FFMPEG+Qt 实时显示本机USB摄像头1080p画面以及同步录制mp4视频

#include "camerathread.h" #include <iostream> #include <QDebug> CameraThread::CameraThread() { } CameraThread::~CameraThread() { if (thread_) { Stop(); } } int CameraThread::Init(const char *url) { int ret = 0; url_ = url; avdevice_register_all(); // 注册所有设备 h264_pkt = av_packet_alloc();//存读取和编码后的H264数据 captured_packet = av_packet_alloc(); qDebug()<<"CameraThread::Init Success!"; return 0; } int CameraThread::Start() { start_pts = 0; int ret = 0; /******************************************打开摄像头设备********************************************/ const AVInputFormat* m_inputFormat = av_find_input_format("dshow"); inputContext = avformat_alloc_context(); AVDictionary *options = nullptr; // av_dict_set(&options, "pixel_format", "yuyv422", 0); // 设置为 YUV420P // av_dict_set(&options, "video_size", "640x480", 0); // 设置分辨率为 640x480 默认1920*1080 // av_dict_set_int(&options, "rtbufsize", 3041280 * 50, 0);//默认大小3041280 // av_dict_set(&options, "rtbufsize", "10M", 0); // 设置为 10MB ret = avformat_open_input(&inputContext, url_.c_str(), m_inputFormat, &options); if (ret < 0){ qDebug()<<"avformat_open_input failed, ret: "<<ret; return -1; } // 获取摄像头流信息 ret = avformat_find_stream_info(inputContext, nullptr); if (ret < 0){ qDebug()<<"Could not retrieve input stream information"; return -1; } int videoStreamId = -1; videoStreamId = av_find_best_stream(inputContext, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, NULL); inputStream = inputContext->streams[videoStreamId]; codecParameters = inputStream->codecpar; // 获取摄像头的实际分辨率和帧率 int actual_width = codecParameters->width; int actual_height = codecParameters->height; AVRational actual_frame_rate = inputStream->r_frame_rate; qDebug()<< "Camera Resolution: " << actual_width << "x" << actual_height; qDebug()<< "Camera Frame Rate: " << actual_frame_rate.num << "/" << actual_frame_rate.den << " fps"; /******************************************创建解码器********************************************/ // 查找解码器 auto codec_id = inputStream->codecpar->codec_id; const AVCodec* decoder = avcodec_find_decoder(codec_id); if (!decoder) { qDebug()<<"Unsupported codec !"; return -1; } // 创建解码器上下文 decoderContext = avcodec_alloc_context3(decoder); ret = avcodec_parameters_to_context(decoderContext, codecParameters); if (ret<0) { qDebug()<<"Failed to copy codec parameters to decoder context."; return -1; } qDebug() << " output pix_fmt=" << av_get_pix_fmt_name((AVPixelFormat)codecParameters->format) <<" "<< codecParameters->format; ret = avcodec_open2(decoderContext, decoder, nullptr); if (ret<0) { qDebug()<<"Failed to open decoder."; return -1; } /******************************************创建编码器********************************************/ // 查找 H.264 编码器 const AVCodec* pEncoderH264 = avcodec_find_encoder(AV_CODEC_ID_H264); if (pEncoderH264 == NULL) { qDebug() << "Unsupported encodec."; return -1; } //视频编码器上下文 encoderContext = avcodec_alloc_context3(pEncoderH264); encoderContext->time_base.num = inputStream->time_base.num; encoderContext->time_base.den = inputStream->time_base.den; encoderContext->has_b_frames = 0; // encoderContext->gop_size = 50; encoderContext->codec_id = pEncoderH264->id; encoderContext->pix_fmt = (AVPixelFormat)inputStream->codecpar->format; qDebug()<<"111111111111111111111111111111: "<<encoderContext->pix_fmt; encoderContext->width = inputStream->codecpar->width; encoderContext->height = inputStream->codecpar->height; // encoderContext->bit_rate = 0; encoderContext->flags |= AV_CODEC_FLAG_GLOBAL_HEADER; encoderContext->framerate = inputStream->avg_frame_rate;//编码帧率按照采集帧率来 // encoderContext->bit_rate = 5000000; //数值越小文件越小 //编码器不用等待缓冲区填满，接收到数据即开始编码 av_opt_set(encoderContext->priv_data, "tune", "zerolatency", 0); // av_opt_set(encoderContext->priv_data, "crf", "23", 0); //数值越大越模糊，存储文件越小 qDebug() << "encoder h246 information:"; qDebug() << " encode fps=" << (encoderContext->framerate.num / encoderContext->framerate.den) ; qDebug() << " w=" << encoderContext->width << ", h=" << encoderContext->height; qDebug() << " input pix format=" << av_get_pix_fmt_name(encoderContext->pix_fmt) <<" "<< encoderContext->pix_fmt ; ret = avcodec_open2(encoderContext, pEncoderH264, NULL); if (ret < 0) { qDebug() <<"avcodec_open2"; return -1; } /******************************************创建视频输出文件********************************************/ const AVOutputFormat* outputFormat = av_guess_format("mp4", NULL, NULL); outputContext = avformat_alloc_context(); outputContext->oformat = const_cast<AVOutputFormat*>(outputFormat); // 创建输出流 outputStream = avformat_new_stream(outputContext, encoderContext->codec); if (!outputStream){ qDebug() <<"Failed to create output stream"; return -1; } avcodec_parameters_from_context(outputStream->codecpar, encoderContext); outputStream->time_base = av_inv_q(inputStream->r_frame_rate); // 创建输出 MP4 文件 mp4_count++; m_mp4_file_name = m_mp4_file_name_header + std::to_string(mp4_count) + ".mp4"; ret = avio_open(&outputContext->pb, m_mp4_file_name.c_str(), AVIO_FLAG_WRITE); if(ret <0) { qDebug() <<"Failed to create output file."; return -1; } ret = avformat_write_header(outputContext, NULL); if(ret <0) { qDebug() <<"Failed to write header"; return -1; } /******************************************开线程****************************************************/ thread_ = new std::thread(&CameraThread::Run, this); if (!thread_) { qDebug()<<"new std::thread(&CameraThread::Run, this) failed"; return -1; } return 0; } int CameraThread::Stop() { Thread::Stop(); // 写入文件尾 av_write_trailer(outputContext); abort_ = 0; start_pts = 0; // 释放资源 avcodec_free_context(&encoderContext); avformat_close_input(&inputContext); if (!(outputContext->oformat->flags & AVFMT_NOFILE)) { avio_closep(&outputContext->pb); } avformat_free_context(outputContext); qDebug() << "Recording finished and saved to output.mp4." ; return 0; } void CameraThread::Run() { qDebug() << "Run into CameraThread::Run()!"; int ret = 0; SwsContext *sws_ctx = nullptr; while (!abort_) { // 读取视频帧 ret = av_read_frame(inputContext, captured_packet); if (ret < 0) { qDebug() << "av_read_frame error"; continue; // 如果读取失败，跳过到下一帧 } // start capture pts from 0 // 初始化 start_pts if (start_pts == 0) { start_pts = captured_packet->pts; // 仅在第一次读取时设置 } captured_packet->pts -= start_pts; qDebug()<<"captured_packet->pts: "<<captured_packet->pts; av_log(nullptr, AV_LOG_INFO, "packet size is %d\n", captured_packet->size); // 解码 MJPEG 数据 ret = avcodec_send_packet(decoderCo