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• ffmpeg crop detect python using subprocess

  12 mai 2015, par JRM

  I want to use python subprocess to call ffmpeg and use crop detect to find all black in a video. The crop detect return I want to put into a string variable and put in a database. At the moment I can get the process running in terminal and but I am unsure about how to grab the specific part of the terminal (stdout) output :

  the script :

  def cropDetect():
  
      p = subprocess.Popen(["ffmpeg", "-i", "/Desktop/ffprobe_instance/Crop_detect/video_file.mpg", "-vf", "cropdetect=24:16:0", "-vframes", "10", "dummy.mp4"], stdout=subprocess.PIPE)
  
      result = p.communicate()[0]
  
      print result
  
  
  
  
  
  # SCRIPT
  
  cropDetect()

  Result in terminal :
  [Parsed_cropdetect_0 @ 0x7fa1d840cb80] x1:719 x2:0 y1:575 y2:0 w :-704 h :-560 x:714 y:570 pos:432142 pts:44102 t:0.490022 crop=-704 :-560:714:570

  How do I take "crop=-704 :-560:714:570" and put it into a variable that I can store in a database ?

  As per update :

  def cropDetect1():
  
      p = subprocess.check_output(["ffmpeg", "-i", "/Desktop/ffprobe_instance/Crop_detect/video_file.mpg", "-vf", "cropdetect=24:16:0", "-vframes", "10", "dummy.mp4"])
  
      match = re.search("crop\S+", p)
  
      crop_result = None
  
      if match is not None:
  
          crop_result = match.group()
  
          print "hello %s" % crop_result

  I can’t seem to print out the "crop_result" - I am presuming that means that the variable is empty ?

  UPDATE : Found it :

  def detectCropFile(localPath):
  
      fpath = "/xxx/xx/Desktop/Crop_detect/videos/USUV.mp4"
  
      print "File to detect crop: %s " % fpath
  
      p = subprocess.Popen(["ffmpeg", "-i", fpath, "-vf", "cropdetect=24:16:0", "-vframes", "500", "-f", "rawvideo", "-y", "/dev/null"], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
  
      infos = p.stderr.read()
  
      print infos
  
      allCrops = re.findall(CROP_DETECT_LINE + ".*", infos)
  
      print allCrops 
  
      mostCommonCrop = Counter(allCrops).most_common(1)
  
      print "most common crop: %s" % mostCommonCrop
  
      print mostCommonCrop[0][0]
  
      global crop
  
      crop = mostCommonCrop[0][0]
  
      video_rename()

  Use : p = subprocess.Popen(["ffmpeg", "-i", fpath, "-vf", "cropdetect=24:16:0", "-vframes", "500", "-f", "rawvideo", "-y", "/dev/null"], stdout=subprocess.PIPE, stderr=subprocess.PIPE) to pipe it out

• Anomalie #2302 : Problème d’affichage des tableaux longs

  9 mai 2012, par cedric -

  Avec le tableau c’est la règle tableaux-middle : match : "/([^|])(\n[|].*[|]\n)([^|])/UmsS" replace : replace_tableaux is_callback : Y qui renvoie un null et vide tout le texte. Sans doute un problème de mémoire à investiguer.

• When streaming with ffmpeg, insert audio only if the source file/stream has no audio

  1er octobre 2020, par Dan Pisarski

  I would like to use the same command, regardless of if my source file, or source stream, has an audio track or has no track at all. I then want ffmpeg to transcode the audio - using either the audio source (if present), or silence (which I see various various ffmpeg audio filters can generate) only if no source audio track is present.

  


  Could someone give an example or some pointers on the right command for this ? Some way to do this with map or similar switches ?

  


  Note here I truly mean no audio track at all, versus say detecting silence in the source audio track. It is a key to be able to do this in one command versus knowing two discreet commands that would do each variation.