On 08/09/2014 03:16, Johny B Good wrote:
On Sun, 07 Sep 2014 16:44:21 +0100, Jim Lesurf
wrote:

In article , Don Pearce
wrote:
On Sun, 07 Sep 2014 14:33:16 GMT, (Don Pearce) wrote:

On Sun, 07 Sep 2014 15:03:37 +0100, Jim Lesurf
wrote:



Jim, I don't know if you can watch Youtube, but here's a short clip on
the manual repair process.

So far I've not bothered with YouTube TBH.

However the problem I'm interested in is any algorithm for *finding* (and
listing the positions of) clicks and ticks. The repair is the easy part,
although I'd always do that manually so I can the waveform before and
after. Sometimes a careless repair is worse that the original. :-)

snip

I soon developed a strategy for dealing with such
de-clicking/de-popping processing. Essentially, scan the whole
waveform by eye for any loud obvious spikes, home in on them to
ascertain what they actually are, select a narrow window bracketing
the click and apply the declick filter, check the result was
acceptable, undoing it if need be and try again with different
parameters or else hand edit the samples or even simpler for a very
short transient (around 1 ms or less), snip out that section entirely.
Repeat and rinse until the whole waveform was cleared of major clicks
and pops before applying normalisation (always, of course, auditioning
such edits before moving onto the next).

snip

Yep, that's more or less what I've done. I'd also 'sew' the wave in
something like Audition, and remove the peak. Only takes a couple of
seconds.

However, I'd only tend to get involved at that level with scratches.
Which of course are considerably easier because they pop (ha) up at
fixed intervals.

For crackle and pop a decent clean, and live with what's left. Adds to
the ambience :-)


--
Cheers, Rob

In article , Johny B Good
wrote:
On Sun, 07 Sep 2014 16:40:06 +0100, Jim Lesurf
wrote:

I do recall, however, that I tended to avoid auto repair

So far I've avoided it entirely and intend to go on doing so. My interest
at this point is wrt assessing how to generate a 'list' of locations which
may have a click. Then examining them and making the decision, case by
case, and using manual methods as and when I think needed for each example.





I think you're already getting a notion of what I was going on about
two paragraphs back. I think we all start off with an idealistic zeal
for 'perfection' (at least that was true enough in my case) before the
realism kicks in when the enormity of the task finally sinks in.

Well I knew from the start that my default was to do no click editing at
all unless I felt it was needed as a 'special case'.

So far I've done hundreds of my old LPs and not bothered with any click
removal. All I've done is some snipping of long lead ins or outs. Plus
doing things like making mono files if the discs was mono.

In practice most of my LPs are ones I bought decades ago. I would then
return any with bad defects to the shop for a replacement. Then kept them
carefully. So they are generally fairly free of annoying defects because of
the effort I went to to avoid them back then!

More recently I've been experimenting with buying some 2nd hand LPs. I
found a source of cheap Jazz LPs and many of these are close to being free
of audible clicks. Many are things like the old RCA 'Black and White' or
'Tribune' ones transferred in the 1970s from 78s. So they have lots of
surface noise anyway. Hence no real need to de-click them at all.

However I've also experimented with a few Classical LPs 2nd hand and found
some that were as 'good as new'. But of course some others aren't. If they
are poor and run-of-the-mill content I just write them off as a donation to
charity. :-)

But a *few* LPs have a special status from my POV. Three examples:

Play Bach No 1. Teldec pressing. This is a *superb* recording. Makes a good
test LP for the tracking ability of my V15 as well! In general no clicks or
ticks. But it did have some. So I decided to clean them away. The result is
very nice indeed.

Barbirolli EMI LP of Sibelius Tone Poems. Superb recording and music. But
lots of clicks. Since I love the sound of this I spent time removing all
the clicks I could deal with with. Again, excellent results.

Beethoven Triple Concerto. Oistrakh/Richter/Rostropovich. Like the
Barbirolli.

These are examples of digital transfers I expect to play often as they are
so good. LPs I only play rarely seem less worth working on.

Just deal with the most obvious defects and leave the rest for future
generations to deal with when they might have access to better tools by
which to complete the task. After all, you've already completed the most
important task of digitising it in the first place even if you never
process it any further than topping and tailing the tracks.

Indeed. With most of my transfers I've adopted the view that I can 'fix
them later if I really want to'.

However being able to generate a *reliable* list of most of the audible
click locations would speed up both the decision about how much work - if
any - to do, and how long that work then takes. The loud clicks and bangs
are easy to decide about.

