生成一个qt下使用opencv 进行 rtmp推流例程

你好，下面是一个基于 Qt 和 OpenCV 的 RTMP 推流示例：

首先，需要安装 ffmpeg 和 librtmp 库，这里以 Ubuntu 为例，使用以下命令进行安装：

sudo apt-get install libavcodec-dev libavformat-dev libavutil-dev libswscale-dev libavdevice-dev libavfilter-dev libavresample-dev librtmp-dev

然后，在 Qt 工程中添加以下头文件：

#include <opencv2/opencv.hpp>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavutil/avutil.h>
#include <libswscale/swscale.h>
#include <libavdevice/avdevice.h>
#include <libavfilter/avfilter.h>
#include <libavresample/avresample.h>
#include <librtmp/rtmp.h>

接着，定义 RTMP 推流的相关参数：

#define RTMP_URL "rtmp://xxxxx" // RTMP 服务器地址
#define WIDTH 640 // 视频宽度
#define HEIGHT 480 // 视频高度
#define FPS 25 // 视频帧率
#define BITRATE 500000 // 视频比特率

然后，初始化 ffmpeg 和 librtmp：

av_register_all();
avformat_network_init();
avdevice_register_all();
avcodec_register_all();
avfilter_register_all();
av_log_set_level(AV_LOG_INFO);

接着，打开摄像头并设置参数：

cv::VideoCapture cap(0);
cap.set(CV_CAP_PROP_FRAME_WIDTH, WIDTH);
cap.set(CV_CAP_PROP_FRAME_HEIGHT, HEIGHT);
cap.set(CV_CAP_PROP_FPS, FPS);

然后，创建 RTMP 推流句柄并连接 RTMP 服务器：

RTMP *rtmp = RTMP_Alloc();
RTMP_Init(rtmp);
RTMP_SetupURL(rtmp, RTMP_URL);
RTMP_EnableWrite(rtmp);
if (!RTMP_Connect(rtmp, NULL) || !RTMP_ConnectStream(rtmp, 0)) {
    qDebug() << "RTMP connect error";
    return -1;
}

接着，创建 AVFrame 和 AVPacket 并初始化：

AVFrame *frame = av_frame_alloc();
AVPacket *packet = av_packet_alloc();
memset(packet, 0, sizeof(AVPacket));

然后，设置帧参数：

frame->width = WIDTH;
frame->height = HEIGHT;
frame->format = AV_PIX_FMT_BGR24;
av_frame_get_buffer(frame, 0);

接着，开始推流：

while (true) {
    cap >> frame;
    if (frame.empty()) {
        break;
    }
    frame->pts = static_cast<int64_t>(av_gettime() / 1000.0 / 1000.0 * FPS);
    AVCodecContext *codec_context = rtmp->streams[0]->codec;
    codec_context->codec_tag = 0;
    codec_context->codec_id = AV_CODEC_ID_H264;
    codec_context->bit_rate = BITRATE;
    codec_context->width = WIDTH;
    codec_context->height = HEIGHT;
    codec_context->time_base.num = 1;
    codec_context->time_base.den = FPS;
    codec_context->gop_size = FPS * 2;
    codec_context->pix_fmt = AV_PIX_FMT_YUV420P;
    codec_context->max_b_frames = 0;
    codec_context->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
    AVCodec *codec = avcodec_find_encoder(codec_context->codec_id);
    if (!codec) {
        qDebug() << "Codec not found";
        return -1;
    }
    if (avcodec_open2(codec_context, codec, NULL) < 0) {
        qDebug() << "Could not open codec";
        return -1;
    }
    AVPixelFormat pixel_format = static_cast<AVPixelFormat>(frame->format);
    int width = frame->width;
    int height = frame->height;
    AVFrame *frame_yuv = av_frame_alloc();
    frame_yuv->format = AV_PIX_FMT_YUV420P;
    frame_yuv->width = width;
    frame_yuv->height = height;
    av_frame_get_buffer(frame_yuv, 0);
    SwsContext *sws_context = sws_getContext(width, height, pixel_format, width, height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
    sws_scale(sws_context, frame->data, frame->linesize, 0, height, frame_yuv->data, frame_yuv->linesize);
    avcodec_send_frame(codec_context, frame_yuv);
    av_frame_unref(frame_yuv);
    int ret = avcodec_receive_packet(codec_context, packet);
    if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
        continue;
    } else if (ret < 0) {
        qDebug() << "Error during encoding";
        return -1;
    }
    packet->stream_index = rtmp->streams[0]->id;
    RTMP_SendPacket(rtmp, packet, 1);
    av_packet_unref(packet);
    avcodec_free_context(&codec_context);
}

