您好，我在win11系统下使用qt5，ffmpeg抓取桌面并向网络推流时，代码阻塞在avformat_write_header函数中，既不报错，又不向下运行，不知道是否是相关参数设置的有问题？使用gdigrab抓取桌面，进行h264编码，以RTSP协议进行推流。以下是我的代码。万分感谢！
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QDebug>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
avcodec_configuration();
unsigned version = avcodec_version();
QString ch = QString::number(version,10);
qDebug()<<"version: "<<version;
//==================================变量定义==========================================//
//抓屏变量定义
AVFormatContext* pInputFormatContext = NULL;
AVCodec* pInputCodec = NULL;
AVCodecContext* pInputCodecContex = NULL;
//输出流变量定义
AVFormatContext* pOutputFormatContext = NULL;
AVCodecContext* pOutCodecContext = NULL;
AVCodec* pOutCodec = NULL;
AVStream* pOutStream = NULL;
//=============================================================================================//
//**********注册ffmpeg相关组件**********//
av_register_all();
avformat_network_init();
avdevice_register_all();
//=================================输入(Input)抓屏部分设置======================================//
int ret, i;
int videoindex = -1;
//为数据类型AVFormatContext的结构体初始化并分配默认值
pInputFormatContext = avformat_alloc_context();
AVDictionary* options = NULL;
AVInputFormat* ifmt = av_find_input_format("gdigrab");//AVInputFormat存储输入视音频使用的封装格式
//相关参数设置
av_dict_set(&options, "framerate", "25", 0);
av_dict_set(&options, "video_size", "1920x1080", 0);
av_dict_set(&options, "start_time_realtime", 0, 0);
////Grab at position 0,0 真正的打开文件
//这个函数读取文件的头部并且把信息保存到我们给的AVFormatContext结构体的ifomat,priv_data,nb_streams,streams,filename,start_time,duration中
if (avformat_open_input(&pInputFormatContext, "desktop", ifmt, &options) != 0) {
printf("Couldn't open input stream.\n");
getchar();
//return -1;
}
pInputFormatContext->probesize = 42*1024*1024;
if ((ret = avformat_find_stream_info(pInputFormatContext, 0)) < 0) {
printf("Failed to retrieve input stream information");
getchar();
//return -1;
}
//打印输入流信息
av_dump_format(pInputFormatContext, 0, "desktop", 0);
for (i = 0; pInputFormatContext->nb_streams; i++)
if (pInputFormatContext->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
//std::cout << "pInputFormatContext=" << pInputFormatContext->streams[i]->codec->bit_rate << std::endl;
videoindex = i;
break;
}
//输入流解码器初始化
pInputCodecContex = pInputFormatContext->streams[videoindex]->codec;
pInputCodecContex->flags |= 0x00080000;//代表什么？？？？？？？
pInputCodec = avcodec_find_decoder(pInputCodecContex->codec_id);
if (pInputCodec == NULL)
{
printf("Codec not found.\n");
getchar();
//return -1;
}
//打开解码器
if (avcodec_open2(pInputCodecContex, pInputCodec, NULL) < 0)
{
printf("Could not open codec.\n");
getchar();
//return -1;
}
//为一帧图像分配内存
AVFrame* pFrame;
AVFrame* pFrameYUV;
pFrame = av_frame_alloc();
pFrameYUV = av_frame_alloc();//为转换来申请一帧的内存(把原始帧->YUV)
pFrameYUV->format = AV_PIX_FMT_YUV420P;
pFrameYUV->width = pInputCodecContex->width;
pFrameYUV->height = pInputCodecContex->height;
unsigned char* out_buffer = (unsigned char*)av_malloc(avpicture_get_size(AV_PIX_FMT_YUV420P, pInputCodecContex->width, pInputCodecContex->height));
//现在我们使用avpicture_fill来把帧和我们新申请的内存来结合
