关于Java中位运算，请高手解释一下这个问题

    private int sequenceNum;
    private byte[] audioData;
    public static final int MIN_HEAD = 12;    public RtpPacket(byte[] srcData) throws IOException
    {
        int iPlayDataIndx = MIN_HEAD;
        int cc = srcData[0] & 0x0F;
        iPlayDataIndx += cc * 4;
        sequenceNum = srcData[2] * 0x100 | (srcData[3] & 0xFF);
        int x = srcData[0] & 0x10;
        if (1 == x)
        //有拓展头
        {
            int headerExtensionLength = srcData[iPlayDataIndx + 2] * 0x100
                    | (srcData[iPlayDataIndx + 3] & 0xFF);
            iPlayDataIndx += 4;
            iPlayDataIndx += headerExtensionLength;
        }
        audioData = new byte[srcData.length - iPlayDataIndx];
        System
                .arraycopy(srcData, iPlayDataIndx, audioData, 0,
                        audioData.length);
    }
这个是对RTP包数据解析的一个过程，
请教一下其中        int cc = srcData[0] & 0x0F;
sequenceNum = srcData[2] * 0x100 | (srcData[3] & 0xFF);
        int x = srcData[0] & 0x10;
            int headerExtensionLength = srcData[iPlayDataIndx + 2] * 0x100
                    | (srcData[iPlayDataIndx + 3] & 0xFF);
这些位运算是什么意思？小弟对位运算不是很通，请高手指点一下