[Qt-interest] Frequency of Audio Tracks

[Sean Harmer]

Hi,

On 24/07/2010 18:29, Vijay Kansal wrote:
> Hi,
> I want to develop an audio editor using Qt.
> For this, I need to plot a waveform of the music track which I
> think should be a plot of frequency of sound versus time(please correct
> me if I am wrong).
> Currently, I have been using Phonon::AudioOutput class object as an
> audio sink and connected it with my Phonon::MediaObject class object to
> play the audio file.
> Now, to draw the waveform I need to know the frequeny of audio track at
> every second (,or so) from this AudioOutput object so that I can draw a
> line (using QPainter) of length proportional to sound frequency at
> different times and hence, obtain my waveform.
> So, please help me on how to obtain frequency of audio tracks at
> different times.

Please read my response to your previous thread on the same topic and 
the link contained therein. In the linked blog entry pay particular 
attention to the section about fast fourier transforms (FFT).

Sean