[MPlayer-dev-eng] Audio Visualization Plugin

[Gustavo Sverzut Barbieri]

I learned how to use fftw.

Now I need to know some things.

1) How do I call your plugins from mplayer command line? I tried -aop
list=delay, for example, but I got the libao2 plugin, not yours.

2) The data your interface will send to the plugin is the data I should
apply the Welch Periodogram? It's a matrix? What's its dimension? It
contains integers/doubles/longs?

I'm new to this digital signal process things. I didn't had time to
read those books yet, but I will. until that, could you help me a bit?

Before the Welch periodogram transform, what I have? And after the
transform, what I get? How I use it? 


Gustavo



 --- 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 have some sample code for using fftw if you want it (can't send it
> public so contact me outside list).
> 
> 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
> 
> 
> 

> ATTACHMENT part 2 application/octet-stream 
 

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