海康摄像头获取视频帧数据可以通过NET_DVR_SetESRealPlayCallBack回调方法，视频帧默认为H.264帧，此帧能获取到音频和视频帧数据，回调方法如下：

音频和视频帧数据通过NET_DVR_PACKET_INFO_EX结构中的，dwPacketType属性进行判断

判断视频帧时仅需判断类型为1、2、3的帧即可，具体格式如下：

获取到H.264帧数据了，就需要对数据进行H.264解码，代码如下：

        unsafe void StrPacketInfo(int lPreviewHandle, ref NET_DVR_PACKET_INFO_EX packetinfo, uint dwUser)
        {
            if (packetinfo.dwPacketType == 1 || packetinfo.dwPacketType == 2 || packetinfo.dwPacketType == 3)
            {
                if (packetinfo.wWidth < 65535 && packetinfo.wHeight < 65535)
                {
                    int code = (int)packetinfo.dwPacketType;
                    int w = packetinfo.wWidth;
                    int h = packetinfo.wHeight;
                    FFDecoderAPI.FF_InitEx(0, w, h);
                    byte[] yuv = new byte[w * h * 3 / 2];
                    IntPtr yuvptr = Marshal.AllocHGlobal(yuv.Length);
                    FFDecoderAPI.FF_DecoderEx(0, packetinfo.pPacketBuffer, (int)packetinfo.dwPacketSize, yuvptr, w, h);
                    Marshal.Copy(yuvptr, yuv, 0, yuv.Length);
                    SetYuv(yuv, yuv.Length, w, h);
                    Marshal.FreeHGlobal(yuvptr);
                }
            }
            else if (packetinfo.dwPacketType == 10)
            {
                EasyVideoAPI.PushEasyFrame(packetinfo.pPacketBuffer, (int)packetinfo.dwPacketSize, false, false, Index);
            }
        }

这里用到了一个C++的H.264解码库：FFDecoder.lib

此类可以对H.264进行解码，解码输出为YUV420p格式为图像数据的拼接缩放等进行操作。

//=======================================================
//Decoder
#ifndef DECODER_H264
#define DECODER_H264			0x1C			//28
#endif
#ifndef DECODER_MPEG4
#define DECODER_MPEG4			0x0D			//13
#endif
#ifndef DECODER_MPEG2
#define DECODER_MPEG2			0x02			//2
#endif
#ifndef DECODER_MJPEG
#define DECODER_MJPEG			0x08			//8
#endif

#ifndef DECODER_MP3
#define DECODER_MP3				0x15001			//86017
#endif

#ifndef DECODER_AAC
#define DECODER_AAC				0x15002			//86018
#endif

//=======================================================
//输出格式
#ifndef OUTPUT_PIX_FMT_YUV420P
#define OUTPUT_PIX_FMT_YUV420P		0
#endif
#ifndef OUTPUT_PIX_FMT_YUYV422
#define OUTPUT_PIX_FMT_YUYV422		1
#endif
#ifndef OUTPUT_PIX_FMT_RGB565LE
#define OUTPUT_PIX_FMT_RGB565LE		44
#endif
#ifndef OUTPUT_PIX_FMT_RGBA
#define OUTPUT_PIX_FMT_RGBA			28
#endif

ManagerFFDecoder::ManagerFFDecoder()
{
	memset(ffDecoder, 0, sizeof(ffDecoder));
}

void ManagerFFDecoder::FF_Init(int _index, int _w, int _h)
{
	if (ffDecoder[_index] == NULL)
	{
		FFD_Init(&ffDecoder[_index]);
		int outfmt = OUTPUT_PIX_FMT_YUV420P;
		int incode = DECODER_H264;
		FFD_SetVideoDecoderParam(ffDecoder[_index], _w, _h, incode, outfmt);
	}
}

void ManagerFFDecoder::FF_Decoder(int _index, char* inbuf, int _bufsize, char* yuvbuf, int _w, int _h)
{
	if (ffDecoder[_index] != NULL)
		FFD_DecodeVideo3(ffDecoder[_index], inbuf, _bufsize, yuvbuf, _w, _h);
}

void ManagerFFDecoder::FF_Uinit(int _index)
{
	if (ffDecoder[_index] != NULL)
		FFD_Deinit(&ffDecoder[_index]);
}