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

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

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.

You will need to adopt the dreaded windows to use it, I'm afraid.

d

In article , Don Pearce
wrote:
On Sun, 07 Sep 2014 14:29:07 +0100, Jim Lesurf
wrote:
[snip]


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.

Does it *find* the clicks automatically? Fixing them is easy.

You will need to adopt the dreaded windows to use it, I'm afraid.

It would be easier to experiment with making use of the approach for
auto-finding clicks if the above has one, and use my own software.

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

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

In article , Don Pearce
wrote:
On Sun, 07 Sep 2014 14:29:07 +0100, Jim Lesurf
wrote:
[snip]


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.

Does it *find* the clicks automatically? Fixing them is easy.

You will need to adopt the dreaded windows to use it, I'm afraid.

It would be easier to experiment with making use of the approach for
auto-finding clicks if the above has one, and use my own software.

Jim

It has several modes. There's full auto where you just let it loose, a
directed one where you can set thresholds and a manual one where you
find the clicks, surround them with a pair of cursors, and some
algorithm - spline or whatever - connects the two ends together.

d

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

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

In article , Don Pearce
wrote:
On Sun, 07 Sep 2014 14:29:07 +0100, Jim Lesurf
wrote:
[snip]


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.

Does it *find* the clicks automatically? Fixing them is easy.

You will need to adopt the dreaded windows to use it, I'm afraid.

It would be easier to experiment with making use of the approach for
auto-finding clicks if the above has one, and use my own software.

Jim

It has several modes. There's full auto where you just let it loose, a
directed one where you can set thresholds and a manual one where you
find the clicks, surround them with a pair of cursors, and some
algorithm - spline or whatever - connects the two ends together.

d


Jim, I don't know if you can watch Youtube, but here's a short clip on
the manual repair process. It's actually Audition, but they haven't
changed this bit, so it still applies

https://www.youtube.com/watch?v=ohbulIv1rUM

d

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

In article ,
Don Pearce wrote:

You will need to adopt the dreaded windows to use it, I'm afraid.

Or grab a glass of WINE!

I still run CoolEdit Pro 2.1 under WINE on Slackware, the last version
from before Adobe stuck their bib in.

--
--------------------------------------+------------------------------------
Mike Brown: mjb[-at-]signal11.org.uk | http://www.signal11.org.uk

--- news://freenews.netfront.net/ - complaints: ---

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.

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.


--
W J G

In article 20140907144744.351a420b@debian,
Folderol wrote:
On Sun, 07 Sep 2014 14:29:07 +0100
Jim Lesurf wrote:
[snip]

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.

In effect, that's what I'm experimenting with at present.

My first experiments scan though looking at the level. Then finding places
where the peak levels drop a great deal in a short time. Thus picking up
events with a sharply falling trailing edge. I've tried combining this with
the peak level and crest factors.

It works for the most obvious clicks. But not for the small ones whose size
is *not* much bigger than the musical waveforms. So it shows clicks that
are also clear to see with Audacity, but misses the smaller hard-to-see
examples. So it is useful, but limited in value.

Hence I'm thinking of trying the same approach as above, but to the first
or second differential of the waveforms to change the relative scaling of
quick events (with a lot of HF) to the surrounding music.

BTW I also recall the old Hi Fi News cover showing some LP replay systems
at their pressing factory. These looked strange because they were playing
the LPs 'backward'. They were being used to look for faults (clicks) so
went backwards for the same reason as above.

Anyone buying EMI classical LPs at the time may not have been astonished
that 2 out of 3 of the decks shown had a big red 'fault detected' light lit
up. 8-] That seemed about right to me at the time. About 2/3rds of the EMI
classical LPs I bought then had to be returned due to the added rifle
shots!

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