C++获取网络相机rtsp视频流并使用opencv播放

首先先创建项目，ctrl+alt+t打开终端

mkdir ffmpeg_demo
cd ffmpeg_demo
vim test.cpp

在test.cpp中输入以下代码

/*opencv库*/
#include 
#include 
extern "C"   /*这里必须要使用C方式导入*/
{
#include "libavcodec/avcodec.h"
#include "libavdevice/avdevice.h"
#include "libavformat/avformat.h"
#include "libavfilter/avfilter.h"
#include "libavutil/avutil.h"
#include "libavutil/time.h"
#include "libswscale/swscale.h"
#include "libavutil/pixdesc.h"
}
 
#pragma comment(lib, "avformat.lib")
#pragma comment(lib, "avdevice.lib")
#pragma comment(lib, "avcodec.lib")
#pragma comment(lib, "avutil.lib")
#pragma comment(lib, "avfilter.lib")
#pragma comment(lib, "swscale.lib")
#pragma comment(lib, "swresample.lib")
#pragma comment(lib, "postproc.lib")
 
using namespace std;
using namespace cv;
 
void open_rtsp(const char *rtsp)
{
	unsigned int    i;
	int             ret;
	int             video_st_index = -1;
	int             audio_st_index = -1;
	AVFormatContext *ifmt_ctx = NULL;
	AVPacket        pkt;
	AVStream        *st = NULL;
	char            errbuf[64];
	AVDictionary *optionsDict = NULL;
	av_register_all();                                                          // Register all codecs and formats so that they can be used.
	avformat_network_init();                                                    // Initialization of network components
	av_dict_set(&optionsDict, "rtsp_transport", "tcp", 0);                //采用tcp传输	,,如果不设置这个有些rtsp流就会卡着
	av_dict_set(&optionsDict, "stimeout", "2000000", 0);                  //如果没有设置stimeout
 
	av_init_packet(&pkt);                                                       // initialize packet.
	pkt.data = NULL;
	pkt.size = 0;
	bool nRestart = false;
	AVStream *pVst;
	uint8_t* buffer_rgb = NULL;
	AVCodecContext *pVideoCodecCtx = NULL;
	AVFrame         *pFrame = av_frame_alloc();
	AVFrame         *pFrameRGB = av_frame_alloc();
	int got_picture;
	SwsContext      *img_convert_ctx = NULL;
	AVCodec *pVideoCodec = NULL;
 
	if ((ret = avformat_open_input(&ifmt_ctx, rtsp, 0, &optionsDict)) < 0) {            // Open the input file for reading.
		printf("Could not open input file '%s' (error '%s')\n", rtsp, av_make_error_string(errbuf, sizeof(errbuf), ret));
		goto EXIT;
	}
 
	if ((ret = avformat_find_stream_info(ifmt_ctx, NULL)) < 0) {                // Get information on the input file (number of streams etc.).
		printf("Could not open find stream info (error '%s')\n", av_make_error_string(errbuf, sizeof(errbuf), ret));
		goto EXIT;
	}
 
	for (i = 0; i < ifmt_ctx->nb_streams; i++) {                                // dump information
		av_dump_format(ifmt_ctx, i, rtsp, 0);
	}
 
	for (i = 0; i < ifmt_ctx->nb_streams; i++) {                                // find video stream index
		st = ifmt_ctx->streams[i];
		switch (st->codec->codec_type) {
		case AVMEDIA_TYPE_AUDIO: audio_st_index = i; break;
		case AVMEDIA_TYPE_VIDEO: video_st_index = i; break;
		default: break;
		}
	}
	if (-1 == video_st_index) {
		printf("No H.264 video stream in the input file\n");
		goto EXIT;
	}
	while (1)
	{
		do {
			ret = av_read_frame(ifmt_ctx, &pkt);                                // read frames
#if 1
			cout << pkt.size << endl;
			//decode stream
			if (!nRestart)
			{
				pVst = ifmt_ctx->streams[video_st_index];
				pVideoCodecCtx = pVst->codec;
				pVideoCodec = avcodec_find_decoder(pVideoCodecCtx->codec_id);
				if (pVideoCodec == NULL)
					return;
				//pVideoCodecCtx = avcodec_alloc_context3(pVideoCodec);
 
