private boolean isSyncMark(int headerString, int syncMode, int word) {
        boolean sync = false;
        if (syncMode == INITIAL_SYNC) {
            sync = ((headerString & 0xFFE00000) == 0xFFE00000); // SZD: MPEG 2.5
        } else {
            sync = ((headerString & 0xFFF80C00) == word) && (((headerString & 0x000000C0) == 0x000000C0) == singleChMode);
        }
        // filter out invalid sample rate
        if (sync) {
            sync = (((headerString >>> 10) & 3) != 3);
        }
        // filter out invalid layer
        if (sync) {
            sync = (((headerString >>> 17) & 3) != 0);
        }
        // filter out invalid version
        if (sync) {
            sync = (((headerString >>> 19) & 3) != 1);
        }
        return sync;
    }