@Override
    public float getDuration() {
        int bytesPerSec = (bitsPerSample / 8) * channels * sampleRate;
        if (audioData != null)
            return (float) audioData.limit() / bytesPerSec;
        else
            return Float.NaN; // unknown
    }
@return The duration of the audio in seconds. It is expected
that audio is uncompressed.
jme3-core/src/main/java/com/jme3/audio/AudioBuffer.java