效果 🔅

Clion 中演示的效果

Clion 调试效果图

终端中运行也没有问题

终端中运行效果图

思路 💡

通过 fork 一个子进程来调用 ffmpeg 进行推流,视频帧通过 opencv 来获取,通过管道传输到子进程,实现推流

代码 🔨

需要注意的是,机器上要先安装 ffmpeg,其次视频的帧率一定要匹配,否则会出现莫名其妙的问题

main.cc:

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#include <iostream>
#include <csignal>
#include <opencv4/opencv2/opencv.hpp>

bool is_running = true;

void OnSignal(int) {
is_running = false;
}

int main() {
// 触发下面的信号就退出
signal(SIGINT, OnSignal);
signal(SIGQUIT, OnSignal);
signal(SIGTERM, OnSignal);

// 打开摄像头
cv::VideoCapture capture(0);
if (!capture.isOpened()) {
std::cerr << "Failed to open camera." << std::endl;
return EXIT_FAILURE;
}
capture.set(cv::CAP_PROP_FRAME_WIDTH, 1280);
capture.set(cv::CAP_PROP_FRAME_HEIGHT, 720);

std::string rtmp_server_url = "rtmp://localhost:1935/live/test";

std::stringstream command;
command << "ffmpeg ";

// infile options
command << "-y " // overwrite output files
<< "-an " // disable audio
<< "-f rawvideo " // force format to rawvideo
<< "-vcodec rawvideo " // force video rawvideo ('copy' to copy stream)
<< "-pix_fmt bgr24 " // set pixel format to bgr24
<< "-s 1280x720 " // set frame size (WxH or abbreviation)
<< "-r 30 "; // set frame rate (Hz value, fraction or abbreviation)

command << "-i - "; //

// outfile options
command << "-c:v libx264 " // Hyper fast Audio and Video encoder
<< "-pix_fmt yuv420p " // set pixel format to yuv420p
<< "-preset ultrafast " // set the libx264 encoding preset to ultrafast
<< "-f flv " // force format to flv
<< rtmp_server_url;

cv::Mat frame;

// 在子进程中调用 ffmpeg 进行推流
FILE *fp = nullptr;
fp = popen(command.str().c_str(), "w");

// 将 cv 读到的每一帧传入子进程
if (fp != nullptr) {
while (is_running) {
capture >> frame;
if (frame.empty()) {
continue;
}

fwrite(frame.data, sizeof(char), frame.total() * frame.elemSize(), fp);
}
pclose(fp);
return EXIT_SUCCESS;
} else {
return EXIT_FAILURE;
}
}

CMakeLists.txt:

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cmake_minimum_required(VERSION 3.20)
project(rtmp_test)

set(CMAKE_CXX_STANDARD 20)

message("")
message("Operation system is ${CMAKE_SYSTEM}")
if (CMAKE_SYSTEM_NAME MATCHES "Linux")
message("Current platform: Linux")
link_directories(/usr/local/lib)
include_directories(/usr/local/include)
message(STATUS "Load link directories from /usr/local/lib")
message(STATUS "Load include directories from /usr/local/include")
elseif (CMAKE_SYSTEM_NAME MATCHES "Darwin")
message("Current platform: Darwin")
link_directories(/opt/homebrew/lib)
include_directories(/opt/homebrew/include)
message(STATUS "Load link directories from /opt/homebrew/lib")
message(STATUS "Load include directories from /opt/homebrew/include")
SET(OPENSSL_ROOT_DIR /opt/homebrew/Cellar/openssl@1.1/1.1.1l)
SET(OPENSSL_INCLUDE_DIR /opt/homebrew/Cellar/openssl@1.1/1.1.1l/include)
else ()
message(FATAL_ERROR "Platform ${CMAKE_SYSTEM_NAME} is not support for this project")
endif ()

find_package(OpenCV REQUIRED)
include_directories(${OpenCV_INCLUDE_DIRS})

if (CMAKE_BUILD_TYPE STREQUAL Debug)
ADD_DEFINITIONS(-DDEBUG)
message(STATUS "CMake Build Type: Debug")
message("")
elseif (CMAKE_BUILD_TYPE STREQUAL Release)
message(STATUS "CMake Build Type: Release")
message("")
endif ()

file(GLOB ProjectSRC
"*.cc")

add_executable(${PROJECT_NAME} ${ProjectSRC})
target_link_libraries(${PROJECT_NAME} ${OpenCV_LIBS})