luis jure <l...@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
