real time analysing frequence of audio input
in [Matlab]
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From: shab shekan on 14 Mar 2010 04:04 hello. I wrote a function for input audio from microphone,but i want when Frequence is lower or upper a constant frequence, stop the recording. the noise is not important, but accuracy is important.
From: Rune Allnor on 14 Mar 2010 05:57 On 14 Mar, 09:04, "shab shekan" <shabshekan_632...(a)yahoo.com> wrote: > hello. > I wrote a function for input audio from microphone,but i want when Frequence is lower or upper a constant frequence, stop the recording. > the noise is not important, but accuracy is important. Doing anything real-time in matlab is hard. It would take a lot of skills and effort to do what you want in real time. That being said, the task you indicate is a bit unconventional. You might want to use a recorded signal (e.g. a .wav file) and see if you can get the algorithm to work as you want, before you decide to spend all that effort n the real time part. That is, you split the .wav file into sections according to your stated criteria. Rune
From: Walter Roberson on 14 Mar 2010 12:52
shab shekan wrote: > I wrote a function for input audio from microphone,but i want when > Frequence is lower or upper a constant frequence, stop the recording. > the noise is not important, but accuracy is important. Ah, that code is easy in any digital recording system. In any digital recording system that _ever_ has a change in signal level, you *always* have frequencies present as high as you care to analyze. They are an unavoidable artifact of doing a fourier analysis on a system that implicitly models every sample as a square wave: remember that square waves and triangle waves in fourier systems contain infinite frequencies... Thus your code becomes simple: as you read in each sample, compare it to the previous sample. If it is different in even a single bit, then stop the recording. |