In article ,
Ian Jackson wrote:


I'm no expert, but I would have thought that you need a program which
would look at (say) 7kHz for clicks, and note the times when they
occurred. It would then replay and re-record the audio, using the timing
information to blank out the clicks from just before they occurred to
just after. A refinement would be to take a sample of the audio at just
before and just after a click, average it, and use it to fill in the
blanked-out bit. Is this the sort of thing that is done?

FWIW This morning I've been experimenting with the following lateral
thinking approach...

1) Use sox to generate a version which is highpass filtered e.g.

sox infile.wav outfile.wav highpass 5000

This creates a new file which has had a 2nd order highpass filter applied
with its turnover at 5kHz.

2) Load both the infile and the outfile versions into Audacity. So I can
see the top two tracks as the infile (orginal to be edited) and the bottom
two as the outfile (filtered to reduce the music and make clicks easier to
spot).

This seems to work fairly well and lets me see many clicks which otherwise
are hard to see in the original unless I already know where to look. So may
well be a useful way of quickly marking places to focus my attention upon.

What I'm not yet clear on is that I'm still learning about Audacity! So,
for example, I need to take care that I edit and save the original
*without* doing something daft like adding in the highpassed file when
exporting the results - thus putting the clicks back *and* adding a
shelved-up treble above 5kHz! 8-]

I *think* it is OK to 'solo' the infile I'm editing and 'mute' the filtered
one I'm using to see clicks more clearly. But I've only briefly exprimented
so far. Hence if anyone more used to Audacity can comment I'd be
interested.

Since the sox highpass is 2nd order it does approximate here to doing the
second differential on the portion of the signal below about 5kHz. I may
try a higher frequency for the filter to get closer to 2nd diff and/or
having sox apply some gain to keep the results big enough to easily see!

Slainte,

Jim

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