[maxmsp] about mxj~ MSPBuffer poke method (and VBR mp3 lengths)

A long long long long long long time ago, Ali Momeni wanted to play  
with mp3's and mxj.

There http://www.synthesisters.com/hypermail/max-msp/Nov05/34373.html
He wrote :
"however, i'm having trouble setting the length of a buffer because  
the getFrameLength() method of an AudioInputStream seems to always  
return -1 (!@#$)."

And there were no answers. I wanted to give you the result of my  
searches about this specific subject:

1- Indeed, normal getFrameLength() does not give the length of an  
audiostream coming from an mp3. It exists a trick to calculate the  
mp3 length from the file information. However this is useless because  
you will anyway get problems with VBR mp3s...

2- It _seems_ (not 100% sure) the real trick is to use  
javazoom.jl.decoder.* ( http://www.javazoom.net/javalayer/ 
sources.html ) as follow :

import javazoom.jl.decoder.*;
...........

int nTotalMS = 0;

        try {
             Bitstream m_bitstream = new Bitstream(new FileInputStream 
(your_file));
             Header m_header = m_bitstream.readFrame();

             int mediaLength = (int)encodedFile.length();

             if (mediaLength != AudioSystem.NOT_SPECIFIED) {
                nTotalMS = Math.round(m_header.total_ms(mediaLength));
			}
             post("Length in ms: " + nTotalMS);
         } catch(Exception e) {
             e.printStackTrace();
	}
}


Best,
O./