Arun:
Bo's correct - this topic isn't specific to Qt.
However, just to get you started, I'll make several observations:
1. The best place to do audio noise reduction is when you capture your
original data. Use a more-directional microphone, use a secondary
microphone that is just capturing the "background noise" and subtract
that out from the primary microphone's signal, use wind screens
where necessary, etc.
2. Once you've captured your audio, of course that opportunity has
passed. At that point, most modern noise reduction is done in the
frequency domain rather than the time domain. The audio signal is
often run through a Fast Fourier Transform and converted into a
series of frequency bins. These content of these bins are then analyzed
and modified and the signal reconstructed by running it through an
Inverse Fourier Transform. In this process:
a. Constant background tones can be removed by zeroing
out their bin; that frequency will be missing in the output
but often won't be noticed by humans as missing.
b. Hiss can be removed by "thresholding" all bins downward
by a certain amount or by noticing, during silent periods, which
bins still contain signal and just thresholding down those bins.
c. The overall amplitude of the signal can be evaluated and all
bins can be clamped off when the signal is quiet.
Operating in the frequency domain, this can all produce better (sort-of
"self-interpolating") results than when you try to operate in the time domain.
This isn't meant to be a complete list but just something to start you
Googling.
Atlant
From: interest-bounces+aschmidt=dekaresearch....@qt-project.org
[mailto:interest-bounces+aschmidt=dekaresearch....@qt-project.org] On Behalf Of
Arun Kumar
Sent: Saturday, May 26, 2012 02:52
To: interest@qt-project.org
Subject: [Interest] Simple code to remove backgruund noise from audio sample
Hello,
I am developing one simple audio processing application in C++ using Qt.It can
record audio from microphone. When I play the recorded sound there is lots
background noise in it. Is there any simple code I can remove the background
noise from audio sample
I tried to replace zero to the below audio sound but the recording coming
through choppy and I searched in net for noise reduction methods found some
algorithms that all are very difficult to understand and implement in my code
Any code sample will very helpful to me
Many thanks,
Arun kumar
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