class RtpHeader implements Serializable {

    protected int append(byte[] data, int offset, int len) {
        int remainder = Math.min(12 - pos, len);
        System.arraycopy(data, offset, bin, pos, remainder);
        pos += remainder;
        if (pos == 12) {
            init(bin);
            filled = true;
        }
        return len - remainder;
    }

}