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• Subprocess doesn't return expected result

  8 avril 2023, par Gren Man

  Subprocess doesn't return expected result

  


  I have been trying getting info from video files using ffprobe

  


  But I stumbled upon unexpected results, here are some test I've done

  


  First test

  


  # ffprobe -v error -select_streams v:0 -show_entries stream=height,width -of csv=s=x:p=0 
proc = subprocess.Popen(['ffprobe', '-v', 'error', '-select_streams', 'v:0', '-show_entries', 
       'stream=height,width', '-of', 'csv=s=x:p=0 ', video_path],
       stdout=subprocess.PIPE, stdin=subprocess.PIPE)

# proc.stdout.read() Returns  b'widthXheightt\r\n'
v_resolution = proc.stdout.read().decode('utf-8').replace('\r', '').replace('\n', '')
# Result 'widthXheight'


  


  First test was successful.

  


  Second test

  


  # ffprobe -v error -select_streams v:0 -show_entries stream=display_aspect_ratio -of default=noprint_wrappers=1:nokey=1
proc = subprocess.Popen(['ffprobe', '-v', 'error', '-select_streams', 'v:0', '-show_entries',
       'stream=display_aspect_ratio','-of default=noprint_wrappers=1:nokey=1', video_path],
       stdout=subprocess.PIPE, stdin=subprocess.PIPE)

# proc.stdout.read() Returns b''
a_r = proc.stdout.read().decode('utf-8').replace('\r', '').replace('\n', '')
# Result ''


  


  Hmm, this doesn't sounds right I thought result should be e.g. 16:9

  


  I tried putting code to CMD which returned aforementioned result

  


  Third test

  


  # ffprobe -v error -select_streams v -of default=noprint_wrappers=1:nokey=1 -show_entries stream=r_frame_rate
proc = subprocess.Popen(['ffprobe', '-v', 'error', '-select_streams', 'v', '-of',
       'default=noprint_wrappers=1:nokey=1','-show_entries', 'stream=r_frame_rate',
       video_path], stdout=subprocess.PIPE, stdin=subprocess.PIPE)

# proc.stdout.read() Returns b'30/1'
fps = proc.stdout.read().decode('utf-8').replace('\r', '').replace('\n', '') + ' fps'
# Result 30/1 fps


  


  Just as expected this returned subarashi result

  


  But what happened in a second test ? Can somebody explain it to me ? I used stderr which returned :

  


  Failed to set value 'foo.mp4' for option 'of default=noprint_wrappers=1:nokey=1': Option not found


  


  Result of python code

  


  

  


• Cannot find installation of real FFmpeg (which comes with ffprobe)

  29 mars 2023, par Asm Goni

  I was trying to fit a generator into a model and I got this error : 
AssertionError: Cannot find installation of real FFmpeg (which comes with ffprobe).

  



  I have looked over many of the solutions on GitHub and other questions on Stack Overflow but none of them worked for me.

  



  Here is one of the commands I ran :

  



  sudo add-apt-repository ppa:mc3man/trusty-media  
sudo apt-get update  
sudo apt-get install ffmpeg  
sudo apt-get install frei0r-plugins  


  



  pip list also indicates the presence of ffmpeg-1.4

  



  In addition, I tried force reinstalling and updating ffmpeg just in case any dependencies were not installed properly.

  



  I also set the skvideo's path for ffmpeg manually :

  



  skvideo.setFFmpegPath('/usr/local/lib/python3.6/dist-packages/ffmpeg/')


  



  This returns : /usr/local/lib/python3.6/dist-packages/skvideo/__init__.py:306: UserWarning: ffmpeg/ffprobe not found in path: /usr/local/lib/python3.6/dist-packages/ffmpeg/
  warnings.warn("ffmpeg/ffprobe not found in path: " + str(path), UserWarning)

  



  By the way, when I try installing, it also returns this error, I don't know what to do about this :

  



  Get:127 http://archive.ubuntu.com/ubuntu bionic/main amd64 vdpau-driver-all amd64 1.1.1-3ubuntu1 [4,674 B]
Fetched 60.4 MB in 7s (8,769 kB/s)
E: Failed to fetch http://security.ubuntu.com/ubuntu/pool/main/w/wavpack/libwavpack1_5.1.0-2ubuntu1.1_amd64.deb  404  Not Found [IP: 91.189.88.149 80]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?


  



  I ran apt-get update --fix-missing and that didn't make anything better.

  



  Is there a solution to this ?

  


• FFmpeg error - "at least one output file must be specified" [closed]

  1er février 2018, par Derrick Tucker

  ffmpeg -ss 0 -i rawvid.flv -t 33 -vf scale=640x480 -b:21504 test.mpg

  When run, this returns "At least one output file must be specified", what am I missing ?

  PS : FFmpeg works fine, and if I remove all of the flags in the statement above, it works.