ffmpeg opencv 打开视频文件，并且播放

// FFMpeg + OpenCV demo  
#include   
#include   
#include   

#ifdef __cplusplus  
extern "C" {
#endif  

#include   
#include   
#include   
#include   
#include   
#include   
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#ifdef __cplusplus  
}
#endif  

#include 

static void CopyDate(AVFrame *pFrame, int width, int height, int time);
static void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame);

using namespace cv;
using namespace std;

int main(int argc, char* argv[])
{
	int result = 0;
	av_register_all(); // 注册所有FFmpeg库所支持的文件格式和codec

	AVFormatContext* pFormatCtx;
	char* filename = "up.mp4"; //输入文件名

	// step1: 打开媒体文件,最后2个参数是用来指定文件格式，buffer大小和格式参数，设置成NULL的话，libavformat库会自动去探测它们
	result = avformat_open_input(&pFormatCtx, filename, NULL, NULL);
	if (result != 0)
	{
		cout << "open file fail" << endl;
		return -1;
	}
	cout << "open file succ" << endl;

	// step2: 查找信息流的信息
	result = avformat_find_stream_info(pFormatCtx, NULL);
	if (result != 0)
	{
		cout << "find stream fail" << endl;
		return -1;
	}
	cout << "find stream succ" << endl;

	// step3: 打印信息
	//av_dump_format(pFormatCtx, 0, filename, 0);

	// step4：找到video流数据
	int i = 0;
	int videoStream = -1;
	AVCodecContext* pCodecCtx = NULL;
	for (i = 0; i < pFormatCtx->nb_streams; i++)
	{
		if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
		{
			videoStream = i;
			break;
		}
	}

	if (videoStream == -1)
	{
		cout << "find stream video fail" << endl;
		return -1;
	}
	cout << "find stream video succ." << endl;

	// 得到video编码格式
	pCodecCtx = pFormatCtx->streams[videoStream]->codec;
	
	// step5: 得到解码器
	AVCodec* pCodec = NULL;
	pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
	if (pCodec == NULL)
	{
		cout << "find decoder fail" << endl;
		return -1;
	}
	cout << "find decoder succ" << endl;

	result = avcodec_open2(pCodecCtx, pCodec, NULL);
	if (result != 0)
	{
		cout << "open codec fail" << endl;
		return -1;
	}
	cout << "open codec succ" << endl;

	// step6: 申请原始数据帧 和 RGB帧内存
	AVFrame* pFrame = NULL;
	AVFrame* pFrameRGB = NULL;
	pFrame = av_frame_alloc();
	pFrameRGB = av_frame_alloc();
	if (pFrame == NULL || pFrameRGB == NULL)
	{
		return -1;
	}

	int numBytes = avpicture_get_size(AV_PIX_FMT_RGB24, pCodecCtx->width, pCodecCtx->height);
	uint8_t* buffer = (uint8_t*)av_malloc(numBytes * sizeof(uint8_t));
	avpicture_fill((AVPicture*)pFrameRGB, buffer, AV_PIX_FMT_RGB24, pCodecCtx->width, pCodecCtx->height);

	int frameFinishsed = 0;
	AVPacket packet;
	i = 0; 

	// step7: 创建格式转化文本
	SwsContext * pSwxCtx = sws_getContext(
		pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,
		pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_RGB24,
		SWS_BILINEAR, 0, 0, 0);

	cv::Mat image(pCodecCtx->height, pCodecCtx->width, CV_8UC3);
	int b = 0;
	int g = 1;
	int r = 2;

	while (true)
	{
		// 得到数据包
		result = av_read_frame(pFormatCtx, &packet);
		if (result != 0)
		{
			break;
		}

		if (packet.stream_index == videoStream)
		{
			// 解码
			avcodec_decode_video2(pCodecCtx, pFrame, &frameFinishsed, &packet);

			if (frameFinishsed)
			{
				// 转换
				sws_scale(pSwxCtx, pFrame->data, pFrame->linesize, 0, pCodecCtx->height,
					pFrameRGB->data, pFrameRGB->linesize);

				for (int m = 0; m < pCodecCtx->height; m++)
				{
					for (int n = 0; n < pCodecCtx->width; n++)
					{
						image.at(m, n)[r] = pFrameRGB->data[0][3 * (m*pCodecCtx->width + n) + 0];
						image.at(m, n)[g] = pFrameRGB->data[0][3 * (m*pCodecCtx->width + n) + 1];
						image.at(m, n)[b] = pFrameRGB->data[0][3 * (m*pCodecCtx->width + n) + 2];
					}
				}
				cv::imshow("pic", image);
				cv::waitKey(30);
			}
		}

		av_free_packet(&packet);
	}
	
	avformat_close_input(&pFormatCtx);

	system("pause");
	return 0;
}