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• OpenCV videocapture() not opening video file from hard disk

  8 janvier 2020, par Rossi Riccardo

  Despite being a lot of threads on the issue of open CV not being able to open videos i still can’t manage to solve it.

  I’m trying to open and extract frames using openCV with spyder (os : windows 10, python 3.7.4). As far as i know (provided the file path is correct) cv2.read returns a 0 if either the codec is unsupported (converted the video to H264 to be sure and also downloaded a test avi used to test out this very issue in an older post ) or if there is a problem with the ffmpeg dependency.

  Since i thought this was the source of the issue i added conda and phyton to the PATH with the SETX command and, after that, ended up copying ffmpeg dll and cv2 folders everywhere since i couldn’t understand well were i was supposed to paste it. Results is that i still can’t make it work and can’t even opt to try to make the frame extractor directly with ffmpeg since even that one gives me an error with a copypasted function from it’s site.

  Here is the code :

  import os 
  
  import ffmpeg
  
  
  
  
  
  def read_frame_as_jpeg(in_filename, frame_num):
  
      out, err = (
  
          ffmpeg
  
          .input(in_filename)
  
          .filter('select', 'gte(n,{})'.format(frame_num))
  
          .output('pipe:', vframes=1, format='image2', vcodec='mjpeg')
  
          .run(capture_stdout=True)
  
      )
  
  
  
  # Read the video from specified path 
  
  #cam = cv2.VideoCapture(r'C:\MY\folder\264H.mp4') 
  
  cam = cv2.VideoCapture(r'C:\Users\name\Downloads\drop.avi') 
  
  fps=60
  
  vid_start=371
  
  vid_end=377
  
  sens=20
  
  out_dir=r"C:\MY\folder"
  
  out_dir=out_dir+'\\'
  
  print(out_dir)
  
  
  
  stri="drop.avi"#even tried putting the fiel in the same directory, no change
  
  read_frame_as_jpeg(stri, 1)
  
  
  
  # frame 
  
  currentframe = 0
  
  
  
  while(True): 
  
  
  
      # reading from frame 
  
      ret,frame = cam.read()
  
  
  
      print(currentframe)
  
      if ret and currentframe>= (fps*vid_start)-sens and currentframe<= (fps*vid_end)+sens: 
  
          # if video is still left continue creating images 
  
          name = out_dir+ str(currentframe) + '.bmp'
  
          print ('Creating...' + name) 
  
  
  
          # writing the extracted images 
  
          cv2.imwrite(name, frame) 
  
  
  
          # increasing counter so that it will 
  
          # show how many frames are created 
  
          currentframe += 1
  
      else: 
  
          break
  
  
  
  # Release all space and windows once done 
  
  cam.release() 
  
  cv2.destroyAllWindows()  

  The ffpeg error that i get is

  [WinError 2] Impossible to find the specified file

  while on the other hand since videocapture returns a 0 it doesn’t even enter the loop so i get just a "0" print

• In FFmpeg, using -filter_complex, how can I overlay and blend at the same time ?

  5 mars 2014, par Kristian Boruff

  My code works to combine three videos, resize the videos to 1920X1080, resize the watermark to the correct size, and then overlays the watermark to the lower left hand side. Then converts to the intended codecs for Youtube.
  My question is how do I Blend at the same time using the -filter_complex workflow ?
  Currently, I have the following workflow that does everything but set the opacity

  ffmpeg -y -i fancy movie.mov -i logo.png -i in.mov -i out.mov -c:v libx264 -crf 18 -b:v 50000k -preset veryfast -tune film -profile:v high -x264opts cabac=1:keyint=16:bframes=2:keyint_min=15 -c:a libvo_aacenc -ab 128K -ar 48000 -filter_complex "[0:0] scale=1920X1080 [main]; [2:0] scale=1920X1080 [start]; [3:0] scale=1920X1080 [end]; [start] [2:1] [main] [0:1] [end] [3:1] concat=n=3:v=1:a=1 [prog]; [1:0] scale=480:90 [wm]; [prog] [wm] overlay=36:main_h-overlay_h-45" fart.mp4

  I'm trying to add "blend=all_opacity=0.7" in the last step so the watermark will screen against the background. If I just add

