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• C++ OpenCV 3.4 / FFMPEG 3.4.1 VideoWriter and MP4 Output File Format

  11 janvier 2019, par PhilBot

  I’m running on an ARM BeagleBone X-15 Debian machine with Linux Kernel 4.9.35-ti-r44. In my C++ ( Qt 5 ) application, I want to save my cv::Mat frames to an MP4 format video. I have libx264 installed and compiled from scratch both ffmpeg and OpenCv. I can successfully record and view video with MJPEG with the AVI video container type but not MP4. Whenever I try to write an MP4 video, I get run time errors of the form :

  OpenCV: FFMPEG: tag 0x44495658/'XVID' is not supported with codec id 13 and format 'mp4 / MP4 (MPEG-4 Part 14)'
  
  OpenCV: FFMPEG: fallback to use tag 0x00000020/' ???'

  I’ve tried various Google answers but none have worked.

  Relevant code :

  cv::Size frameSize = frame.size();
  
  
  
  qDebug() << "Initializing Video Recording to save Video file here: " << destinationFileName;
  
  
  
  std::string filename = destinationFileName.toStdString();
  
  //int fcc =   CV_FOURCC('M','J','P','G');
  
  //int fcc =   CV_FOURCC('X','2','6','4');
  
  int fcc = CV_FOURCC('X','V','I','D');
  
  int fps =   1;
  
  videoRecorder = new cv::VideoWriter(filename,fcc,fps,frameSize);
  
  
  
  ...
  
  
  
  videoRecorder->write(frame);

  I’ve downloaded and built the latest OpenCV 3.4 but the problem persists.
  How can I write to an MP4 File with OpenCV’s video writer ?

  When I try the ’X’,’2’,’6’,’4’ format I get the error :

      Initializing Video Recording to save Video file here:  "/tmp/Garage.mp4"
  
  OpenCV: FFMPEG: tag 0x34363258/'X264' is not supported with codec id 28 and format 'mp4 / MP4 (MPEG-4 Part 14)'
  
  OpenCV: FFMPEG: fallback to use tag 0x31637661/'avc1'
  
  [h264_v4l2m2m @ 0x81042020] Could not find a valid device
  
  [h264_v4l2m2m @ 0x81042020] can't configure encoder
  
  Could not open codec 'h264_v4l2m2m': Unspecified error
  
  Starting

  When I try the ’X’,’V’,’I’,’D’ format I get the error :

  Initializing Video Recording to save Video file here:  "/tmp/Garage.mp4"
  
  OpenCV: FFMPEG: tag 0x44495658/'XVID' is not supported with codec id 13 and format 'mp4 / MP4 (MPEG-4 Part 14)'
  
  OpenCV: FFMPEG: fallback to use tag 0x7634706d/'mp4v'
  
  Starting

  When I try the ’M’,’P’,’E’,’G’ format I get the error :

  Initializing Video Recording to save Video file here:  "/tmp/Garage.mp4"
  
  OpenCV: FFMPEG: tag 0x4745504d/'MPEG' is not supported with codec id 2 and format 'mp4 / MP4 (MPEG-4 Part 14)'
  
  OpenCV: FFMPEG: fallback to use tag 0x7634706d/'mp4v'
  
  Starting

  When I try the ’H’,’2’,’6’,’4’ format I get the error :

  OpenCV: FFMPEG: tag 0x34363248/'H264' is not supported with codec id 28 and format 'mp4 / MP4 (MPEG-4 Part 14)'
  
  OpenCV: FFMPEG: fallback to use tag 0x31637661/'avc1'
  
  [h264_v4l2m2m @ 0x7fdde340] Could not find a valid device
  
  [h264_v4l2m2m @ 0x7fdde340] can't configure encoder
  
  Could not open codec 'h264_v4l2m2m': Unspecified error
  
  Starting

  When I try the ’M’,’P’,’4’,’V’ format I get the error :

