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• ffmpeg filters inserting escape characters in python [duplicate]

  8 mai 2024, par jdauthre

  I am running ffmpeg in python as a subprocess. I want to burn the subtitles into a video. Just using ffmpeg (commandline without python in windows) the following works :

  


  ffmpeg.exe" -y -i  "input_file" -vf "subtitles= \'input_file_path\' :si=0"  -acodec  copy  "output_file_path"


  


  the \ escape characters are required by ffmpeg for special characters within a filter, However trying to replicate this within a python subprocess has proved problematic, here is one of many failed attempts :

  


  command = ["ffmpeg.exe","-y","-i","input_file_path","-acodec","copy","
-vf","subtitles=",'\"'+"input_file_path"+'\"',":si=0",output_file_path]
print(command)
proc = subprocess.Popen(command, stderr=PIPE,stdin=subprocess.PIPE,universal_newlines=True,encoding='utf-8')


  


  I have also tried making a raw string, another attempt :

  


  command = ["ffmpeg.exe","-y","-i","input_file_path","-acodec","copy","
-vf","subtitles=",r'\"'+"input_file_path"+r'\"',":si=0",output_file_path]


  


  this results in an error in ffmpeg, although the syntax looks ok :

  


   Unable to find a suitable output format for '\"input_file_path\"'
\"C:/temp/two.mp4\": Invalid argument


  


  ffmpeg seems to want to treat it as the output.
I need to get the right combination of Python escape characters and ffmpeg escape characters. Any ideas ?

  


• FFmpeg chokes on filenames inside of quotes w/ whitespaces [duplicate]

  18 février 2016, par user3578907

  This question already has an answer here :

  • Script fails with spaces in directory names
    
    1 answer
    

  I’m trying to convert all of my FLACs in to MP3s. Each artist has a folder, and each album has a subfolder. I used the find command to compile a clean list of all of the FLACs in to a file called songlist, and tried dumping it in to FFmpeg with

  (for SONG in `cat songlist` ; do ffmpeg -i "$SONG" -f mp3 -ab 256000 "`basename "$SONG" .flac`.mp3" || break; done)

  Any time ffmpeg reaches a file with a space or special character it interprets it directly. I don’t understand why, as I thought the quotes around $SONG would sanitize it enough. Any thoughts on how to accomplish this task more efficiently or how to fix my code are welcomed.

  songlist is just filled with full paths to the files. No quotes around the paths.

• Playing RTSP in WPF application with low latency using FFMPEG / FFMediaElement (FFME)

  22 mars 2019, par Paboka

  I’m trying to use FFMediaElement (FFME, WPF MediaElement replacement based on FFmpeg) component to play RSTP live video in my WPF application.

  I have a good connection to my camera and I want to play it with minimum available latency.

  I’ve reduced the latency by changing ProbeSize to its minimal value :

  private void Media_OnMediaInitializing(object Sender, MediaInitializingRoutedEventArgs e)
  
  {
  
    e.Configuration.GlobalOptions.ProbeSize = 32;
  
  }

  But I still have about 1 second of latency since the very beginning of the stream. I mean, when I start playing, I have to wait for 1 second till the video appears and then I have 1s of latency.

  I’ve also tried to change following parameters :

  e.Configuration.GlobalOptions.EnableReducedBuffering = true;
  
  e.Configuration.GlobalOptions.FlagNoBuffer = true;
  
  e.Configuration.GlobalOptions.MaxAnalyzeDuration = TimeSpan.Zero;

  but it gave no result.

  I measured time-interval between FFmpeg output lines (the number in the first column is the time, elapsed from the previous line, ms)

   ----     OpenCommand: Entered
  
     39     FFInterop.Initialize: FFmpeg v4.0
  
      0     EVENT START: MediaInitializing
  
      0     EVENT DONE : MediaInitializing
  
    379     EVENT START: MediaOpening
  
      0     EVENT DONE : MediaOpening
  
      0     COMP VIDEO: Start Offset:      0,000; Duration:        N/A
  
     41     SYNC-BUFFER: Started.
  
    609     SYNC-BUFFER: Finished. Clock set to 1534932751,634
  
      0     EVENT START: MediaOpened
  
      0     EVENT DONE : MediaOpened
  
      0     EVENT START: BufferingStarted
  
      0     EVENT DONE : BufferingStarted
  
      0     OpenCommand: Completed
  
      0     V BLK: 1534932751,634 | CLK: 1534932751,634 | DFT:    0 | IX:   0 | PQ:     0,0k | TQ:     0,0k
  
      0     Command Queue (1 commands): Before ProcessNext
  
      0        Play - ID: 404 Canceled: False; Completed: False; Status: WaitingForActivation; State: 
  
     94     V BLK: 1534932751,675 | CLK: 1534932751,699 | DFT:   24 | IX:   1 | PQ:     0,0k | TQ:     0,0k

  So, the most the process of "sync-buffering" takes the most of the time.

  Is there any parameter of FFmpeg which allows reducing a size of the buffer ?