ffmepg 录屏推流 c++示例

这里提供一个使用 ffmpeg 库进行屏幕录制并推流的 C++ 示例代码：

#include <iostream>
#include <thread>
#include <chrono>
#include <cstring>

extern "C" {
    #include <libavcodec/avcodec.h>
    #include <libavformat/avformat.h>
    #include <libavutil/avutil.h>
    #include <libavutil/opt.h>
    #include <libswscale/swscale.h>
    #include <libswresample/swresample.h>
}

#ifdef _WIN32
#include <Windows.h>
#include <d3d9.h>

#pragma comment(lib, "d3d9.lib")
#endif

#define WIDTH 1280
#define HEIGHT 720
#define FPS 30
#define BITRATE 2000000
#define STREAM_URL "rtmp://localhost/live/stream"

int main() {
    av_register_all();
    avcodec_register_all();

    AVFormatContext *format_ctx = nullptr;
    AVOutputFormat *output_fmt = nullptr;
    AVCodecContext *codec_ctx = nullptr;
    AVCodec *codec = nullptr;
    AVStream *stream = nullptr;
    AVFrame *frame = nullptr;
    AVPacket packet;
    SwsContext *sws_ctx = nullptr;

    // 创建输出格式上下文
    avformat_alloc_output_context2(&format_ctx, nullptr, "flv", STREAM_URL);
    if (!format_ctx) {
        std::cerr << "Could not create output context" << std::endl;
        return -1;
    }

    // 查找视频编码器
    codec = avcodec_find_encoder(AV_CODEC_ID_H264);
    if (!codec) {
        std::cerr << "Could not find encoder" << std::endl;
        return -1;
    }

    // 创建视频流
    stream = avformat_new_stream(format_ctx, codec);
    if (!stream) {
        std::cerr << "Could not create stream" << std::endl;
        return -1;
    }

    codec_ctx = avcodec_alloc_context3(codec);
    if (!codec_ctx) {
        std::cerr << "Could not allocate codec context" << std::endl;
        return -1;
    }

    // 配置编码器参数
    codec_ctx->codec_id = codec->id;
    codec_ctx->width = WIDTH;
    codec_ctx->height = HEIGHT;
    codec_ctx->bit_rate = BITRATE;
    codec_ctx->time_base = (AVRational){1, FPS};
    codec_ctx->gop_size = 10;
    codec_ctx->pix_fmt = AV_PIX_FMT_YUV420P;

    // 设置编码器的质量
    av_opt_set(codec_ctx->priv_data, "preset", "ultrafast", 0);
    av_opt_set(codec_ctx->priv_data, "tune", "zerolatency", 0);

    // 打开编码器
    if (avcodec_open2(codec_ctx, codec, nullptr) < 0) {
        std::cerr << "Could not open codec" << std::endl;
        return -1;
    }

    // 设置视频流参数
    avcodec_parameters_from_context(stream->codecpar, codec_ctx);

    // 打开输出流
    if (avio_open(&format_ctx->pb, STREAM_URL, AVIO_FLAG_WRITE) < 0) {
        std::cerr << "Could not open output stream" << std::endl;
        return -1;
    }

    // 写入头信息
    avformat_write_header(format_ctx, nullptr);

#ifdef _WIN32
    // 初始化 Direct3D
    IDirect3D9* d3d = Direct3DCreate9(D3D_SDK_VERSION);
    if (!d3d) {
        std::cerr << "Could not create Direct3D object" << std::endl;
        return -1;
    }

    // 创建 Direct3D 设备对象
    D3DPRESENT_PARAMETERS d3dpp = {0};
    d3dpp.Windowed = TRUE;
    d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
    d3dpp.BackBufferFormat = D3DFMT_UNKNOWN;
    d3dpp.hDeviceWindow = GetDesktopWindow();
    IDirect3DDevice9* device = nullptr;
    if (FAILED(d3d->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, d3dpp.hDeviceWindow,
                                  D3DCREATE_SOFTWARE_VERTEXPROCESSING, &d3dpp, &device))) {
        std::cerr << "Could not create Direct3D device" << std::endl;
        return -1;
    }

    // 创建 D3D 表面对象
    IDirect3DSurface9* surface = nullptr;
    if (FAILED(device->CreateOffscreenPlainSurface(WIDTH, HEIGHT, D3DFMT_X8R8G8B8,
                                                    D3DPOOL_SYSTEMMEM, &surface, nullptr))) {
        std::cerr << "Could not create surface object" << std::endl;
        return -1;
    }
#endif

    // 分配内存
    frame = av_frame_alloc();
    av_image_alloc(frame->data, frame->linesize, codec_ctx->width, codec_ctx->height,
                   codec_ctx->pix_fmt, 32);

    // 初始化转换上下文
    sws_ctx = sws_getContext(codec_ctx->width, codec_ctx->height, AV_PIX_FMT_BGRA,
                             codec_ctx->width, codec_ctx->height, codec_ctx->pix_fmt,
                             SWS_BICUBIC, nullptr, nullptr, nullptr);

    while (true) {
#ifdef _WIN32
        // 从 D3D 表面对象中获取像素数据
        if (FAILED(device->GetFrontBufferData(0, surface))) {
            std::cerr << "Could not get front buffer data" << std::endl;
            continue;
        }

        D3DLOCKED_RECT rect;
        if (FAILED(surface->LockRect(&rect, nullptr, D3DLOCK_READONLY))) {
            std::cerr << "Could not lock surface rect" << std::endl;
            continue;
        }

        // 将像素数据复制到 AVFrame 中
        uint8_t *dst_data[4] = {frame->data[0], nullptr, nullptr, nullptr};
        int dst_linesize[4] = {frame->linesize[0], 0, 0, 0};
        uint8_t *src_data[1] = {(uint8_t*)rect.pBits};
        int src_linesize[1] = {rect.Pitch};
        sws_scale(sws_ctx, src_data, src_linesize, 0, codec_ctx->height, dst_data, dst_linesize);

        surface->UnlockRect();
#else
        // TODO: 获取像素数据的代码 (Linux/MacOS)
#endif

        // 编码帧
        frame->pts = av_gettime();
        int ret = avcodec_send_frame(codec_ctx, frame);
        if (ret < 0) {
            std::cerr << "Error sending frame" << std::endl;
            continue;
        }

        while (ret >= 0) {
            ret = avcodec_receive_packet(codec_ctx, &packet);
            if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
                break;
            } else if (ret < 0) {
                std::cerr << "Error receiving packet" << std::endl;
                continue;
            }

            // 发送数据包
            av_interleaved_write_frame(format_ctx, &packet);
            av_packet_unref(&packet);
        }

        std::this_thread::sleep_for(std::chrono::milliseconds(1000 / FPS));
    }

    // 清理资源
    av_write_trailer(format_ctx);
    avcodec_free_context(&codec_ctx);
    avformat_free_context(format_ctx);
    av_frame_free(&frame);
    sws_freeContext(sws_ctx);

    return 0;
}

这个示例代码使用了 Direct3D 技术获取屏幕像素数据，因此需要在 Windows 操作系统上运行。如果需要在其他平台上运行，需要修改获取像素数据的代码。