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• OpenCV3.3.1 fails to read a video

  1er janvier 2018, par Kasparov92

  Here is the code I use

  file_name = 'movie.avi'
  
  cap = cv2.VideoCapture(file_name)
  
  
  
  success, frame = cap.read()
  
  
  
  i = 0
  
  
  
  while success:
  
      i +=1
  
      success, frame = cap.read()
  
  
  
  print "Frames successfully read:", i

  And I am getting this error :

  Unable to stop the stream: Inappropriate ioctl for device
  
  
  
  (python:139873): GLib-GObject-CRITICAL **: g_object_set: assertion 'G_IS_OBJECT (object)' failed
  
      Frames successfully read: 0

  On this particular video, it fails to read ! I tried the same code on other videos and they work fine. I also tried the same piece of code with another laptop (same operating system : Ubuntu 16.04) and it works.

  Is it a codec issue ? if so why other videos could be loaded and read successfully ?

  EDIT 1 :

  I recompiled opencv using -DWITH_LIBV4L=ON after sudo apt-get install libv4l-dev and Now I am getting this error :

  Failed to query video capabilities: Inappropriate ioctl for device
  
  libv4l2: error getting capabilities: Inappropriate ioctl for device
  
  VIDEOIO ERROR: V4L: device /root/datasets/UCF-101/TableTennisShot/v_TableTennisShot_g22_c02.avi: Unable to query number of channels
  
  
  
  (python:173084): GLib-GObject-CRITICAL **: g_object_set: assertion 'G_IS_OBJECT (object)' failed

• Why AVCodecContext extradata is NULL ?

  21 janvier 2016, par user3215358

  I am trying to decode h264 video using ffmpeg and stagefright library. I’m using this example.

  The example shows how to decode mp4 files, but i want to decode only h264 video.

  Here is piece of my code..

      AVFormatSource::AVFormatSource(const char *videoPath) 
  
      {
  
          av_register_all();
  
  
  
          mDataSource = avformat_alloc_context();
  
          avformat_open_input(&mDataSource, videoPath, NULL, NULL);
  
          for (int i = 0; i < mDataSource->nb_streams; i++) 
  
          {
  
              if (mDataSource->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) 
  
              {
  
                  mVideoIndex = i;
  
                  break;
  
              }
  
          }
  
          mVideoTrack = mDataSource->streams[mVideoIndex]->codec;
  
  
  
          size_t bufferSize = (mVideoTrack->width * mVideoTrack->height * 3) / 2;
  
          mGroup.add_buffer(new MediaBuffer(bufferSize));
  
          mFormat = new MetaData;
  
  
  
          switch (mVideoTrack->codec_id == CODEC_ID_H264) 
  
          {
  
              mConverter = av_bitstream_filter_init("h264_mp4toannexb");
  
              mFormat->setCString(kKeyMIMEType, MEDIA_MIMETYPE_VIDEO_AVC);
  
              if (mVideoTrack->extradata[0] == 1) //SIGSEGV Here
  
              {
  
                  mFormat->setCString(kKeyMIMEType, MEDIA_MIMETYPE_VIDEO_AVC);
  
                  mFormat->setData(kKeyAVCC, kTypeAVCC, mVideoTrack->extradata,
  
                                   mVideoTrack->extradata_size);
  
              }
  
           }
  
  
  
          mFormat->setInt32(kKeyWidth, mVideoTrack->width);
  
          mFormat->setInt32(kKeyHeight, mVideoTrack->height);
  
      }

  mVideoTrack->extradata is NULL. What i’m doing wrong ?? My question is, what should be in mVideoTrack->extradata for kKeyAVCC ??

  Please help me, I need Your help.
  Thanks in advance.

• Why does ffmpeg stop recording at midnight ?

  22 septembre 2019, par peter

  I have a shellscript like this under Kubuntu 19.10,

  #!/bin/bash
  
  
  
  while true
  
  do
  
      FILE=/media/petermc/Security5/Camera2/Camera2_.mp4  
  
      FILE=${FILE%.*}`date +%Y-%m-%d_%H-%M-%S-%N`.${FILE#*.}
  
      echo $FILE
  
  
  
      ffmpeg -rtsp_transport tcp -t 00:15:00 -i rtsp://*user*:*password*@192.168.1.60:554/ch02/0 -c copy -map 0 $FILE
  
  done

  It records files like this,

  Camera2_2019-09-21_23-36-57-874602376.mp4
  
  Camera2_2019-09-21_23-51-57-876639147.mp4

  Basically recording 15 minutes at a time from the RTSP feed, then starting a new file.

  However it stops working at midnight, the last few lines from the log file are this,

  frame= 3987 fps= 13 q=-1.0 size=  117760kB time=00:05:06.51 bitrate=3147.3kbits/s speed=1.01x    
  
  frame= 3994 fps= 13 q=-1.0 size=  118016kB time=00:05:07.07 bitrate=3148.4kbits/s speed=1.01x    
  
  frame= 4001 fps= 13 q=-1.0 size=  118016kB time=00:05:07.59 bitrate=3143.1kbits/s speed=1.01x    
  
  frame= 4008 fps= 13 q=-1.0 size=  118272kB time=00:05:08.11 bitrate=3144.6kbits/s speed=1.01x 

  So there doesn’t seem to be any error, it stops recording at 5 minutes into the last file with no error.

  Another piece of information is that I have 6 cameras, and 4 stopped recording, the ones connected to a DVR. I have a couple of IP cameras and they kept recording.

  What could be the cause of this ? Plus, what else could I do to work around this or diagnose this ?

  UPDATE :

  I believe the issue is because the DVR has a maintenance setup to restart once at week at midnight. If this is what happened, is there any way I can configure ffmpeg to restart if it has lost the stream ?