all to
flac files anyay.

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

Noise Shaping for high rez files and streams
 

On Sat, 18 Feb 2017 16:58:17 +0000 (GMT), Jim Lesurf
wrote:

They are right that not many CDs would survive more than a few plays and
still be readable without this error correction.

Not sure what you meant there. A conventionally made CD (i.e. not a CD-R/W)
shouldn't be degraded by being played a few times.

I was really referring to the random little marks and scratches that a
CD accumulates in less-than-careful hands. Without error correction
even minor marks make a CD unplayable.

d

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Noise Shaping for high rez files and streams
 

"Eiron" wrote in message
...
On 18/02/2017 12:00, Iain Churches wrote:
"Vir Campestris" wrote in message
o.uk...
On 17/02/2017 09:42, Iain Churches wrote:
A bad pressing? I like that :-))

I did have one once. It so happened we had a CD tester at work, and it
showed multiple errors scattered all over the surface. I contacted the
manufacturer, and they sent me a new disc. Pressed somewhere else... I
don't know if they did anything with the tester report I sent them.

:-))

Did the multiple errors affect the replay, or prevent
the disc from playing? Quite often they do not.

CD plants produce in "lines", so the replacement disc does
not have to be made somewhere else just on a different line.

A Reed Solomon reader (probably like the one you had at
work) is used for QC. One of these two gentlemen
(Reed or Solomon) is quoted as saying "without error
correcting codes digital audio would not be technically
feasible"

Which is complete bollox.

Anyway, a CD will play perfectly even after drilling a few 2mm holes in
it.

Indeed it will.
It is the error correction which makes that possible.

Do you remember Keith G who was one of the more
"interesting" subscribers to this group some years back?
When the drilling of small holes in CDs, and the fact that
they still played, was mentioned. He wrote: "That' nothing!
Every LP I own has a much bigger hole, and right through the
centre. The only error correction they have is an occasional
wipe with a DustBug. and they all play perfectly"

:-)

Iain

Noise Shaping for high rez files and streams
 

On 18/02/2017 12:00, Iain Churches wrote:
Did the multiple errors affect the replay, or prevent
the disc from playing? Quite often they do not.

I only put it in the tester because I had so much trouble playing it.

CD plants produce in "lines", so the replacement disc does
not have to be made somewhere else just on a different line.

The format of the ID number in the centre was different. I suspect a
different plant.

A Reed Solomon reader (probably like the one you had at
work) is used for QC. One of these two gentlemen
(Reed or Solomon) is quoted as saying "without error
correcting codes digital audio would not be technically
feasible"

It would give back analogue level data - pit/land lengths and
reflectivity, that sort of stuff - as well as the number of corrected
and uncorrectable errors. It was also stupidly expensive. My memory has
failed me though, and I can't recall the name!

Andy

Noise Shaping for high rez files and streams
 

In article , Iain Churches
scribeth thus

"Eiron" wrote in message
...
On 18/02/2017 12:00, Iain Churches wrote:
"Vir Campestris" wrote in message
o.uk...
On 17/02/2017 09:42, Iain Churches wrote:
A bad pressing? I like that :-))

I did have one once. It so happened we had a CD tester at work, and it
showed multiple errors scattered all over the surface. I contacted the
manufacturer, and they sent me a new disc. Pressed somewhere else... I
don't know if they did anything with the tester report I sent them.

:-))

Did the multiple errors affect the replay, or prevent
the disc from playing? Quite often they do not.

CD plants produce in "lines", so the replacement disc does
not have to be made somewhere else just on a different line.

A Reed Solomon reader (probably like the one you had at
work) is used for QC. One of these two gentlemen
(Reed or Solomon) is quoted as saying "without error
correcting codes digital audio would not be technically
feasible"

Which is complete bollox.

Anyway, a CD will play perfectly even after drilling a few 2mm holes in
it.

Indeed it will.
It is the error correction which makes that possible.

Do you remember Keith G who was one of the more
"interesting" subscribers to this group some years back?
When the drilling of small holes in CDs, and the fact that
they still played, was mentioned. He wrote: "That' nothing!
Every LP I own has a much bigger hole, and right through the
centre. The only error correction they have is an occasional
wipe with a DustBug. and they all play perfectly"

:-)

Iain



Yes met him at home once bought a brace of QUAD II's off him. Was a real
character Keith he had a sort of bedroom with most of the gear in, all
units piled on top of each other not an audio purist by any means but
very much an enthusiast, and that in abundance!.


Been dead now some time, lovely bloke and his wife Swimm was she
called?..
--
Tony Sayer

Noise Shaping for high rez files and streams
 

"tony sayer" wrote in message
...
In article , Iain Churches

Do you remember Keith G who was one of the more
"interesting" subscribers to this group some years back?
When the drilling of small holes in CDs, and the fact that
they still played, was mentioned. He wrote: "That' nothing!
Every LP I own has a much bigger hole, and right through the
centre. The only error correction they have is an occasional
wipe with a DustBug. and they all play perfectly"

:-)
Yes met him at home once bought a brace of QUAD II's off him. Was a real
character Keith he had a sort of bedroom with most of the gear in, all
units piled on top of each other not an audio purist by any means but
very much an enthusiast, and that in abundance!.

Yes a hi-fi enthusiast in the real sense. We never met,
but corresponded regularly. I got the impression
he was a very practical chap, good at carpentry,
and handy with the soldering iron. Quite rare
attributes for an audiophile in these plug-and-play
days.

He was interested in SET and FR speakers.
Such a system would have certainly
done justice to the kind of music he liked.

Unbeknown to Keith, I fixed him up with an invite to
a Lowther get-together. He told me: "Can ya believe it?
An invite right out of the blue, just arrived in the post"
He probably had an inkling, but I never let on:-).
He tucked some of his beloved recordings
under his arm, and went along, met some interesting
people, heard some fine music on some amazing
systems and by all account had a very good day.

Been dead now some time,
Five years.

lovely bloke and his wife Swimm was she
called?..

An acronym:-)
She is a very gifted pianist and clarinet player.

When I told Keith I was thinking about taking up the
saxophone, with a view to joining a band, he sent me
an .mp3 (from vinyl of course) of "Frankie and Johnny"
by the Count Basie Orchestra. He said, "It would
be great if you could play this" The band's second
CD "Mosaics" on which Frankie and Johnny (an accurate
transcription of the Basie original) is the opening title,
will be released this summer.

Keith would have been tickled pink :-)

Iain