Finding clicks
 

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. :-)

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

Finding clicks
 

On Sun, 07 Sep 2014 14:29:07 +0100, Jim Lesurf wrote:

LPs in very good condition only have a few clicks, and these can be easy
enough to find and fix.

Washing the record would be a good start.

Finding clicks
 

In article , mechanic
wrote:
On Sun, 07 Sep 2014 14:29:07 +0100, Jim Lesurf wrote:

LPs in very good condition only have a few clicks, and these can be
easy enough to find and fix.

Washing the record would be a good start.

I experimented with that a while ago. I found that it may have helped in
some cases, but in others it made no real difference.

Many of the clicks or ticks on old discs seem to be due to scratches or
wall damage.[1] Particularly for the 2nd hand discs. Overall, I decided the
time was better spent on de-clicking.

However I do carefully clean and prepare the discs before playing. Preener,
Zerostat, and the brush of a dust bug. Its a tedious ritual, but OK given
that from then on I'll use the cleaned digital file.

I've also learned the habit of listening carefully a multiple of 1.8 sec
after any tick... :-)

Jim

[1] Or for EMI discs in particular, scratches or dirt on the stamper for
discs made back circa 1970s.

--
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

Finding clicks
 

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. :-)

Jim

I think it is worth a look if you can find a way. The repair is not
the straightforward thing I thought it was.

d

Finding clicks
 

On 07/09/14 14:29, 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...

{...}

There is a Linux application called Gramofile which claims to do what
you want. I have used it in the past, but only for digitising
recordings, not de-clicking them. The software hasn't been updated since
2001 but some distros still seem to include it. The website at
http://www.opensourcepartners.nl/~costar/gramofile/ has some details of
the algorithms - including the ones that didn't work.
--
Dave

Finding clicks
 

On Sun, 07 Sep 2014 14:29:07 +0100, Jim Lesurf
wrote:


First, let me remind you of my own findings, which I've linked here
several time befo
http://www.macfh.co.uk/JavaJive/Audi...storation.html

Note particularly the section about using a binary chop method to
locate the clicks faster by eye, and the screen grabs combined with
audio examples showing the clicks being removed.

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!

Yes, no problem spotting these in the waveform, but not always easy to
fix - for example, some scratches in piping records cannot be just
interpolated, although this improves things significantly, often an
audible bump remains.

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.

Yes, my site contains a sample of several of these in a very short
section of music (it's actually Curved Air, for the afficionados), and
the clarity that results from fixing them all.

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.

I've tried many such programs, and basically none of them really work.
Either they miss too many genuine clicks and/or they mark too many
false positives, to be worthwhile.

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.

Yes, that sounds about right. Depending on condition, I used to
reckon about one or two sides could be done in an evening's work.

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...

My page describes the software that I was using. It's really quite
old now, but at the time was quite expensive.
--
================================================== =======
Please always reply to ng as the email in this post's
header does not exist. Or use a contact address at:
http://www.macfh.co.uk/JavaJive/JavaJive.html
http://www.macfh.co.uk/Macfarlane/Macfarlane.html

Finding clicks
 

On 07/09/2014 14:44, Don Pearce wrote:

The click fixer in CoolEdit (many incarnations, and there is a
shareware version among them) has a good reputation, and I've used it
successfully. The product was subsequently bought by Adobe and has
morphed into Audition - and become bloatware while abandoning the best
features.

The click filter in GoldWave works excellently.
It's not worth trying to do it by hand.
But it is worth doing a difference between the raw and declicked files,
which gives 20 minutes of silence and clicks that you can then add to
other music to give the authentic LP sound. :-)

--
Eiron.

Finding clicks
 

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. :-)


I can certainly vouch for that effect when such declicking tools are
used indiscriminately!

Like Don, I've been using CoolEdit. In my case the Pro version 1.0,
since before the turn of the century (from around 1997). I still use
it to this day but I've let the audio processing jobs stagnate these
last few years. :-(

CoolEdit Pro does have some fairly comprehensive click and pop
removal tools (and the usual noise elimination facilities as well, of
course!) but these do need to be applied with some care.

I suspect that there has been very little improvement over the past
17 years in this regard. One classic trap you can fall into is to use
automatic click removal over a whole track or even a whole LP's worth
when it contains brass wind instrumental sections since the
autodetection tends to treat this type of waveform as 'clicks'.
Indeed, this would make a nice test of the automated click removal.
Just select a section with brass (trumpets or whatever) and apply the
declicking process then compare the before and after. If you find the
processed audio is rather lacking power in the trumpet section, that
will just confirm the lack of progress I've surmised.

Like any complex tool, an audio editing program like CoolEdit, will
take some practice to get used to its limitations and to learn its
strengths (and features/foibles). I initially used it to control and
monitor the digitisation process whenever I transcribed vinyl and tape
recordings into standard wav files.

Using the older ISA soundcards (SB16, AWE64GOLD), the clip indicator
on CoolEdit's meter proved a very useful feature to let me see at a
glance whether any clipping had occurred whilst I'd had my back turned
and so alert me to the need to check and decide whether I'd have to
take another pass at a lower level (a very modest amount of real FSD
clipping was acceptable but in many cases, this could have simply been
the result of a loud pop or click in the source recording which, of
course would be excised before attempting to normalise the digital
capture).