				if (avcodec_open2(pVideoCodecCtx, pVideoCodec, NULL) < 0)
					return;
                nRestart = true;
			}
 
			if (pkt.stream_index == video_st_index)
			{
				fprintf(stdout, "pkt.size=%d,pkt.pts=%lld, pkt.data=0x%x.", pkt.size, pkt.pts, (unsigned int)pkt.data);
				int av_result = avcodec_decode_video2(pVideoCodecCtx, pFrame, &got_picture, &pkt);
 
				if (got_picture)
				{
					fprintf(stdout, "decode one video frame!\n");
				}
 
				if (av_result < 0)
				{
					fprintf(stderr, "decode failed: inputbuf = 0x%x , input_framesize = %d\n", pkt.data, pkt.size);
					return;
				}
#if 1
				if (got_picture)
				{
					int bytes = avpicture_get_size(AV_PIX_FMT_RGB24, pVideoCodecCtx->width, pVideoCodecCtx->height);
					buffer_rgb = (uint8_t *)av_malloc(bytes);
					avpicture_fill((AVPicture *)pFrameRGB, buffer_rgb, AV_PIX_FMT_RGB24, pVideoCodecCtx->width, pVideoCodecCtx->height);
 
					img_convert_ctx = sws_getContext(pVideoCodecCtx->width, pVideoCodecCtx->height, pVideoCodecCtx->pix_fmt,
						pVideoCodecCtx->width, pVideoCodecCtx->height, AV_PIX_FMT_BGR24, SWS_FAST_BILINEAR, NULL, NULL, NULL);
					if (img_convert_ctx == NULL)
					{
 
						printf("can't init convert context!\n");
						return;
					}
					sws_scale(img_convert_ctx, pFrame->data, pFrame->linesize, 0, pVideoCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);
					IplImage *pRgbImg = cvCreateImage(cvSize(pVideoCodecCtx->width, pVideoCodecCtx->height), 8, 3);
					memcpy(pRgbImg->imageData, buffer_rgb, pVideoCodecCtx->width * 3 * pVideoCodecCtx->height);
					//Mat Img = cvarrToMat(pRgbImg, true);
					cvShowImage("GB28181Show", pRgbImg);
					//DetectFace(Img);
					cvWaitKey(10);
					cvReleaseImage(&pRgbImg);
					sws_freeContext(img_convert_ctx);
					av_free(buffer_rgb);
				}
#endif
			}
 
#endif
		} while (ret == AVERROR(EAGAIN));
 
		if (ret < 0) {
			printf("Could not read frame ---(error '%s')\n", av_make_error_string(errbuf, sizeof(errbuf), ret));
			goto EXIT;
		}
 
		if (pkt.stream_index == video_st_index) {                               // video frame
			printf("Video Packet size = %d\n", pkt.size);
		}
		else if (pkt.stream_index == audio_st_index) {                         // audio frame
			printf("Audio Packet size = %d\n", pkt.size);
		}
		else {
			printf("Unknow Packet size = %d\n", pkt.size);
		}
		av_packet_unref(&pkt);
	}
 
EXIT:
 
	if (NULL != ifmt_ctx) {
		avformat_close_input(&ifmt_ctx);
		ifmt_ctx = NULL;
	}
 
	return;
}
 
int main(int argc, char* argv[])
{
while(1)
open_rtsp("rtsp://192.168.1.86");
return 0;
}

保存代码后，使用g++直接编译

g++ test.cpp -std=c++11 -L/usr/local/lib -lpostproc -lswresample -lswscale -lavfilter -lavutil -lavcodec -lavdevice -lavformat -lopencv_core -lopencv_highgui -lswscale -o test

得到可执行文件test

./test

即可得到画面

可通过ctrl+c来终止程序运行