Re: [LAU] Improving a bad recording

Excerpts from Kevin Cosgrove's message of 2010-06-02 01:59:30 +0200:
>
> On 2 June 2010 at 0:10, Philipp <hollunder@lavabit.com> wrote:
>
> > It would be nice if I could at least improve the recording, but
> > I don't quite know how to start. My only 'source' file is a
> > single mp3.
>
> Bummer. But, ya can still learn.
>
> > The major problems of the recording are: 1) quite a lot too
> > much bass of the acoustic guitar - this is easy to correct
> >
> > 2) a very loud noise, possibly from some part of a laptop. To
> > my knowledge the recording was made in two takes, guitar and
> > voice, on a laptop with a cheap mic of some sort. The noise
> > seems to be located mainly somewhere around 12kHz, a region
> > which seems to be important for the clarity of the voice. Any
> > attempts to just pull down with an eq (4-band parametric for
> > example is what I tried today) had a significant impact on the
> > voice.
> >
> > 3) a constant level of noise, probably from some part of the
> > cheap equipment used. Due to the two takes it's 'doubled' for
> > the most part of the song.
>
> Is there any part of the sound file that has only the noise
> present, without the music playing? The more the better; 5-10
> seconds would be good, and 1-2 seconds might be adequate. If
> so, then you could try the noise removal effect in Audacity.
> I use it often and I'm quite happy with it. I would try the
> noise removal first, before compounding the recording with other
> effects.
 
Thanks for your reply Kevin. Audacity and its noise removal facilities
was the first thing I tried, about 7 years ago, back then on windows. I
may have tried it another time in between. Maybe it's time to give it
another shot.

> Audacity at version 1.3.11 (probably before then, but certainly
> after 1.3.0) has a good graphic equalizer in it.
>
> Parametric EQ might help to really "zoom in" on some things.
>
> > To tip it all off, I can't even make out all lyrics. It might
> > be that some significant hints are simply masked by the noise,
> > or they simply are hard to make out.
>
> After the noise reduction, then you might try compression or
> expansion to isolate various sounds. Frequency sensitive
> compression or expansion might also help, but is more difficult
> to use.

I've seen some calf sideband compressor, maybe it will help with that,
thanks for the idea.

> > I'd really love to somehow get this recording to an enjoyable
> > state, no matter how involving it is. Given the source it seems
> > next to impossible, but it has to be possible to make at least
> > some improvements.
>
> One thing you might try, which I haven't tried, is to make
> several passes at the file. On each pass you try to isolate one
> instrument or vocal, making that sound as good as you can, while
> trying to eliminate all the other sounds. Saving a collection
> of those kinds of sound files might allow you to mix those
> intermediate files back together to produce something useful.

This is certainly a thing worth trying, thanks. I'm not sure thought
that I can isolate it well enough to make this work.

> Is this recording stereo, with things panned somewhat left and
> other things panned somewhat right, and yet other things panned
> to center? If so, then you might be able to get at yet more
> aspects of the recording by subtracting right from left, or visa
> versa.

From what I gathered today the mp3 is stereo, but it was recorded in two
passes with a single mic afaik, and I'm reasonably sure that there's no
panning whatsoever. I'll check, but I think there's nothing to be
gained in this way.

> Hmm, you might also websearch for "audio forensics" or "audio
> restoration" or similar topics as I'm sure there are folks who've
> been farther down this path.

Thanks for the search hints.

> Please report back on how it goes. I'll look for your report in 7
> years. ;-)
>
> Good luck!

I hope it won't take another 7 years, but who knows...

-- 
Regards,
Philipp
--
"Wir stehen selbst enttäuscht und sehn betroffen / Den Vorhang zu und alle Fragen offen." Bertolt Brecht, Der gute Mensch von Sezuan
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