c++实现ffmpeg获取rtsp视频流，并使用opencv显示图像

要实现这个功能，首先需要安装FFmpeg和OpenCV库。然后可以按照以下步骤进行操作：

1. 导入头文件

#include <iostream>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/videoio.hpp>
#include "ffmpeg.h"

2. 定义回调函数

void display_frame(cv::Mat frame)
{
    cv::imshow("Video", frame);
    cv::waitKey(1);
}

3. 定义获取视频流的函数

void get_stream(const std::string& url)
{
    AVFormatContext* format_ctx = avformat_alloc_context();
    AVDictionary* options_dict = NULL;
    av_dict_set(&options_dict, "rtsp_transport", "tcp", 0);
    av_dict_set(&options_dict, "stimeout", "5000000", 0);
    av_dict_set(&options_dict, "max_delay", "500000", 0);
    av_dict_set(&options_dict, "buffer_size", "1024000", 0);
    av_dict_set(&options_dict, "rtbufsize", "1024000", 0);
    av_dict_set(&options_dict, "max_delay", "500000", 0);
    avformat_open_input(&format_ctx, url.c_str(), NULL, &options_dict);
    avformat_find_stream_info(format_ctx, NULL);
    AVCodec* codec = nullptr;
    int stream_index = av_find_best_stream(format_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &codec, 0);
    AVCodecContext* codec_ctx = avcodec_alloc_context3(codec);
    avcodec_parameters_to_context(codec_ctx, format_ctx->streams[stream_index]->codecpar);
    avcodec_open2(codec_ctx, codec, NULL);
    AVPacket* packet = av_packet_alloc();
    AVFrame* frame = av_frame_alloc();
    while (av_read_frame(format_ctx, packet) >= 0) {
        if (packet->stream_index == stream_index) {
            avcodec_send_packet(codec_ctx, packet);
            while (avcodec_receive_frame(codec_ctx, frame) == 0) {
                cv::Mat mat(frame->height, frame->width, CV_8UC3, frame->data[0]);
                cv::cvtColor(mat, mat, cv::COLOR_BGR2RGB);
                display_frame(mat);
                av_frame_unref(frame);
            }
        }
        av_packet_unref(packet);
    }
    av_packet_free(&packet);
    av_frame_free(&frame);
    avcodec_close(codec_ctx);
    avcodec_free_context(&codec_ctx);
    avformat_close_input(&format_ctx);
}

4. 调用函数播放视频流

int main()
{
    std::string url = "rtsp://xxx.xxx.xxx.xxx:xxxx/xxx";
    get_stream(url);
    return 0;
}

这样就可以获取RTSP视频流并使用OpenCV显示图像了。