[MPlayer-dev-eng] Audio Visualization Plugin
Gustavo Sverzut Barbieri
gsbarbieri at yahoo.com.br
Fri Aug 30 18:25:47 CEST 2002
--- Anders Johansson <ajh at atcrc.com> escreveu:
> Hi Gustavo,
>
> The current audio plugin layer will soon be replaced by a new more
> generic one. Attached to this mail is the current work in progress.
> Warning the attached files "mplayer.c" and "Makefile" brakes mplayer
> a
> little bit so take appropriate precautions before you use them.
>
> As for where to start:
>
> If you want to do something that works for real (which imho you
> should) then you could use Welch periodogram method to do the
> spectral estimation. This will give you a good spectral estimates
> where the level of each frequency bin represents the actual energy
> level in that frequency band.
>
> To do the required FFT you could use the fftw package (very fast).
>
> If you have access to Matlab (and understands matlab code) you could
> have a look at the source code for the psd() function to get the
> implementation started (search for psd.m in the matlab installation
> directory to find it). I guess you can find something similar in
> Octave. I can also recommend the following two books on the subject:
>
> "Digital spectral analysis with application", S.Lawrence Marple, Jr
> "Statistical Digital Signal Processing and Modeling", Monson H. Hayes
>
I'll try to find them here in my university.
> I have some sample code for using fftw if you want it (can't send it
> public so contact me outside list).
>
Please, send me: gsbarbieri at yahoo.com.br
> To check your results try dumping the estimates to file and read them
> with gnuplot or matlab.
>
> I will be happy to help you with the audio part of the work.
>
> Good luck,
> //Anders
I'll start looking the Welch Method, then I'll try to implement it. If
I succeed, I'll try to integrate with your new libaf
Thanks for your help! :)
Gustavo
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