avpicture_fill((AVPicture*)pFrameYUV, out_buffer, AV_PIX_FMT_YUV420P, pInputCodecContex->width, pInputCodecContex->height);
//格式转换的初始化，转换成YUV
struct SwsContext* img_convert_ctx;
img_convert_ctx = sws_getContext(pInputCodecContex->width, pInputCodecContex->height, pInputCodecContex->pix_fmt, pInputCodecContex->width, pInputCodecContex->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
//=============================================================================================//
//==============================编码器、RTSP推流=======================================//
const char* out_file = "rtsp://localhost/sonar"; //推流地址
//输出流配置
//定义一个输出流信息的结构体
avformat_alloc_output_context2(&pOutputFormatContext, NULL, "rtsp", out_file);
if (!pOutputFormatContext) {
printf("Could not create output context\n");
ret = AVERROR_UNKNOWN;
getchar();
//return -1;
}
av_opt_set(pOutputFormatContext->priv_data, "rtsp_transport", "tcp", 0);
pOutputFormatContext->oformat->video_codec = AV_CODEC_ID_H264;
//查找编码器
pOutCodec = avcodec_find_encoder(AV_CODEC_ID_H264);
if (!pOutCodec) {
printf("Can not find encoder! \n");
getchar();
//return -1;
}
pOutCodecContext = avcodec_alloc_context3(pOutCodec);
pOutCodecContext->flags |= 0x00080000;//flags变量含义？？？？？？
//输出流编码器配置必须设置的参数
//pOutCodecContext = pOutStream->codec;
pOutCodecContext->codec_id = AV_CODEC_ID_H264;
pOutCodecContext->codec_type = AVMEDIA_TYPE_VIDEO;
//像素格式,
pOutCodecContext->pix_fmt = AV_PIX_FMT_YUV420P;
//size
pOutCodecContext->width = pInputCodecContex->width;
pOutCodecContext->height = pInputCodecContex->height;
//目标码率
pOutCodecContext->bit_rate = 1000;// 4000000;
//每250帧插入一个I帧,I帧越小视频越小
pOutCodecContext->gop_size = 1;// 10;
//Optional Param B帧
pOutCodecContext->max_b_frames = 0; //设置B帧为0，则DTS与PTS一致
//时基
pOutCodecContext->time_base.num = 1;
pOutCodecContext->time_base.den = 20;// 25;
//H264
//pCodecCtx->me_range = 16;
//pCodecCtx->max_qdiff = 4;
//pCodecCtx->qcompress = 0.6;
//最大和最小量化系数
pOutCodecContext->qmin = 10;
pOutCodecContext->qmax = 51;
//if (pOutputFormatContext->oformat->flags & AVFMT_GLOBALHEADER)
//pOutCodecContext->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
AVDictionary* param = 0;
//H.264编码参数设置
av_opt_set(pOutCodecContext->priv_data, "preset", "superfast", 0);
//av_opt_set(pOutCodecContext->priv_data, "tune", "zerolatency", 0);//实时编码
//打开编码器
if (avcodec_open2(pOutCodecContext, pOutCodec, ¶m) < 0)
{
printf("Failed to open encoder! \n");
getchar();
//return -1;
}
//创建输出流，初步设置
pOutStream = avformat_new_stream(pOutputFormatContext, pOutCodec);
if (pOutStream == NULL)
{
printf("Failed create pOutStream!\n");
getchar();
//return -1;
}
pOutStream->time_base.num = 1;
pOutStream->time_base.den = 20;
pOutStream->start_time = 0;
pOutStream->duration = 0;
avcodec_parameters_from_context(pOutStream->codecpar, pOutCodecContext);
pOutStream->codec->codec = pOutCodecContext->codec;
//pOutputFormatContext->streams[0]->codec->codec = pOutCodecContext->codec;
//=============================================================================================//
//================================向流中写入数据======================================//
//写文件头
