Ale v té metodě se to vždy zavře.

public boolean decode(String inFileName, String outFileName) throws IOException {
        FileInputStream is = null;
        FileOutputStream os = null;
        try {
            is = new FileInputStream(inFileName);
            os = new FileOutputStream(outFileName);
            wav = new WavWriter(os);
            FLACDecoder decoder = new FLACDecoder(is);
            decoder.addPCMProcessor(this);
            decoder.decode();
        } catch (IOException e) {
             return false;
        } finally {
            if (is != null) {
                is.close();
            }
            if (os != null) {
                os.close();
            }
        }
        return true;
    }