The problem with the smaller ticks is *finding* them to be able to deal
with them. Fixing them is easy and quick *once* I've located them. So
automating the location process is what would save time. In turn that would
make it easier to do more discs, more thoroughly. But I know I'm asking
what may be an impossible question. I have no problem with the 'fixing'.
Just with *finding* the damn things when they can 'hide' in the music
waveforms.

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

Well, not totally free, but I've had good results with Goldwave. I let it
loose on its passive setting first, and this gets rid of the most annoying
ones. Then you have the issue you describe.
What I tend to do now is to decide by temporarily doing a part I've copied
out in several ways and see what sort of effect I get.
If the record is sizzling, ie the clicks are many, trying to do the
substitution usually results in an audibly worse effect such as a gurgle in
the sound due to so many repeated samples. If its just an od one or a thud,
sometimes using a more aggressive targeted process in that region can help.
Not always though. Suck it an see.
Thuds are the worst in my view, as no way to detect them. The very
committed might look at the waveform and manually mess with it, but is it
really worth it?
I do also clean the record with warm water and fairy liquid in a Knowin
cleaner and play them wet, as this reduces surface noise and puts a lot of
the much in suspension. Make sure the stylus is cleaned though as a mess of
dried crap tends to build up!
Surface noise and rumble.
This process really depends on how much its annoying. Often very light
noise reduction can be a help though in quieter areas, it can make the sound
have a watermark of the noise in it making it sound a little odd.
I tend to only use this if its really needed in the quiet areas, and do not
use it on the loud bits as it is masked.
Fade outs show the adverse effects. Goldwave allows you to tweak the
overlap and the Fourier transform parameters to make it as inaudible as
possible on a test area.

It can be quite time consuming of course but can make some remarkably good
sounding results.
I rejected audacity as it was not up to the job, but each to their own.
The goldwave I use is the old version not the new multi track all singing
and dancing one.
Brian


--
From the Sofa of Brian Gaff Reply address is active
"Jim Lesurf" wrote in message
...
I've recently been experimenting with using Audacity to deal with clicks
in
digital recordings made from old LPs. I suspect I'm not the first to do
this or encounter the following! Hence I'd be interested in feedback on
what follows...

LPs in very good condition only have a few clicks, and these can be easy
enough to find and fix. Particulary if they are loud 'rifle shots' that
stick out clearly on something like Audacity's waveform plots!

However other LPs can have many many clicks per LP side. This can make
finding and fixing most of them fairly time-consuming. In particular when
a
small 'tick' is hiding as a small alternation to a larger and complex
audio
waveform. It becomes a bit like looking for a sapling in a forest! For
some
old classical LPs there may be lots of these which are audible as the
music
can have long low-level sections, meaning that clicks it would be
impossible to hear with loud Jazz, say, show up against quiet classical.

Because of this I've been experimenting with ways to scan a wave file
looking for clicks. Using tricks like looking at the first or second
derivative of the waveforms which appear rise and fall quckly to emphasise
short sharp clicks out of the steady music background. However I'm
wondering about two things.

1) Anyone know of decent free software that already does something like
this well and can list a good set of 'click candidate' times in a wave
file. i.e. low levels of 'misses' and 'false alarms' even with classical
music.

2) To what extent this is simply a waste of effort beyond finding the most
obvious clicks. i.e. That there isn't a simple and reliable algorithm for
this and it ends up being quicker and better to use ears and eyes and
Audacity.

So far I have the impression that (2) comes into force pretty quickly as
the clicks vanish into the waveforms. But I thought I'd ask as I suspect
others have explored this already. :-)

BTW At present simply using ear/eye/Audacity I seem to find that the 'hard
cases' where I'm searching for many tiny 'ticks' can mean about 0.1 rate
working. i.e. About 200 - 300 mins of work per LP side for classical if I
really want to clear even the faintest ticks I hear. Fortunately, LPs that
tend to spend most of the time at higher levels are much quicker as the
music drowns out the smaller ticks.

BTW2 Having experimented I haven't found the declicking 'effect' of
Audacity to be much use. I've just been using the 'repair' instead. But
maybe I'm missing something here...

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

Snipped

The situation seems to have improved somewhat over recent years, at
least as far as recently manufactured MoBos and USB adapters are
concerned. I don't know how long it took before the industry finally
spotted their "Schoolboy Howler" and corrected the design. I suspect
it took something like a decade for them to finally sit up and take
notice.


FWIW.. This company specialised in 78 restoration and developed systems
to do that some time ago now..

http://www.cedar-audio.com/
--
Tony Sayer

Jim Lesurf wrote:

1) Anyone know of decent free software that already does something
like this well and can list a good set of 'click candidate' times in
a wave file. i.e. low levels of 'misses' and 'false alarms' even with
classical music.

