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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

  


  

  


• change brew install directory

  23 juin 2018, par Addison Wu

  I used homebrew to install ffmpeg and it’s by default in /usr/local/Cellar.
  I have to run a matlab code, which tries to read ffmpeg from /usr/local/bin and returns error.

  Is there any way for me to change the path for brew install of ffmpeg ?

• conversion from mp3 to ogg using php

  9 janvier 2014, par Preethy

  I want to convert mp3 file to ogg. I tried the following code

  exec("/usr/local/bin/ffmpeg -i 1.mp4 -vcodec libtheora -acodec libvorbis testjohn4545454.ogg",$output);
  
  var_dump($output);

  But it does not convert the file and it only returns array(0) { }
  and it only takes a little execution time.

  But the conversion is success when using ssh command.

  Please give me solution.