  [prog] [wm] overlay=36:main_h-overlay_h-45, blend=all_mode='overlay':all_opacity=0.7" fart.mp4

  I get the error, Cannot find a matching stream for unlabeled input pad 1 on filter Parsed_blend_6

  If I try a semicolon instead,

  [prog] [wm] overlay=36:main_h-overlay_h-45; blend=all_mode='overlay':all_opacity=0.7

  I get the error, Cannot find a matching stream for unlabeled input pad 0 on filter Parsed_blend_6 which makes me think that it's expecting something like [input 1] [input 2] blend command [output]. The problem is that I need it to overlay and blend.

  I tried simplifying the code to just test if the blend operation was working properly.

  ffmpeg -i test.mp4 -i logo.png -filter_complex "[0:0] scale=1920x1080 [wm]; [1:0] scale=1920x1080 [prog], [wm][prog] blend=all_mode='overlay':all_opacity=0.7" fart.mp4

  I got the error First input link top parameters (size 1920x1080, SAR 1:1) do not match the corresponding second input link bottom parameters (1920x1080, SAR 243:80)
  Failed to configure output pad on Parsed_blend_2

  So, in addition to the trouble with combining of filters, I'm also having an issue with resizing the watermark as FFMpeg sees it as a different aspect ratio than the other videos.

  This is my second day with FFmpeg, so any help would be appreciated.

  I'm currently working with FFMpeg version N-61061-gf34cceb

• In FFmpeg, using -filter_complex, how can I overlay and blend at the same time ?

  20 avril 2023, par Kristian Boruff

  My code works to combine three videos, resize the videos to 1920X1080, resize the watermark to the correct size, and then overlays the watermark to the lower left hand side. Then converts to the intended codecs for Youtube.
My question is how do I Blend at the same time using the -filter_complex workflow ?
Currently, I have the following workflow that does everything but set the opacity

  



  ffmpeg -y -i fancy movie.mov -i logo.png -i in.mov -i out.mov -c:v libx264 -crf 18 -b:v 50000k -preset veryfast -tune film -profile:v high -x264opts cabac=1:keyint=16:bframes=2:keyint_min=15 -c:a libvo_aacenc -ab 128K -ar 48000 -filter_complex "[0:0] scale=1920X1080 [main]; [2:0] scale=1920X1080 [start]; [3:0] scale=1920X1080 [end]; [start] [2:1] [main] [0:1] [end] [3:1] concat=n=3:v=1:a=1 [prog]; [1:0] scale=480:90 [wm]; [prog] [wm] overlay=36:main_h-overlay_h-45" fart.mp4


  



  I'm trying to add "blend=all_opacity=0.7" in the last step so the watermark will screen against the background. If I just add

  



  [prog] [wm] overlay=36:main_h-overlay_h-45, blend=all_mode='overlay':all_opacity=0.7" fart.mp4


  



  I get the error, Cannot find a matching stream for unlabeled input pad 1 on filter Parsed_blend_6

  



  If I try a semicolon instead,

  



  [prog] [wm] overlay=36:main_h-overlay_h-45; blend=all_mode='overlay':all_opacity=0.7


  



  I get the error, Cannot find a matching stream for unlabeled input pad 0 on filter Parsed_blend_6 which makes me think that it's expecting something like [input 1] [input 2] blend command [output]. The problem is that I need it to overlay and blend.

  



  I tried simplifying the code to just test if the blend operation was working properly.

  



  ffmpeg -i test.mp4 -i logo.png -filter_complex "[0:0] scale=1920x1080 [wm]; [1:0] scale=1920x1080 [prog], [wm][prog] blend=all_mode='overlay':all_opacity=0.7" fart.mp4


  



  I got the error First input link top parameters (size 1920x1080, SAR 1:1) do not match the corresponding second input link bottom parameters (1920x1080, SAR 243:80)
Failed to configure output pad on Parsed_blend_2

  



  So, in addition to the trouble with combining of filters, I'm also having an issue with resizing the watermark as FFMpeg sees it as a different aspect ratio than the other videos.

  



  This is my second day with FFmpeg, so any help would be appreciated.

  



  I'm currently working with FFMpeg version N-61061-gf34cceb