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• FFmpeg drawtext over multiple lines

  22 novembre 2015, par Jared Glass

  I have the code :

  import subprocess , os
  
  
  
  ffmpeg = "C:\\ffmpeg_10_6_11.exe"
  
  inVid = "C:\\test_in.avi"
  
  outVid = "C:\\test_out.avi"
  
  
  
  if os.path.exists( outVid ):
  
  os.remove( outVid )
  
  proc = subprocess.Popen(ffmpeg + " -i " + inVid + ''' -vf drawtext=fontfile=/Windows/Fonts/arial.ttf:text="onLine1 onLine2 onLine3":fontcolor=white:fontsize=20 -y ''' + outVid , shell=True, stderr=subprocess.PIPE)
  
  proc.wait()
  
  print proc.stderr.read()
  
  os.startfile( outVid )

  to write text to a video file. But I want to write out many lines of text instead of just having it all on the one line.

  Pls help. Thanks

• Playing With File

  8 septembre 2011, par Multimedia Mike — General

  I played with the ‘file’ utility a long time ago because I wanted to make it recognize a large number of multimedia formats. I had trouble getting my changes to take. But I’m prepared to try again after many years.

  Aiming at the Corpus
  In my local mirror of the MPlayerHQ samples archive, I find 9853 unique files. So I run all of them through the ‘file’ command :

    ’find /path/to/samples -type f -print0 | xargs -0 file —no-pad’
  

  My Ubuntu installation has file v5.04. I also tested against 5.07 and the latest, 5.08. Here is the number of files each version was unable to identify (generically marking as ‘data’) :

  5.04  1521
  5.07  1405
  5.08  1501
  

  That seems like a regression for v5.08 until I dug into the details and saw quite a few items like this, indicating that the MPEG detection could use some work :

  
   mov/mov-demux-infinite-loop.mpg : DOS-executable (
  +mov/mg-‹demux-infinite-loop.mpg : data
  
   image-samples/UNeedQT4.pntg : DOS-executable (
  +imY- samples/UNeedQT4.pntg : data
  

  Workflow
  These are just notes to myself and perhaps anyone else who wants to add new file formats to be identified by the ‘file’ command.

  First, download either the latest release from the FTP or clone from Github. Do the usual unpack, ‘./configure’, ‘make’ routine. To use this newly-built version and its associated magic file :

    ./src/file —magic-file magic/magic.mgc <file>
  

  To add a new format for ID, first, run the foregoing command to ensure that it’s not already identified. Then, check over the files in magic/Magdir and see which one might pertain to what you’re doing (it’s unlikely that your format will merit a new file in this directory). For example, for this round, I modified animation, audio, iff, and riff. Add or modify existing specs based on the copious examples in the directory and by consulting the appropriate man page (‘man 5 magic’).

  Finally, run ‘make’ again which will regenerate the magic file. Invoke the above command again to use the modified magic file.

  Before and After
  On a selection of formats taken from the samples archive (renamed and cut down to a kilobyte because detection typically only relies on the first few bytes), here is the “before” :

  amv :            RIFF (little-endian) data
  armovie :        data
  bbc-dirac :      data
  interplay-mve :  data
  mtv :            data
  nintendo-thp :   data
  nullsoft-video : data
  redcode :        data
  sega-film :      data
  smacker :        data
  trueaudio :      data
  vqa :            IFF data
  wavpack :        data
  wc3-mve :        IFF data
  wtv :            data
  

  And the “after” :

  amv :            RIFF (little-endian) data, AMV
  armovie :        ARMovie
  bbc-dirac :      BBC Dirac Video
  interplay-mve :  Interplay MVE Movie
  mtv :            MTV Multimedia File
  nintendo-thp :   Nintendo THP Multimedia
  nullsoft-video : Nullsoft Video
  redcode :        REDCode Video
  sega-film :      Sega FILM/CPK Multimedia, 320 x 224
  smacker :        RAD Game Tools Smacker Multimedia version 2, 320 x 200, 100 frames
  trueaudio :      True Audio Lossless Audio
  vqa :            IFF data, Westwood Studios VQA Multimedia, 418 video frames, 320 x 200
  wavpack :        WavPack Lossless Audio
  wc3-mve :        IFF data, Wing Commander III Video, PC version
  wtv :            Windows Television DVR Media
  

  After rerunning ‘file’ on the mphq corpus using the modified magic file, only 1329 files remain unidentified (down from 1501).

  Going Forward
  As mentioned, MPEG detection could probably be strengthened. However, a major weakness is QuickTime/MP4. Many files are not detected, probably owing to the many ways that QuickTime files can begin.

• Interact with ffmpeg from a .NET program - Write Input

  7 mai 2015, par Shimmy

  In reference to this question, as you can see I managed to run and receive data from the program.

  However I didn’t manage to submit data to it, for instance, while converting a file, pressing q immediately stop conversion and stops the program.
  I need my application to support stopping the process as well, and I think this should be done by passing this parameter to the ffmpeg app, since I want it to take care of all uncollected resource or whatever dust it would leave behind if I would just go and use process.Kill()

  Here is what I’ve tried :

  static int lineCount = 0;
  
  static bool flag;
  
  static void process_ErrorDataReceived(object sender, DataReceivedEventArgs e)
  
  {
  
    Console.WriteLine("Error ({1:m:s:fff}: {0})", lineCount++,
  
        DateTime.Now);
  
  
  
    if (e.Data != null && string.Equals(e.Data,"Press [q] to stop, [?] for help")) 
  
      flag = true;
  
  
  
    if (flag)
  
    {
  
      flag = false;
  
      Console.WriteLine("Stopping ({0:m:s:fff})...", DateTime.Now);
  
      process.CancelErrorRead();
  
      process.CancelOutputRead();
  
      process.StandardInput.WriteLine("q");
  
    }   
  
  
  
    Console.WriteLine(e.Data);
  
    Console.WriteLine();
  
  }

  But it doesn’t do anything, seems that once the conversion has been requested, I have no control on it any more, I can only receive output from it. Running it as stand alone does allow me interaction of course.

  What am I missing here, is it a different trick in submitting the output or the code in previous answer is wrong, or I should have chosen a different approach ?

  For your attention, RedirectStandardInput is on.

  NOTE : as you can see in the answer of my previous question, ffmpeg interacts differently, I think the one who knows the answer will be (maybe I’m wrong) someone with experience in ffmpeg.