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• What could be serve as a nullptr in cython wrapper for C++ uint8_t multidimensional array ?

  20 juillet 2020, par yose93

  I've stuck with solving of one problem. I have to fill C++ structure with yuv420p frame data in my cython wrapper :

  


  #define FR_PLANE_COUNT_MAX 8

typedef struct fr_frame_s {
    int format = 0;

    int width = 0;
    int height = 0;

    uint8_t* data[FR_PLANE_COUNT_MAX];

    int     stride[FR_PLANE_COUNT_MAX];

    int     size[FR_PLANE_COUNT_MAX];

    long long time = 0;

} fr_frame_t;




  


  Where data is just a multidimensional array with length of 8. In this array first three elements to be y, u and v byte multidimensional arrays, and the rest are just nullptr values. The next chunk of code which I need to implement on pure python just to fill the structure with according data of the above structure itself :

  


  bool VideoCapture::ConvertFrame(const AVFrame *src, fr_frame_t &dst)
{
    if(src != NULL)
    {
        for (size_t i = 0; i < FR_PLANE_COUNT_MAX; ++i)
        {
            if (src->data[i] != nullptr)
            {
                const int line = src->linesize[i];
                const int size = i == 0 ? line * src->height : int(line * (src->height / 2.0));
                dst.data[i] = (uint8_t*)malloc(size);
                memcpy(dst.data[i], src->data[i], size);

                //dst.data[i] = src->data[i];
                dst.size[i] = size;
                dst.stride[i] = src->linesize[i];
            }else{
                dst.data[i] = nullptr;
                dst.size[i] = 0;
                dst.stride[i] = 0;
            }
        }



  


  Here all the values after y, u, v arrays must be just of nullptr as it seems. So, what I can use as nullptr to fill np.ndarray after y, u, v.

  


  And my python code :

  


  def _get_read_frames(
        self,
        video: pathlib.PosixPath,
    ) -> Generator[Tuple[Union[teyefr.MetadataImage, float]], None, None]:
        """Video frames reader."""
        self._cap = cv2.VideoCapture(str(video))
        self._total_frames = self._cap.get(cv2.CAP_PROP_FRAME_COUNT)
        self._fps = math.ceil(self._cap.get(cv2.CAP_PROP_FPS))
        self._duration = self._total_frames / self._fps

        while(self._cap.isOpened()):
            _, frame = self._cap.read()

            if frame is None:
                break
            
            yuv420_frame = cv2.cvtColor(frame, cv2.COLOR_BGR2YUV)

            self._process_yuv420_frame(yuv420_frame)

        self._cap.release()
    
    def _process_yuv420_frame(self, yuv420_frame: np.ndarray) -> None:
        """To fill `self._fr_frames` list.

        Splits already converted frame into 3-channels y, u, v
        and takes all required data to fill `FRFrame` and push it.
        """
        data = np.array([])
        stride = np.array([])
        size = np.array([])
        frame_data = {}.fromkeys(FRFrame.__dataclass_fields__.keys())

        channels = (y, u, v) = cv2.split(yuv420_frame)

        for i in range(FR_PLANE_COUNT_MAX):
            if i < len(channels):
                np.concatenate(data, channels[i])
            else:
                np.concatenate(data, np.array([]))
            
        frame_data['height'], frame_data['width'], _ = yuv420_frame.shape


  


  Please advise.

  


• C# process FFMPEG output from standard out (pipe) [duplicate]

  30 janvier 2018, par Alexander Streckov

  This question already has an answer here :

  • Getting Binary Data from StandardOutput
    
    1 answer
    
  • Capturing binary output from Process.StandardOutput
    
    3 answers
    

  I want to extract the current image from the FFMPEG standard output and show it on a C# form. The stream source itself is a h264 raw data which converted into image and piped to the standard output. Here is my code, but I have no idea how to process the output (maybe MemoryStream) :

  public Process ffproc = new Process();
  
  private void xxxFFplay()
  
  {
  
      ffproc.StartInfo.FileName = "ffmpeg.exe";
  
      ffproc.StartInfo.Arguments = "-y -i udp://127.0.0.1:8888/ -q:v 1 -huffman optimal -update 1 -f mjpeg -";
  
  
  
      ffproc.StartInfo.CreateNoWindow = true;
  
      ffproc.StartInfo.RedirectStandardOutput = true;
  
      ffproc.StartInfo.UseShellExecute = false;
  