  Initializing Video Recording to save Video file here:  "/tmp/Garage.mp4"
  
  OpenCV: FFMPEG: tag 0x5634504d/'MP4V' is not supported with codec id 13 and format 'mp4 / MP4 (MPEG-4 Part 14)'
  
  OpenCV: FFMPEG: fallback to use tag 0x7634706d/'mp4v'
  
  Starting

  When I try the ’A’,’V’,’C’,’1’ format I get the error :

  Initializing Video Recording to save Video file here:  "/tmp/Garage.mp4"
  
  OpenCV: FFMPEG: tag 0x31435641/'AVC1' is not supported with codec id 28 and format 'mp4 / MP4 (MPEG-4 Part 14)'
  
  OpenCV: FFMPEG: fallback to use tag 0x31637661/'avc1'
  
  [h264_v4l2m2m @ 0x810f5f50] Could not find a valid device
  
  [h264_v4l2m2m @ 0x810f5f50] can't configure encoder
  
  Could not open codec 'h264_v4l2m2m': Unspecified error
  
  Starting

  When I try the ’D’,’I’,’V’,’X’ format I get the error :

  Initializing Video Recording to save Video file here:  "/tmp/Garage.mp4"
  
  OpenCV: FFMPEG: tag 0x58564944/'DIVX' is not supported with codec id 13 and format 'mp4 / MP4 (MPEG-4 Part 14)'
  
  OpenCV: FFMPEG: fallback to use tag 0x7634706d/'mp4v'
  
  Starting

  When I try the 0x21 format I get the error :

  Initializing Video Recording to save Video file here:  "/tmp/Garage.mp4"
  
  OpenCV: FFMPEG: tag 0x00000021/'!???' is not found (format 'mp4 / MP4 (MPEG-4 Part 14)')'
  
  Starting

  Here is my complete class which shows all tried formats :

      #include "downloader.h"
  
  
  
  Downloader::Downloader(QString url, QString destinationFile) : downloadUrl(url) , destinationFileName(destinationFile)
  
  {
  
  
  
      didInitializeVideoWriter = false;
  
  
  
      qDebug() << "Initialized Downloader...";
  
  
  
  }
  
  
  
  Downloader::~Downloader() {
  
  
  
      videoRecorder->release();
  
      delete videoRecorder;
  
  
  
  }
  
  
  
  void Downloader::doDownload()
  
  {
  
      networkManager = new QNetworkAccessManager(this);
  
  
  
      connect(networkManager, SIGNAL(finished(QNetworkReply*)),
  
              this, SLOT(replyFinished(QNetworkReply*)));
  
  
  
      networkManager->get(QNetworkRequest(QUrl(downloadUrl)));
  
  }
  
  
  
  void Downloader::writeFrame(cv::Mat frame) {
  
  
  
      QMutexLocker locker(&videoFrameMutex);
  
  
  
      videoRecorder->write(frame);
  
  
  
  }
  
  
  
  void Downloader::replyFinished(QNetworkReply *reply)
  
  {
  
  
  
      if(reply->error())
  
      {
  
          qDebug() << "ERROR!";
  
          qDebug() << reply->errorString();
  
      }
  
      else
  
      {
  
          //qDebug() << reply->header(QNetworkRequest::ContentTypeHeader).toString();
  
          //qDebug() << reply->header(QNetworkRequest::LastModifiedHeader).toDateTime().toString();
  
          //qDebug() << reply->header(QNetworkRequest::ContentLengthHeader).toULongLong();
  
          qDebug() << reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
  
          qDebug() << reply->attribute(QNetworkRequest::HttpReasonPhraseAttribute).toString();
  
  
  
          QString tempFileName = destinationFileName;
  
          QString jpegTempFilename = QString("%1").arg(tempFileName.replace("mp4","jpeg"));
  
  
  
          qDebug() << "Overwriting: " << jpegTempFilename;
  
