final ArrayList<SilenceInfo> silence = new ArrayList<SilenceInfo>();

ProcessBuilder n = new ProcessBuilder();

// just run silence detect to null
List<String> meta = new ArrayList<String>();
meta.add("ffmpeg");
meta.add("-i");
meta.add("PATH/TO/MP3");
meta.add("-af");
meta.add("silencedetect=n=-50dB:d=1");
meta.add("-f");
meta.add("null");
meta.add("-");
n.command(meta);

// TODO: run it, parse the lines and add the SilenceInfos to silence!

// we got the silence now!
double firstSilenceEnd = 0, lastSilenceStart = 0;

boolean cutStart = false, cutEnd = false;

// no silence at all
if(silence.size() == 0) {
    // skip
} else if(silence.size() == 1) {
    // has to be at the end because no end was given
    lastSilenceStart = silence.get(0).getTimeStart();
    cutEnd = true;
} else {
    // silence at all ends
    for(SilenceInfo s : silence) {
        if(firstSilenceEnd == 0 && s.getTimeEnd() != -1)
            firstSilenceEnd = s.getTimeEnd();

        if(s.getTimeStart() != -1)
            lastSilenceStart = s.getTimeStart();
    }
    cutStart = true;
    cutEnd = true;
}

n = new ProcessBuilder();

meta = new ArrayList<String>();
meta.add("ffmpeg");
meta.add("-i");
meta.add("PATH/TO/MP3);
if(cutStart) {
    meta.add("-ss");
    meta.add(firstSilenceEnd + "");
}
if(cutEnd) {
    meta.add("-t");
    meta.add((lastSilenceStart - firstSilenceEnd) + "");
}
meta.add("-y");
meta.add("-ab");
meta.add("AUDIO BIRATE EG 192k");
meta.add("PATH/TO/TARGET");
n.command(meta);

// TODO: run it