Try AFDeClick

http://www.andreas-flucke.homepage.t...index_eng.html

It might help to understand what (and what not) it does ...

http://www.andreas-flucke.homepage.t...ick/about.html

Anyway, like I mentioned above, just try.

Keep on rocking.

Muck

On 2014-09-07, Jim Lesurf wrote:
I've recently been experimenting with using Audacity to deal with clicks in
digital recordings made from old LPs. I suspect I'm not the first to do
this or encounter the following! Hence I'd be interested in feedback on
what follows...

LPs in very good condition only have a few clicks, and these can be easy
enough to find and fix. Particulary if they are loud 'rifle shots' that
stick out clearly on something like Audacity's waveform plots!

However other LPs can have many many clicks per LP side. This can make
finding and fixing most of them fairly time-consuming. In particular when a
small 'tick' is hiding as a small alternation to a larger and complex audio
waveform. It becomes a bit like looking for a sapling in a forest! For some
old classical LPs there may be lots of these which are audible as the music
can have long low-level sections, meaning that clicks it would be
impossible to hear with loud Jazz, say, show up against quiet classical.

Because of this I've been experimenting with ways to scan a wave file
looking for clicks. Using tricks like looking at the first or second
derivative of the waveforms which appear rise and fall quckly to emphasise
short sharp clicks out of the steady music background. However I'm
wondering about two things.

1) Anyone know of decent free software that already does something like
this well and can list a good set of 'click candidate' times in a wave
file. i.e. low levels of 'misses' and 'false alarms' even with classical
music.

2) To what extent this is simply a waste of effort beyond finding the most
obvious clicks. i.e. That there isn't a simple and reliable algorithm for
this and it ends up being quicker and better to use ears and eyes and
Audacity.

So far I have the impression that (2) comes into force pretty quickly as
the clicks vanish into the waveforms. But I thought I'd ask as I suspect
others have explored this already. :-)

BTW At present simply using ear/eye/Audacity I seem to find that the 'hard
cases' where I'm searching for many tiny 'ticks' can mean about 0.1 rate
working. i.e. About 200 - 300 mins of work per LP side for classical if I
really want to clear even the faintest ticks I hear. Fortunately, LPs that
tend to spend most of the time at higher levels are much quicker as the
music drowns out the smaller ticks.

BTW2 Having experimented I haven't found the declicking 'effect' of
Audacity to be much use. I've just been using the 'repair' instead. But
maybe I'm missing something here...

Apparently my response never got posted. So try again.

Clicks are caused by defects on the record. beween the cartridge and the
output is the RIAA filter, which is essentially an integrator (actually
and integrator followed by a high frequency single pole boost). This
means that a sudden displacement of the stylus back and forth, gets
converted into what is essentially a step funtion-- ie the effect of the
click gets distributed in time.

Thus what one wants to do is to apply an inverse RIAA curve to the
output and look at the the result. The clicks should now be far more
localised-- ie their effect should be far more concentrated, and
removeable. Ie, apply the inverse RIAA (essentially a differentiation
followed by a bass boost-- Ie, flat to 500 Hz, then a fall at 6dB/octave
to 2000 Hz, and then flat again above that if I remember the RIAA
correctly.) note that this means that there is a total of about 50dB
change from low freq to high, which means that you have to be using at
least 24bit, and preferaqbley 32 bit processing of the signal in order
not to get clipping, or introduce excess noise.

So use sox say to impliment the inverse RIAA, then use audacity to look
for those spikes, and remove them, then use the RIAA on the result.
Note that one could just take the derivative, but that would still leave
a finite spreading due to the treble/bass boost.


Jim

Sometimes playing it backwards for detection actually works better than
forwards.
Brian

--
From the Sofa of Brian Gaff Reply address is active
"William Unruh" wrote in message
...
On 2014-09-07, Jim Lesurf wrote:
I've recently been experimenting with using Audacity to deal with clicks
in
digital recordings made from old LPs. I suspect I'm not the first to do
this or encounter the following! Hence I'd be interested in feedback on
what follows...

LPs in very good condition only have a few clicks, and these can be easy
enough to find and fix. Particulary if they are loud 'rifle shots' that
stick out clearly on something like Audacity's waveform plots!

However other LPs can have many many clicks per LP side. This can make
finding and fixing most of them fairly time-consuming. In particular when
a
small 'tick' is hiding as a small alternation to a larger and complex
audio
waveform. It becomes a bit like looking for a sapling in a forest! For
some
old classical LPs there may be lots of these which are audible as the
music
can have long low-level sections, meaning that clicks it would be
impossible to hear with loud Jazz, say, show up against quiet classical.

Because of this I've been experimenting with ways to scan a wave file
looking for clicks. Using tricks like looking at the first or second
derivative of the waveforms which appear rise and fall quckly to
emphasise
short sharp clicks out of the steady music background. However I'm
wondering about two things.