  
  
      ffproc.EnableRaisingEvents = true;
  
      ffproc.OutputDataReceived += (o, e) => Debug.WriteLine(e.Data ?? "NULL", "ffplay");
  
      fproc.ErrorDataReceived += (o, e) => Debug.WriteLine(e.Data ?? "NULL", "ffplay");
  
      ffproc.Exited += (o, e) => Debug.WriteLine("Exited", "ffplay");
  
      ffproc.Start();
  
  
  
      worker = new BackgroundWorker();
  
      worker.DoWork += worker_DoWork;
  
      worker.WorkerReportsProgress = true;
  
      worker.ProgressChanged += worker_ProgressChanged;
  
      worker.RunWorkerAsync();
  
  }
  
  
  
  public void worker_DoWork(object sender, DoWorkEventArgs e)
  
  {
  
      try
  
      {
  
          var internalWorker = sender as BackgroundWorker;
  
          Process p = e.Argument as Process;
  
          buffer = new MemoryStream();
  
          bufferWriter = new BinaryWriter(buffer);
  
          using (var reader = new BinaryReader(p.StandardOutput.BaseStream))
  
          {
  
              while (true)
  
              {
  
                  bufferWriter.Write(1);
  
                  var img = (Bitmap)Image.FromStream(buffer);
  
                  pictureBox1.Image = img;
  
                  //get the jpg image
  
              }
  
           }
  
       }
  
       catch (Exception ex)
  
       {
  
             // Log the error, continue processing the live stream
  
       }
  
   }

  Any help would be appreciated !

• Moviepy : subclip fails when iterating through CSV

  5 mai 2016, par user3316291

  I am trying to randomize the order of video clips based on timing from a CSV file and then reassemble the randomized clips into a single video. However, I am receiving an error in the loop that iterates through each clip timing to create the subclip.

  Here is what my CSV looks like :

  00:00:32.18,00:00:52.10,1
  
  00:00:52.11,00:00:56.09,2
  
  00:00:56.10,00:00:58.15,3
  
  00:00:58.16,00:01:05.16,4
  
  00:01:05.17,00:01:16.04,5

  column 1 is clip onset
  column 2 is clip offset
  column 3 is scene number that I use to randomize

  Here is my code :

  import os
  
  import csv
  
  import numpy as np
  
  from moviepy.editor import *
  
  
  
  f = open('SceneCuts.csv')
  
  csv_f = csv.reader(f)
  
  
  
  scenes = []
  
  ons = []
  
  offs = []
  
  for row in csv_f:
  
      ons.append(row[0])
  
      offs.append(row[1])
  
      scenes.append(row[2])
  
  
  
  r_scene = scenes
  
  np.random.seed(1000)
  
  np.random.shuffle(r_scene)
  
  r_scene = map(int, r_scene)
  
  
  
  clip = VideoFileClip("FullVideo.m4v")
  
  
  
  temp = []
  
  for row in r_scene:
  
      print(row)
  
      temp.append(clip.subclip(ons[row-1], offs[row-1]))
  
  
  
  catclip = concatenate_videoclips(temp)
  
  catclip_resize = catclip.resize((1024,576))
  
  catclip_resize.write_videofile("RandomVideo.mp4")

  Here is the output, error occurs at line 29 (temp.append)

  File "/Users/Dustin/anaconda/lib/python2.7/site-packages/moviepy/video/io/ffmpeg_reader.py", line 87, in initialize
  
  self.proc = sp.Popen(cmd, **popen_params)
  
  
  
  File "/Users/Dustin/anaconda/lib/python2.7/subprocess.py", line 710, in __init__
  
  errread, errwrite)
  
  
  
  File "/Users/Dustin/anaconda/lib/python2.7/subprocess.py", line 1316, in _execute_child
  
  data = _eintr_retry_call(os.read, errpipe_read, 1048576)
  
  
  
  File "/Users/Dustin/anaconda/lib/python2.7/subprocess.py", line 476, in _eintr_retry_call
  
  return func(*args)
  
  
  
  OSError: [Errno 22] Invalid argument

  Based on my research, it appears to be something regarding child processes and subprocess.Popen, but I can’t figure it out. Thanks !

  EDIT to add new information :
  I have been running the above script in Spyder (anaconda) and receiving the above errors. However, when I run from a terminal or sublime (cmd+b), the code "works". It runs and I do not get the above error, however, the resulting video file is a mess. There are multiple conflicting audio tracks that shouldn’t be there. I am not sure what is going on in Spyder, but I’d love to know. Also, I still need to fix the audio problem.