最后，关闭推流句柄和摄像头：

RTMP_Close(rtmp);
RTMP_Free(rtmp);
cap.release();

完整的 Qt 工程代码如下所示：

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <opencv2/opencv.hpp>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavutil/avutil.h>
#include <libswscale/swscale.h>
#include <libavdevice/avdevice.h>
#include <libavfilter/avfilter.h>
#include <libavresample/avresample.h>
#include <librtmp/rtmp.h>

#define RTMP_URL "rtmp://xxxxx" // RTMP 服务器地址
#define WIDTH 640 // 视频宽度
#define HEIGHT 480 // 视频高度
#define FPS 25 // 视频帧率
#define BITRATE 500000 // 视频比特率

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    av_register_all();
    avformat_network_init();
    avdevice_register_all();
    avcodec_register_all();
    avfilter_register_all();
    av_log_set_level(AV_LOG_INFO);

    cv::VideoCapture cap(0);
    cap.set(CV_CAP_PROP_FRAME_WIDTH, WIDTH);
    cap.set(CV_CAP_PROP_FRAME_HEIGHT, HEIGHT);
    cap.set(CV_CAP_PROP_FPS, FPS);

    RTMP *rtmp = RTMP_Alloc();
    RTMP_Init(rtmp);
    RTMP_SetupURL(rtmp, RTMP_URL);
    RTMP_EnableWrite(rtmp);
    if (!RTMP_Connect(rtmp, NULL) || !RTMP_ConnectStream(rtmp, 0)) {
        qDebug() << "RTMP connect error";
        return;
    }

    AVFrame *frame = av_frame_alloc();
    AVPacket *packet = av_packet_alloc();
    memset(packet, 0, sizeof(AVPacket));
    frame->width = WIDTH;
    frame->height = HEIGHT;
    frame->format = AV_PIX_FMT_BGR24;
    av_frame_get_buffer(frame, 0);

    while (true) {
        cap >> frame;
        if (frame.empty()) {
            break;
        }
        frame->pts = static_cast<int64_t>(av_gettime() / 1000.0 / 1000.0 * FPS);
        AVCodecContext *codec_context = rtmp->streams[0]->codec;
        codec_context->codec_tag = 0;
        codec_context->codec_id = AV_CODEC_ID_H264;
        codec_context->bit_rate = BITRATE;
        codec_context->width = WIDTH;
        codec_context->height = HEIGHT;
        codec_context->time_base.num = 1;
        codec_context->time_base.den = FPS;
        codec_context->gop_size = FPS * 2;
        codec_context->pix_fmt = AV_PIX_FMT_YUV420P;
        codec_context->max_b_frames = 0;
        codec_context->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
        AVCodec *codec = avcodec_find_encoder(codec_context->codec_id);
        if (!codec) {
            qDebug() << "Codec not found";
            return;
        }
        if (avcodec_open2(codec_context, codec, NULL) < 0) {
            qDebug() << "Could not open codec";
            return;
        }
        AVPixelFormat pixel_format = static_cast<AVPixelFormat>(frame->format);
        int width = frame->width;
        int height = frame->height;
        AVFrame *frame_yuv = av_frame_alloc();
        frame_yuv->format = AV_PIX_FMT_YUV420P;
        frame_yuv->width = width;
        frame_yuv->height = height;
        av_frame_get_buffer(frame_yuv, 0);
        SwsContext *sws_context = sws_getContext(width, height, pixel_format, width, height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
        sws_scale(sws_context, frame->data, frame->linesize, 0, height, frame_yuv->data, frame_yuv->linesize);
        avcodec_send_frame(codec_context, frame_yuv);
        av_frame_unref(frame_yuv);
        int ret = avcodec_receive_packet(codec_context, packet);
        if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
            continue;
        } else if (ret < 0) {
            qDebug() << "Error during encoding";
            return;
        }
        packet->stream_index = rtmp->streams[0]->id;
        RTMP_SendPacket(rtmp, packet, 1);
        av_packet_unref(packet);
        avcodec_free_context(&codec_context);
    }

    RTMP_Close(rtmp);
    RTMP_Free(rtmp);
    cap.release();

    av_frame_free(&frame);
    av_packet_free(&packet);
}

MainWindow::~MainWindow()
{
    delete ui;
}

请注意：这个例程只是一个简单的示例，还需要进行错误处理、内存管理等等。