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• How can i merge two videos using ffmpeg ?

  10 novembre 2017, par hasib prince

  I am using writingminds:FFmpegAndroid:0.3.2 library.and facing this permission denied issue.

  D/Video merging :: progress: /storage/emulated/0/DCIM/Camera/VID_20171109_070248.mp4: Permission denied

  11-10 17:35:09.905 10592-10592/com.example.hasib.vjoiner D/Video merging: : failure : ffmpeg version n3.0.1 Copyright (c) 2000-2016 the FFmpeg developers
  built with gcc 4.8 (GCC)

                                                                           libavutil      55. 17.103 / 55. 17.103
  
                                                                           libavcodec     57. 24.102 / 57. 24.102
  
                                                                           libavformat    57. 25.100 / 57. 25.100
  
                                                                           libavdevice    57.  0.101 / 57.  0.101
  
                                                                           libavfilter     6. 31.100 /  6. 31.100
  
                                                                           libswscale      4.  0.100 /  4.  0.100
  
                                                                           libswresample   2.  0.101 /  2.  0.101
  
                                                                           libpostproc    54.  0.100 / 54.  0.100
  
                                                                         /storage/emulated/0/DCIM/Camera/VID_20171109_070248.mp4: Permission denied

  11-10 17:35:09.905 10592-10592/com.example.hasib.vjoiner D/Video merging: : finished

  and this is the command i was going to execute.

  String[] command = new String[]{"-y", "-i", videoPaths.get(0), "-i", videoPaths.get(1).toString(), "-strict", "experimental", "-filter_complex",
  
              "[0:v]scale=iw*min(1920/iw\\,1080/ih):ih*min(1920/iw\\,1080/ih), pad=1920:1080:(1920-iw*min(1920/iw\\,1080/ih))/2:(1080-ih*min(1920/iw\\,1080/ih))/2,setsar=1:1[v0];[1:v] scale=iw*min(1920/iw\\,1080/ih):ih*min(1920/iw\\,1080/ih), pad=1920:1080:(1920-iw*min(1920/iw\\,1080/ih))/2:(1080-ih*min(1920/iw\\,1080/ih))/2,setsar=1:1[v1];[v0][0:a][v1][1:a] concat=n=2:v=1:a=1",
  
              "-ab", "48000", "-ac", "2", "-ar", "22050", "-s", "1920x1080", "-vcodec", "libx264", "-crf", "27", "-q", "4", "-preset", "ultrafast", outputPath + "/output.mp4"};

• cv::cudacodec::VideoReader unable to Play rtsp stream

  22 février 2018, par Pawan

  System information

  • OpenCV => 3.3.0
  • Operating System / Platform => Ubuntu 16.04, x86_64
  • Compiler => gcc version 5.4.1 20160904
  • Cuda => 8.0
  • Nvidia card => GTX 1080 Ti
  • ffmpeg details
    • libavutil 55. 74.100 / 55. 74.100
    • libavcodec 57.103.100 / 57.103.100
    • libavformat 57. 77.100 / 57. 77.100
    • libavdevice 57. 7.101 / 57. 7.101
    • libavfilter 6.100.100 / 6.100.100
    • libswscale 4. 7.103 / 4. 7.103
    • libswresample 2. 8.100 / 2. 8.100

  Detailed description

  i am trying to play a rtsp stream using cudacodec::VideoReader

  Rtsp Stream Details ( from vlc )

  

  this stream plays fine in vlc and cv::VideoCapture but when i try to play it in cudacodec::VideoReader i get a error saying :

  OpenCV Error: Gpu API call (CUDA_ERROR_FILE_NOT_FOUND [Code = 301]) in CuvidVideoSource, file /home/deep/Development/libraries/opencv/opencv/modules/cudacodec/src/cuvid_video_source.cpp, line 66

  OpenCV Error: Assertion failed (init_MediaStream_FFMPEG()) in FFmpegVideoSource, file /home/deep/Development/libraries/opencv/opencv/modules/cudacodec/src/ffmpeg_video_source.cpp, line 101

  Steps to reproduce

  #include <iostream>
  
  #include "opencv2/opencv_modules.hpp"
  
  
  
  #if defined(HAVE_OPENCV_CUDACODEC)
  
  
  
  #include <opencv2></opencv2>core.hpp>
  
  #include <opencv2></opencv2>cudacodec.hpp>
  
  #include <opencv2></opencv2>highgui.hpp>
  
  
  
  int main(int argc, const char* argv[])
  
  {
  
      const std::string fname = "rtsp://admin:admin@192.168.1.13/media/video2";
  
  
  
      cv::namedWindow("GPU", cv::WINDOW_NORMAL);
  
  
  
      cv::cuda::GpuMat d_frame;
  
      cv::Ptr d_reader = cv::cudacodec::createVideoReader(fname);
  
  
  
      for (;;)
  
      {
  
  
  
          if (!d_reader->nextFrame(d_frame))
  
              break;
  
  
  
          cv::Mat frame;
  
          d_frame.download(frame);
  
          cv::imshow("GPU", frame);
  
  
  
          if (cv::waitKey(3) > 0)
  
              break;
  
      }
  
      return 0;
  
  }
  
  
  
  #else
  
  int main()
  
  {
  
      std::cout &lt;&lt; "OpenCV was built without CUDA Video decoding support\n" &lt;&lt; std::endl;
  
      return 0;
  
  }
  
  #endif
  
  </iostream>

  I tried debugging it using GDB and saw that in ffmpeg_video_source.cpp bool init_MediaStream_FFMPEG() directly returns without checking the if condition.