//av_dict_set(¶m, "stimeout", "3000000", 0);//超时强制退出avformat_write_header
int r = -1;
r = avformat_write_header(pOutputFormatContext, ¶m);
if (r < 0)
{
printf("Failed write header!\n");
getchar();
//return -1;
}
AVPacket* packet = (AVPacket*)av_malloc(sizeof(AVPacket));
int got_picture;
AVPacket pkt;
int picture_size = avpicture_get_size(pOutCodecContext->pix_fmt, pOutCodecContext->width, pOutCodecContext->height);
av_new_packet(&pkt, picture_size);
int frame_index = 0;
while ((av_read_frame(pInputFormatContext, packet)) >= 0)
{
printf("to av_read_frame! \n");
if (packet->stream_index == videoindex)
{
//真正解码,packet to pFrame
avcodec_decode_video2(pInputCodecContex, pFrame, &got_picture, packet);
//printf("真正解码,packet to pFrame! \n%d", got_picture);
if (got_picture)
{
sws_scale(img_convert_ctx, (const unsigned char* const*)pFrame->data, pFrame->linesize, 0, pInputCodecContex->height, pFrameYUV->data, pFrameYUV->linesize);
pFrameYUV->pts = frame_index;
int picture;
//真正编码pkt
int ret = avcodec_encode_video2(pOutCodecContext, &pkt, pFrameYUV, &picture);
//pkt.pts = frame_index;
//pkt.dts = pkt.pts;
if (ret < 0) {
printf("Failed to encode! \n");
getchar();
//return -1;
}
if (picture == 1)
{
pkt.stream_index = pOutStream->index;
AVRational time_base = pOutStream->time_base;//{ 1, 1000 };
AVRational r_framerate1 = { 50, 2 };//{ 50, 2 };
int64_t calc_pts = (double)frame_index * (AV_TIME_BASE)* (1 / av_q2d(r_framerate1));
pkt.pts = av_rescale_q(calc_pts, { 1, AV_TIME_BASE }, time_base); //enc_pkt.pts = (double)(framecnt*calc_duration)*(double)(av_q2d(time_base_q)) / (double)(av_q2d(time_base));
pkt.dts = pkt.pts;
frame_index++;
ret = av_interleaved_write_frame(pOutputFormatContext, &pkt);//推流到RTSP
//av_dump_format(pOutputFormatContext, 0, out_file, 1);
if (ret < 0) {
printf("Error muxing packet\n");
break;
}
av_free_packet(&pkt);
}
}
}
av_free_packet(packet);
}
//写文件尾
av_write_trailer(pOutputFormatContext);
//=============================================================================================//
//释放变量
sws_freeContext(img_convert_ctx);
//fclose(fp_yuv);
av_free(out_buffer);
av_free(pFrameYUV);
av_free(pFrame);
avcodec_close(pInputCodecContex);
avformat_close_input(&pInputFormatContext);
avcodec_close(pOutStream->codec);
av_free(pOutCodec);
avcodec_close(pOutCodecContext);
avformat_free_context(pOutputFormatContext);
}
MainWindow::~MainWindow()
{
delete ui;
}
根据您提供的代码，问题可能是由于网络推流配置不正确导致阻塞在avformat_write_header函数。以下是几个可能的原因和解决方法：
检查RTSP推流地址：确保指定的RTSP推流地址正确，并且目标服务器可以接收和处理推流数据。您可以尝试使用其他RTSP推流地址进行测试，以确定是否是地址配置的问题。
检查输出流编码器配置：确保输出流编码器（H.264）的相关参数正确设置。例如，检查像素格式（pix_fmt）、视频大小（width和height）、目标码率（bit_rate）、关键帧间隔（gop_size）等参数是否符合要求。
确认编码器是否可用：使用avcodec_find_encoder函数查找H.264编码器时，确保编码器可用并且已成功加载。如果编码器未正确加载，可能需要检查FFmpeg的配置和安装是否正确。
检查编码器上下文：在设置输出流编码器的上下文（pOutCodecContext）之前，确保已正确分配和初始化该上下文。您可以尝试添加以下代码：
pOutCodecContext = avcodec_alloc_context3(pOutCodec);
if (!pOutCodecContext) {
printf("Failed to allocate output codec context.\n");
getchar();
// return -1;
}
这样可以确保正确分配输出流编码器的上下文。
检查网络配置：确保您的网络环境正常，没有防火墙或网络限制导致无法推流。可以尝试在其他网络环境中运行代码，看是否能够成功推流。
媒体服务的问题，可能是流媒体服务器没打开，要么就是推流地址与 媒体服务器地址不对应