Unfortunately, this neat clip indicator feature was defeated by the
initial crop of PCI soundcards[1] where the manufacturers it seemed,
all to a man, had slavishly followed the 'reference design' offered by
the sound chip maker and had managed to overlook the fact that
jumpering the 6dB sensitivity reduction option on the ADC had the
entirely foreseeable consequence of the input buffer amp clipping some
3dB below FSD due to reliance on the 5v line rather than a 10v
(derived from the 12v rail) source as I suspect was the case with the
older ISA cards. The aim of input noise reduction, whilst laudable
enough in its own right, unfortunately was a major error in the design
of these early PCI cards.

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).

Usually, at that point, I'd save the wav file for further processing
later as I deemed necessary (mostly a case of cleaning up the noise
during the quieter passages, most often, during the intertrack
pauses). This basic level of processing only took 5 to 10 minutes per
album's worth so that much seemed worth doing straight away before
moving onto the next album.

Generally, I'd digitise several LP's worth per session or, in the
case of the reel to reel recordings, either both sides of a 7 inch
reel of LP tape (96 minutes per side @3 3/4 ips) or else one side of a
10 inch reel, up to 3 1/4 hours' worth.

My aim was to archive the material into a state of digital
preservation that was cleaner than if it had been auditioned
directly. Even if I never got around to any further cleanup work,
they'd still be good enough for playback. I could try improving it any
time and, that is the problem with digital media, it can so easily
induce a tendency to "Mañana". :-\

[1] For many years, I felt I was in a wilderness of 'consumers blind
to this obvious deficit' / manufacturers who didn't give a flying
****. This deficit wasn't just limited to PCI soundcards alone, even
the on-board MoBo sound chips suffered this affliction.

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.
--
J B Good

Finding clicks
 

On Sun, 7 Sep 2014 14:47:44 +0100, Folderol
wrote:

On Sun, 07 Sep 2014 14:29:07 +0100
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...

Jim

Many years ago the BBC (I think) developed a system that worked by playing a
track *backwards*. The clicks still presented themselves as sharp edged
pulses, while the music was a slowly rising signal.

This echoes the method used to reduce the effects of group delay
inherent in the analogue magnetic recording process where they'd dub
the master onto a distribution copy tape with both machines running in
reverse.

It would make 'square waves' look like 'square waves' once more,
rather than triangle waves. However, since both sound
indistinguishable from each other, it was a moot point as to whether
this was worth doing just for its own sake. However, if you needed to
create disposable distribution copies and the machines could both run
in reverse, this would prevent piling up more such group delay
distortion, indeed, it reduced it even if the distortion wasn't
entirely cancelled out so no bad thing.
--
J B Good

Finding clicks
 

On Sun, 07 Sep 2014 16:40:06 +0100, Jim Lesurf
wrote:

I can illustrate the real challenge here with an example.

http://jcgl.orpheusweb.co.uk/temp/ZoomCircled.png

This shows the start of side 2 of an LP of Brahms 1st Piano Concerto
(Barbirolli, Barenboim on EMI 1967) Its a lovely LP but has various various
'ticks' that are clearly audible in the quiet passages.

The tick shown here at about 6.42 sec from the start is audible with the
piano. Note the low modulation levels. The music is below about -25dB as
recorded (0dBFS was about +17dBRIAA) and the tick is smaller in amplitude
than the music.

This one is relatively easy to find by ear-eye *but* you have to zoom the
time and amplitude scales to be able to see it. If you don't the ripple at
the bottom of the previous cycle looks like the cause because it sticks out
of the displayed waveform, but it isn't.

Other ticks are harder to find. But even this one seems a challenge to find
by an 'automated' locator.

Doing an automatic locator for loud bangs is easy. But then so is seeing
them with Audacity! Question is if this kind of example can be detected by
something of the kind I've mentioned. Ideally a program that generates a
list of 'click candidates' that would find this but not be swamped with
false positives. I suspect its almost impossible, but wonder what people
think.

IIRC (its been quite a while since I last did such processing), the
declick function in CoolEdit Pro lists the number of clicks and pops
it finds in a selection before allowing you to apply the removal
process itself.

If the click/pop count looks suspiciously on the high side you can
try the effect and audition it afterward (I've assumed you would have
already auditioned it beforehand). If there's no obvious improvement,
or worse still, a degradation, you can simply undo the action.

I do recall, however, that I tended to avoid auto repair and manually
deal with the quieter sections where such noise would be a real
intrusion (after dealing with the grosser, obvious by eye, clicks and
pops). Here, when the small selected portion was largely the same low
level amplitude, I found I could get away with using auto-declicking
in most cases. Any recalcitrant clicks that escaped their well
deserved fate I would home in on and manually edit the sound samples,
if need be.

Any other larger clicks hiding amongst the louder passages were
usually undetectable by ear. In any case, I figured this would be a
problem best left to my grandchildrens' progeny to solve. :-)

There's only so much you can do before the benefit to effort ratio
falls to a vanishingly small value where you begin to question your
very existence. Hell! If I was content to listen to this stuff (warts
and all) before, the result I've got so far aught to be more than
enough to improve my listening pleasure. Enough already! Just give it
a rest and be happy! \-)

If you mess around enough with such processing, you'll find out what
that last paragraph is all about soon enough.



Took me hours to do side 1! 8-] Its only something I'd do for 'special
cases' where I really want to clean up as much as possible particularly
enjoyable examples. ... and this is a 2 LP set. 8-]


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.

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.
--
J B Good