Re: [gentoo-user] [OT]: Denoising software ?

[meino.cramer@gmx.de]

luis jure <ljc@internet.com.uy> [11-12-10 13:28]:
> on 2011-12-09 at 13:55 Michael Mol wrote:
> 
> >I couldn't tell you if it's necessarily "good", but Audacity has a
> >noise filter.
> 
> that's exactly what i was about to reply.
> 
> and if you want to try a CLI tool, sox provides a similar utility.
> 
> noiseprof [profile-file]
>         Calculate  a  profile  of the audio for use in noise reduction.
>         See the description of the noisered effect for details.
> 
> noisered [profile-file [amount]]
>        Reduce noise in the audio signal by profiling and filtering.  This
>        effect is moderately effective at removing consistent background
>        noise such as hiss or hum.  To use it, first run SoX with the
>        noise‐ prof effect on a section of audio that ideally would contain
>        silence but in fact  contains  noise  - such sections are typically
>        found at the beginning or the end of a recording.  noiseprof will
>        write out a noise profile to profile-file, or to stdout if no
>        profile-file or if `-' is given. E.g. sox speech.wav -n trim 0 1.5
>        noiseprof speech.noise-profile To actually remove the noise, run
>        SoX again, this time  with  the noisered  effect;  noisered  will
>        reduce  noise according to a noise profile (which was generated by
>        noiseprof), from profile-file, or from stdin if no profile-file or
>        if `-' is given. E.g. sox speech.wav cleaned.wav noisered
>        speech.noise-profile 0.3 How much noise should be removed is
>        specified by amount-a number between 0 and 1 with a  default  of
>        0.5.  Higher numbers will remove more noise but present a greater
>        likelihood of removing wanted components of the audio signal.
>        Before replacing an original recording with a  noise-reduced
>        version, experiment with  different  amount values to find the
>        optimal one for your audio; use headphones to check that you are
>        happy with the results, paying particular attention to quieter
>        sections  of  the audio.
> 
>        On most systems, the two stages - profiling and reduction
>        - can be combined using a pipe, e.g. sox noisy.wav -n
>        trim 0 1 noiseprof | play noisy.wav noisered
> 
> never compared the results, if you do, i for one would be very interested
> in your experience. 
> 
> IMO, it's much better to remove noise by small amounts in successive
> passes (taking a new profile each time, of course), than trying to remove
> too much noise in one pass.
> 
> let us know how it went!
> 
> lj
> 

Thanks for all your replies ! :)


In the net I read about audacities denoise and that it is not /that/
good. I didnt checked it myself though.  At the same place "Gnome Wave
Cleaner" (gwc) was recommended instead of audacities denoiser. On its
homepage there is also linked a downloadable book about digital signal
processing (34 chapters) which looks quite proefessional.

Gwc is ... not the youngest software and development seems to have
stopped. Now I trying to get this beast working under Gentoo.
The alsa-problem with "snd_pcm_write" can be workarounded ;) with
installing pulseaudio and playing the sound with gwc via pulseaudio
instead of with alsa directly.
While compiling gwc you need to enable alsa and pulseaudio with
./configure.

When gwc is running I wll report more.
See my other posting sent just before this one.

Gwc is the first denoise I will try.

Have a nice, denoised  weekend! :)
Best regards,
mcc