          QFile *file = new QFile(jpegTempFilename);
  
          if(file->open(QFile::WriteOnly))
  
          {
  
              file->write(reply->readAll());
  
              file->flush();
  
              file->close();
  
          }
  
          delete file;
  
  
  
          cv::Mat frame = imread(jpegTempFilename.toStdString(), CV_LOAD_IMAGE_COLOR);   // CV_LOAD_IMAGE_COLOR (>0) loads the image in the BGR format
  
          cv::cvtColor(frame,frame,CV_BGR2RGB);
  
  
  
          // Now lazy load the recorder
  
          if ( !didInitializeVideoWriter ) {
  
  
  
              cv::Size frameSize = frame.size();
  
  
  
              qDebug() << "Initializing Video Recording to save Video file here: " << destinationFileName;
  
  
  
              std::string filename = destinationFileName.toStdString();
  
              //int fcc =   CV_FOURCC('M','J','P','G');
  
              int fcc =   CV_FOURCC('X','2','6','4');
  
              //int fcc = CV_FOURCC('X','V','I','D');
  
              //int fcc = CV_FOURCC('M','P','E','G');
  
              //int fcc = CV_FOURCC('H','2','6','4');
  
              //int fcc = CV_FOURCC('M','P','4','V');
  
              //int fcc = CV_FOURCC('A','V','C','1');
  
              //int fcc = CV_FOURCC('D','I','V','X');
  
              //int fcc = 0x21;
  
              //int fcc = 0x00000021;
  
              int fps =   1;
  
              videoRecorder = new cv::VideoWriter(filename,fcc,fps,frameSize);
  
  
  
              qDebug() << "Starting";
  
              frameCounter = 1;
  
              performanceTimer.start();
  
  
  
              didInitializeVideoWriter = true;
  
  
  
          }
  
  
  
          cv::putText(frame,"[REC]",cv::Point(50,50),5,1,cv::Scalar(0,0,225));
  
  
  
          QFuture<void> backgroundRun = QtConcurrent::run(this, &amp;Downloader::writeFrame, frame);
  
          //backgroundRun.waitForFinished();
  
  
  
      }
  
  
  
      reply->deleteLater();
  
  
  
      qDebug() &lt;&lt; "RequestTimer: " &lt;&lt; performanceTimer.elapsed() &lt;&lt; frameCounter;
  
  
  
      // Requests Again
  
      networkManager->get(QNetworkRequest(QUrl(downloadUrl)));
  
  
  
      frameCounter++;
  
  
  
      performanceTimer.restart();
  
  
  
  
  
  }
  
  </void>

  Update - I tried ’a’,’v’,’c’,’1’ and unfortunately that also does not work :

  Initializing Video Recording to save Video file here:  "/tmp/Garage.mp4"
  
  [h264_v4l2m2m @ 0x810f6aa0] Could not find a valid device
  
  [h264_v4l2m2m @ 0x810f6aa0] can't configure encoder
  
  Could not open codec 'h264_v4l2m2m': Unspecified error
  
  
  
  (qt-downloader:6234): GStreamer-CRITICAL **: gst_element_make_from_uri: assertion 'gst_uri_is_valid (uri)' failed
  
  OpenCV Error: Unspecified error (GStreamer: cannot link elements
  
  ) in CvVideoWriter_GStreamer::open, file /media/usb/opencv/modules/videoio/src/cap_gstreamer.cpp, line 1635
  
  VIDEOIO(cvCreateVideoWriter_GStreamer (filename, fourcc, fps, frameSize, is_color)): raised OpenCV exception:
  
  
  
  /media/usb/opencv/modules/videoio/src/cap_gstreamer.cpp:1635: error: (-2) GStreamer: cannot link elements
  
   in function CvVideoWriter_GStreamer::open

  When I try the X264 FOURCC, the mp4 file is 48 bytes and never grows :

  Initializing Video Recording to save Video file here:  "/tmp/Garage.mp4"
  
