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• Qt 5.2 / OpenCV 2.4.8 - Can’t open video files via VideoCapture

  21 février 2014, par Zamahra

  I have a big problem that i can’t solve by myself. OpenCV itself works fine, but i’m not able to load videos. Here’s my code :

  PRO- File

  QT       += core gui
  
  
  
  greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
  
  
  
  TARGET = videoredux
  
  TEMPLATE = app
  
  
  
  INCLUDEPATH += C:/OpenCV/opencv_bin/install/include
  
  LIBS += -LC:\\OpenCV\\opencv_bin\\bin \
  
      libopencv_core248d \
  
      libopencv_highgui248d \
  
      libopencv_imgproc248d \
  
      libopencv_features2d248d \
  
      libopencv_calib3d248d \
  
      libopencv_video248d \
  
  
  
  
  
  SOURCES += main.cpp\
  
          mainwindow.cpp
  
  
  
  HEADERS  += mainwindow.h
  
  
  
  FORMS    += mainwindow.ui

  and the MainWindow Class :

  #include "mainwindow.h"
  
  #include "ui_mainwindow.h"
  
  #include <qfiledialog>
  
  #include <iostream>
  
  #include 
  
  #include <opencv2></opencv2>core/core.hpp>
  
  #include <opencv2></opencv2>highgui/highgui.hpp>
  
  #include <opencv2></opencv2>imgproc/imgproc.hpp>
  
  #include <opencv></opencv>cv.h>
  
  
  
  
  
  MainWindow::MainWindow(QWidget *parent) :
  
  QMainWindow(parent),
  
  ui(new Ui::MainWindow)
  
  {
  
      ui->setupUi(this);
  
      ui->videoStatusLabel->setText("Kein Video geladen.");
  
  
  
      // SIGNALS &amp; SLOTS
  
  
  
      QObject::connect(ui->chooseVideoButton,SIGNAL(clicked()),
  
                   this,SLOT(chooseVideo()));
  
      QObject::connect(ui->startButton,SIGNAL(clicked()),
  
                   this,SLOT(startProcess()));
  
  
  
  }
  
  
  
  void MainWindow::chooseVideo(){
  
  
  
      QString fileName = QFileDialog::getOpenFileName(this,
  
           tr("Open Video"), "/home", tr("Video Files (*.avi *.mp4 *.mpeg *.mpg)"));
  
      qDebug() &lt;&lt; "Path:" &lt;&lt; fileName;
  
      ui->videoStatusLabel->setText(fileName);
  
  }
  
  
  
  void MainWindow::startProcess(){
  
      QString videoPath = ui->videoStatusLabel->text();
  
      QFileInfo video(videoPath);
  
      if(video.exists()){
  
          const std::string path = videoPath.toUtf8().constData();
  
          cv::VideoCapture capture(path);
  
          cv::Mat frame;
  
  
  
          if(!capture.isOpened()){
  
              qDebug() &lt;&lt; "Error, video not loaded";
  
          }
  
  
  
          cv::namedWindow("window",1);
  
          while(true)
  
          {
  
              bool success = capture.read(frame);
  
              if(success == false){
  
                  break;
  
              }
  
              cv::imshow("window",frame);
  
              cv::waitKey(20);
  
          }
  
          cv::waitKey(0);
  
      }
  
      else{
  
          qDebug() &lt;&lt; "Error, File doesn&#39;t exist";
  
      }
  
  }
  
  </iostream></qfiledialog>

  The paths are correct, I tried many different video formats but he never loads the videos. I’m running Qt on a Windows 8 machine and i have “K-Lite Codec Pack 10.2.0 Basic” and ffmpeg installed. The videos are playing properly with my video players. I also tried to copy the .dll to the working directory, searched for opencv dll's in the system32 directory and rebuild OpenCV with mingw on this computer. I know that many people have the same problems, but none of their suggestions solved it. Does anyone know how to solve this problem ?

  Thank you very much !

  Nadine

  ----UPDATE---- I still can't open video files, so I programmed the application on a Windows7 64-Bit system. It worked fine, but when I try to open the application on a Windows8 computer it still can't open the file. It doesn't matter which codecs are installed, because it generally runs on every Windows7 computer and fails on every Windows8 computer.. The same for older OpenCV-Versions. Is there a general problem with OpenCV and Windows8 ?

• Rotate video according to rotation metadata and strip off metadata using ffmpeg [on hold]

  12 décembre 2018, par this.lau_

  I’ve got a video with the following metadata :

  Metadata:
  
    rotate          : 90
  
    creation_time   : 2018-12-03T16:13:47.000000Z
  
    handler_name    : VideoHandle
  
  Side data:
  
    displaymatrix: rotation of -90.00 degrees

  And I would like to remove this metadata and rotate the video by whatever rotation value is found there (in this case -90 but it can be anything).

  The result will be a video with the correct orientation and that works with all video players (including those that don’t auto-rotate based on the metadata).

  I’ve tried various commands but couldn’t find anything that would work. Any idea how to do this ?

• Not able to play .mpd file of MPEG-DASH stream

  29 novembre 2018, par JAVA Coder

  I have made segments of a mp4 file and uploaded all .m4s segments,.initmp4 file and the .mpd file to s3 bucket and used the url of .mpd file to play the full file using online DASH players of akamai,bitmovin,videoJs,dashJs etc but failed.

  When I tried to play the .mpd file by using GPAC MP4Client on command prompt just can hear the audio with a blank screen.

  You can find the commands here which I have used to make segments of the mp4 file.