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• Merge individual frame to video file using Opencv

  18 août 2022, par Rohit

  I am trying to stack a individual frame to a video file using Opencv. I want to combine two different code together to make the individual frame.
Following code help me extract the individual frame,

  


  fourcc = cv2.VideoWriter_fourcc(*'mp4v')
out = cv2.VideoWriter('file_data.mp4',fourcc,20 (1920,1080),False)
while True:
    ret, frame=cap.read()
    mask = object_detector.apply(frame)
    _, mask  = cv2.threshold(mask,254,255,cv2.THRESH_BINARY)       
    contours,_ = cv2.findContours(mask, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
    res = cv2.bitwise_and(frame,frame,mask=mask)
    for cnt in contours:
        area = cv2.contourArea(cnt)
        if area>1000:   
            #print("Area of contour:", area)
            cv2.drawContours(frame, [cnt], -1, (0,255,0),2)
            cv2.imwrite("file%d.jpg"%count, frame)
            out.write(frame)
    if cv2.waitKey(1) and 0xFF == ord('q'):
        break


  


  I tried storing the individual frame in array, but it didn't work. It doesn't show any error, but pc crash.

  


  


  fps = 20,
,width = 1920
,height = 1080

  


  


• Strange error with ffmpeg and unoconv in python script

  27 mai 2015, par Avery Ripoll Crocker

  I am creating a python script that can be used by other people to convert files. However when I use this script I keep getting a weird error when I run the subprocess for unoconv, this error is :

  Traceback (most recent call last):
  
    File "conversion.py", line 15, in <module>
  
      check_call(["unoconv", "-f", Fileextension, filename])
  
    File "/usr/lib/python2.7/subprocess.py", line 540, in check_call
  
      raise CalledProcessError(retcode, cmd)
  
  subprocess.CalledProcessError: Command '['unoconv', '-f', '.pdf', 'journal.doc']' returned non-zero exit status 1
  
  </module>

  I have looked through various resources for this, but the one answer I have been receiving is that I must have set up the unoconv line incorrectly. I have checked several times that the code is correct, and it is. The other peculiar thing is that my code for ffmpeg works. Does anybody have an idea as to why this happens.

  Here is my program :

  print "If at any point you wish to quit the program hit Ctrl + C"
  
  
  
  filetype = raw_input("What kind of file would you like to convert? Audio, Image, Video or Document: ")
  
  
  
  if filetype == "Document":
  
     path = raw_input("Please drag and drop the directory in which the file is stored into the terminal:")
  
     os.chdir(path[1:-2])
  
     filename = raw_input("Please enter the name of the file you would like to convert, including the file-type. e.g. test.txt, however please do make sure that the file-name does not have any spaces:")
  
     Fileextension = raw_input("What filetype would you like the program to convert your file to. E.g. .txt: ")
  
     from subprocess import check_call
  
     check_call(["unoconv", "-f", Fileextension, filename])
  
  
  
  elif filetype == "Audio":
  
     path = raw_input("Please drag and drop the directory in which the file is stored into the terminal:")
  
     os.chdir(path[1:-2])
  
     filename = raw_input("Please enter the name of the file you would like to convert, including the file-type. e.g. test.txt, however please do make sure that the file-name does not have any spaces:")
  
     Fileextension = raw_input("What filetype would you like the program to convert your file to. E.g. .mp3: ")
  
     body, ext = os.path.splitext("filename")
  
     from subprocess import check_call
  
     check_call(["ffmpeg" ,"-i", filename, body + Fileextension])
  
  
  
  elif filetype == "Video":
  
     path = raw_input("Please drag and drop the directory in which the file is stored into the terminal:")
  
     os.chdir(path[1:-2])
  
     filename = raw_input("Please enter the name of the file you would like to convert, including the file-type. e.g. test.txt, however please do make sure that the file-name does not have any spaces:")
  
     Fileextension = raw_input("What filetype would you like the program to convert your file to. E.g. .mp4: ")
  
     body, ext = os.path.splitext("filename")
  
     from subprocess import check_call
  
     check_call(["ffmpeg" ,"-i", filename, body + Fileextension])
  
  
  
  elif filetype == "Image":
  
     path = raw_input("Please drag and drop the directory in which the file is stored into the terminal:")
  
     os.chdir(path[1:-2])
  
     filename = raw_input("Please enter the name of the file you would like to convert, including the file-type. e.g. test.txt, however please do make sure that the file-name does not have any spaces:")
  
     Fileextension = raw_input("What filetype would you like the program to convert your file to. E.g. .Jpeg: ")
  
     body, ext = os.path.splitext("filename")
  
     from subprocess import check_call    
  
     check_call(["ffmpeg" ,"-i", filename, body + Fileextension])

• Decoding H.264 individual nal units

  24 septembre 2018, par madprogrammer2015

  I am currently sending individual NAL units across a network. These NAL units are generated by x264. Now is it possible to feed these NAL units individually into avcodec_decode_video2 ?

  Or do I have to concatenate the nal units until they represent the same frame ? If thats the case then how is that done ?

  I have also read that I might be able to receive the SPS and PPS packets. Then wait for at least one packet, and attempt to decode. Is this correct ?

  Any advice that can be offered would be greatly appreciated