  OpenCV: FFMPEG: tag 0x34363258/'X264' is not supported with codec id 27 and format 'mp4 / MP4 (MPEG-4 Part 14)'
  
  OpenCV: FFMPEG: fallback to use tag 0x31637661/'avc1'

  Static Size :

  debian@BeagleBoard-X15:/tmp$ ls -lrt Garage.*
  
  -rw-r--r-- 1 debian debian     48 Dec 24 21:13 Garage.mp4
  
  -rw-r--r-- 1 debian debian 100424 Dec 24 21:14 Garage.jpeg
  
  debian@BeagleBoard-X15:/tmp$ hexdump Garage.mp4 
  
  0000000 0000 2000 7466 7079 7369 6d6f 0000 0002
  
  0000010 7369 6d6f 7369 326f 7661 3163 706d 3134
  
  0000020 0000 0800 7266 6565 0000 0000 646d 7461
  
  0000030

  Here is my ffmpeg build conf :

  debian@BeagleBoard-X15:/tmp$ ffmpeg -buildconf
  
  ffmpeg version N-89524-g74f408cc8e Copyright (c) 2000-2017 the FFmpeg developers
  
    built with gcc 6.3.0 (Debian 6.3.0-18) 20170516
  
    configuration: --enable-gpl --enable-libx264 --enable-pthreads --enable-static --extra-cflags=-I./x264/include --extra-ldflags=-L./x264/lib --extra-libs=-ldl
  
    libavutil      56.  6.100 / 56.  6.100
  
    libavcodec     58.  8.100 / 58.  8.100
  
    libavformat    58.  3.100 / 58.  3.100
  
    libavdevice    58.  0.100 / 58.  0.100
  
    libavfilter     7.  7.100 /  7.  7.100
  
    libswscale      5.  0.101 /  5.  0.101
  
    libswresample   3.  0.101 /  3.  0.101
  
    libpostproc    55.  0.100 / 55.  0.100
  
  
  
    configuration:
  
      --enable-gpl
  
      --enable-libx264
  
      --enable-pthreads
  
      --enable-static
  
      --extra-cflags=-I./x264/include
  
      --extra-ldflags=-L./x264/lib
  
      --extra-libs=-ldl

• Is this the best way to decrease the number of failures when downloading m3u8 ?

  26 juillet 2022, par zackchess1

  I have a bunch of m3u8 links that I am trying to download.

  


  When I use ffmpeg, I get an average of 8/10 videos. The remaining 2 videos simply don't download. I use this command :

  


  ffmpeg -i http://.../playlist.m3u8 -c copy -bsf:a aac_adtstoasc output.mp4

  


  I have seen suggestions to use yt-dlp and aria2c to reduce the number of failures. Do either of these actually affect failure rates ?

  


  Would you suggest using :

  


  yt-dlp M3U8LINK

  


  OR

  


  yt-dlp --downloader aria2c M3U8LINK

  


  IF NOT, WHAT COMMAND DECREASES THE NUMBER OF FAILURES ? Thanks.

  


• Want to convert my 16:9 size MKV video to 4:3 size AVI video file

  19 septembre 2012, par Bimal Rekhadiya

  I have a video in MKV format and it's size is 720x304 (16:9 ratio) size video.

  I want to convert it to AVi format (using xvid video codec). The output file size should be 480x360 (4:3 ratio) and also want to keep the original (16:9) ratio so it should be cinemascope (black areas at top and bottom).

  I am on Ubuntu linux OS so I can use mencoder, avconv(ffmpeg) or any tool that work on Linux.

  I am trying this command :

  avconv -i sample.mkv -vcodec libxvid -r 25 -b 1200 -aspect 4:3 -q 1 t.avi

  But the problem is that the video is stretched to 4:3 and I want to keep original video's ratio and want to add black boxes at top and bottom so it will look cinemascope.

  Please provide me command to do this.