In article , RJH
wrote:
On 05/01/2017 09:39, Jim Lesurf wrote:

snip

FWIW I've recently been transferring and de-clicking some Ellington
'Radio Transcriptions' discs released on Decca London in the late
1970s.

Do you do it manually, in a sound file editor, and 'flatten the spikes'?
I've done that a few times, and the results are pretty good.

Or is there a decent software solution?

Mostly I use the 'repair' function that Audacity provides. This is limited
to a max of 128 samples per channel. But in effect it examines the patterns
either side of the selected series and attempts to do a smooth
interpolation of the shapes.

Since I record the LPs as 96k/24 that means it is limited to problems that
aren't longer than about 1.3-ish ms.

That works fine for me in most cases. The main exceptions are much longer
crunches or bangs, or clicks that leave a long LF 'tail'. For them I might
accept doing a snip. Although I suspect they might be easier to fix if the
digital recording was done without RIAA I've never bothered. The above
works fine in most cases. for me.

In practice I find I rarely need to snip out a section or use some other
means. The 'repair' generally produces a result where I can't hear any
problem once I've chosen the right start and end points.

The main 'trick' I use is to use sox to generate a high-pass filtered
version of a recording. Usually second order with a turnover around 5kHz. I
then load that into Audacity alongside the recording to be declicked. The
filtered version helps some smaller clicks to stand out, so they act as a
guide to 'find the Lady' if in the full recording the click is hiding in
the audio waveforms. It also shows more clearly the HF departures from a
smooth shape, so aids deciding the start and end points for an optimal
repair.

Caution: If you do the above make sure to take care *not* to save the
result in a way that adds back in the hf filtered version! 8-]

There are automated ways to do this. However I'm happy with the above, and
it also serves as an excuse to have a close listen to the recordings as I
'work on them'. :-) So it is usually fun and an interesting challenge
rather than a chore. No-one is paying me, I'm just doing it because I
prefer to.

Jim

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