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Re: [ARSCLIST] Restoration of broken records...
see end...
----- Original Message -----
From: "Graham Newton" <gn@xxxxxxxxxxxxxxxxxxxxx>
Tom Fine wrote:
Finally had a chance to listen to both MP3 files. One man's opinion here,
but the de-thumping was too radical to my ears. It creates annoying gaps
in the music and makes the surface noise that's left pump so it's
actually more noticeable. Did you try a notch filter at the loudest
frequency of the thumps? I'd bet there's not much necessary music content
down that low in the bandwidth of a tight notch. That might make the
thumps less noticeable than the gaps and pumping are with the thumps
removed.
That said, it's pretty amazing you were able to paste that thing back
together and play it. The little ditty isn't half bad either.
As much as I hate to admit it, I've had CEDAR's de-thump and re-touch
processes for some years but problems with how the earlier SADiE hardware
and software platform handled things caused me to put it on the back
burner.
With the new SADiE v5 software and related hardware, the problems were
eliminated, and this example was my first effort at applying the processes
under these conditions. This was primarily for demonstrating the de-thump
process and yes, further improvements could definitely be made by applying
additional processes like CEDAR's NR-4.
Over that roughly 3 minute track, there were a little less than 200
individual de-thump edits and some were arguably better than others, but
on the whole, the result shows what can be done with severely damaged
source materials.
This process is manually intensive since it can't be automated and hence
is an expensive proposition that demands a decision on whether the rarity
of the source material justifies the cost of the work to be applied to it.
The example disc was one of a very few of these known to exist, so it was
justifiable, certainly as a test subject.
CEDAR's de-thump process, as I said, is manual and involves marking the
extent of the thump on the workstation oscillographic display, then
telling CEDAR how many cycles of thump exist in the marked area. De-thump
then looks at material on either side of the marked area and constructs
what it thinks would be the missing material in the marked area, and
substitutes that in the space. If the operator is wrong on the number of
thump cycles, it will affect what it substitutes to one degree or another,
and audibly to the critical listener.
All told however, the process is pretty remarkable and allows corrections
to be made without the timeline being affected.
And I reply from a position of effective ignorance...!
It would seem to me that there are two possible approaches here...?!
1) IF the record is "un-rare" enough that other copies are known to
exist...simply play an extant copy, open a "waveform" version of that
sound recording, play the broken and repaired copy, and substitute
segments of the "intact" waveform where "blanks" exist...!
2) IF the broken-and-repaired copy is the ONLY extant copy of
an extremely rare phonorecord...play that copy, open a "waveform
view" of the result, and manually "fill in the blanks"...with, if nothing
else, a straight line connecting both sides of the "gap"...?!
Is this, in fact, possible...?!
Steven C. Barr