1) Anyone know of decent free software that already does something like
this well and can list a good set of 'click candidate' times in a wave
file. i.e. low levels of 'misses' and 'false alarms' even with classical
music.

2) To what extent this is simply a waste of effort beyond finding the
most
obvious clicks. i.e. That there isn't a simple and reliable algorithm for
this and it ends up being quicker and better to use ears and eyes and
Audacity.

So far I have the impression that (2) comes into force pretty quickly as
the clicks vanish into the waveforms. But I thought I'd ask as I suspect
others have explored this already. :-)

BTW At present simply using ear/eye/Audacity I seem to find that the
'hard
cases' where I'm searching for many tiny 'ticks' can mean about 0.1 rate
working. i.e. About 200 - 300 mins of work per LP side for classical if I
really want to clear even the faintest ticks I hear. Fortunately, LPs
that
tend to spend most of the time at higher levels are much quicker as the
music drowns out the smaller ticks.

BTW2 Having experimented I haven't found the declicking 'effect' of
Audacity to be much use. I've just been using the 'repair' instead. But
maybe I'm missing something here...

Apparently my response never got posted. So try again.

Clicks are caused by defects on the record. beween the cartridge and the
output is the RIAA filter, which is essentially an integrator (actually
and integrator followed by a high frequency single pole boost). This
means that a sudden displacement of the stylus back and forth, gets
converted into what is essentially a step funtion-- ie the effect of the
click gets distributed in time.

Thus what one wants to do is to apply an inverse RIAA curve to the
output and look at the the result. The clicks should now be far more
localised-- ie their effect should be far more concentrated, and
removeable. Ie, apply the inverse RIAA (essentially a differentiation
followed by a bass boost-- Ie, flat to 500 Hz, then a fall at 6dB/octave
to 2000 Hz, and then flat again above that if I remember the RIAA
correctly.) note that this means that there is a total of about 50dB
change from low freq to high, which means that you have to be using at
least 24bit, and preferaqbley 32 bit processing of the signal in order
not to get clipping, or introduce excess noise.

So use sox say to impliment the inverse RIAA, then use audacity to look
for those spikes, and remove them, then use the RIAA on the result.
Note that one could just take the derivative, but that would still leave
a finite spreading due to the treble/bass boost.


Jim

On Wed, 10 Sep 2014 09:19:44 +0100, "Brian Gaff"
wrote:

Sometimes playing it backwards for detection actually works better than
forwards.
Brian

In the digital world, the idea of playing in any direction has no
meaning - you don't detect steep edges that way, you differentiate and
look at amplitude.

d

In article , William Unruh
wrote:
On 2014-09-07, Jim Lesurf wrote:
[snip]

I understand the argument about RIAA being quasi-integrating, etc. Its one
of the reasons behind my thinking that looking at the first or second
derviative would help.

So use sox say to impliment the inverse RIAA, then use audacity to look
for those spikes, and remove them, then use the RIAA on the result.
Note that one could just take the derivative, but that would still leave
a finite spreading due to the treble/bass boost.

Wary of that because 'mending' a differential waveform might lead to a dc
offset problem when you re-integrate the result. So I'd use a dx/dt or
d2x/d2t to *find* and list click locations. But do any editing on the
actual audio file recorded using RIAA. Avoids the problems of dealing with
the real response curve being rather complicated.

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

In article , Muck Krieger
wrote:
Jim Lesurf wrote:

1) Anyone know of decent free software that already does something
like this well and can list a good set of 'click candidate' times in a
wave file. i.e. low levels of 'misses' and 'false alarms' even with
classical music.

Try AFDeClick

http://www.andreas-flucke.homepage.t...index_eng.html

It might help to understand what (and what not) it does ...

http://www.andreas-flucke.homepage.t...ick/about.html

Anyway, like I mentioned above, just try.

The above says it uses an 'algorithm' but gives no details of the algorithm
itself. Its also just a DOS exc when downloaded. No added info on the
program itself. When processing data I like to know the details of the
process. Have a dislike of 'black boxes'... :-)

I also use RO and Linux. Gave up any Windows use years ago, and don't
bother with Wine, etc. Life's too short. :-) It also seems to just 'fix
the clicks' rather than generate a list of candidate instants for me to
examine and decide upon.

FWIW Even the simple 'click lister' I wrote as a quick experiment seems to
find the main click events without too much trouble. That's just using
rapid falls in peak level. The challenge is smaller ticks which hide in the
audio. So, when I can, I'll have a go at a program using differentiation
first and see how I get on. The files I record are 96k/24 BTW.

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