  GDB output

  cv::cudacodec::detail::FFmpegVideoSource::FFmpegVideoSource 
  
  (this=0x402a20 <_start>, fname=...) at /home/deep/Development/libraries/opencv/opencv/modules/cudacodec/src/ffmpeg_video_source.cpp:98
  
  98      cv::cudacodec::detail::FFmpegVideoSource::FFmpegVideoSource(const String& fname) :
  
  (gdb) n
  
  99          stream_(0)
  
  (gdb) n
  
  101         CV_Assert( init_MediaStream_FFMPEG() );
  
  (gdb) s
  
  (anonymous namespace)::init_MediaStream_FFMPEG () at /home/deep/Development/libraries/opencv/opencv/modules/cudacodec/src/ffmpeg_video_source.cpp:94
  
  94              return initialized;
  
  (gdb) display initialized
  
  4: initialized = false
  
  (gdb) s
  
  95          }

  UPDATE :

  I have solved the problem. solution link

• ffmpeg concatenating videos of different fps while keeping the total length not changed

  23 novembre 2017, par A_Matar

  I wanna pad an mp4 video stream with another video clip of a static image that I created using :

  def generate_white_vid (duration):
  
      output_filename = os.path.join(p_path,'white_vid_'+" 0:.2f}".format(duration)+'.mp4')
  
      ffmpeg_create_vid_from_static_img = 'ffmpeg -loop 1 -i /path/WhiteBackground.jpg -c:v libx264 -t %f -pix_fmt yuv420p -vf scale=1920:1080 %s' % (duration, output_filename)
  
      p = subprocess.Popen(ffmpeg_create_vid_from_static_img, shell=True)
  
      p.communicate()
  
      return output_filename

  I use the following to concatenate :

  def concat_vids(clip_paths):
  
      filenames_txt = open('clips_to_join.txt','w')
  
      for clip in clip_paths:
  
          filenames_txt.write ('file \''+ clip+'\'\n')
  
      filenames_txt.close()
  
      output_filename = clip_paths[0].split('.', 2)[0]
  
      output_file_path = os.path.join(root_path, output_filename+'-padded.mp4')
  
      # join the clips
  
      ffmpeg_command = ["ffmpeg", "-f", "concat", "-safe", "0", "-i", "clips_to_join.txt", "-codec", "copy", output_file_path] # output_filename = ch0X-start_time-end_time
  
      p = subprocess.Popen(ffmpeg_command)
  
      p.communicate() # wait till the subprocess finishes. You can send commands to process as well.
  
      return output_file_path

  When I check the length of the resulting video after concatenation, I find that it is not equal to the sum of the two segments that I concatenated, and sometimes it is even less by some seconds !!

  Here is how I get the video length in seconds :

  def ffmpeg_len(vid_path):
  
      '''
  
      Returns length in seconds using ffmpeg
  
      '''
  
      ffmpeg_get_mediafile_length = ['sh', '-c', 'ffmpeg -i "$1" 2>&1 | grep Duration', '_', vid_path]
  
      p = subprocess.Popen(ffmpeg_get_mediafile_length, stdout=subprocess.PIPE, stderr=subprocess.PIPE)    
  
      output, err = p.communicate()
  
      length_regexp = 'Duration: (\d{2}):(\d{2}):(\d{2})(\.\d+),'
  
      re_length = re.compile(length_regexp)
  
      matches = re_length.search(output)
  
      if matches:
  
          video_length = int(matches.group(1)) * 3600 + \
  
                          int(matches.group(2)) * 60 + \
  
                          int(matches.group(3)) + float(matches.group(4))
  
          return video_length
  
      else:
  
          print("Can't determine video length.")
  
          print err
  
          raise SystemExit

  My guess is that maybe the concatenation unifies the fps rate for the all the clips to be joined, if this is the case, how to prevent this from happening ? How can I get a video of the desired length exactly.

  Maybe it worth mentioning that the video to padded is very short 0.42 second, the original video is 210.58 and the resultant video is 210.56 !

  I have verified that ffmpeg does generate the desired padding region and it is of the desired length 0.42 I got a 0.43 segment when I forced 30 fps but it is okay.