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• How to properly convert RTL subtitles in ffmpeg ?

  25 octobre 2020, par HTMHell

  I'm using the following command to extract subtitles from a video file, and save it as vtt.

  



  ffmpeg -i video.mkv -map 0:s:0 subs.vtt 2>&1


  



  It's working and outputs the subtitles file. The problem is with RTL (right to left) languages (Hebrew, Arabic etc.)
The punctuation are being misplaced.

  



  I will show you an English example of what's happening, for your convenience :

  



  Input text :

  



  Is he alive?
-I don't know.


  



  Output text :

  



  ?Is he alive
.I don't know-


  



  If you want the original text in Hebrew, there it is :

  



  Input Text :

  



  הוא חי?
-אני לא יודע.


  



  Output text :

  



  ?הוא חי
.אני לא יודע-


  



  As you can see, the punctuation marks at the end are going to the start, and vice versa. How can I avoid this behavior ?

  


• How to find what 2 sounds have in common ?

  22 mai 2020, par ThomazPom

  Thank you for your time.

  



  I have a video, with 2 audios tracks (same lenght) (audio1 : en, audio2 : jap).

  



  I try to figure how to export an audio where theses track are identical (blank sound otherwise) or better, the times periods where these have sound in commmon

  



  I think ffmpeg is a good start and i use it occasionally, but this one is a bit too hard for me.

  



  Any ideas ?

  



  Many thanks,
Sorry for my aproximate english.

  



  Thomaz

  



  ->EDIT
Got it with scypi.

  



  from scipy.io.wavfile import read, write
en = read("000001_output_en.wav")
jap = read("000001_output_jp.wav")
out=(en[1]*en[1]==jap[1])
write("output_processed.wav",en[0],out)


  



  to find their common silences :

  



  from scipy.io.wavfile import read, write
en = read("000001_output_en.wav")
jap = read("000001_output_jp.wav")
out=(en[1]*jap[1])
write("output_processed.wav",en[0],out)


  


• Issues grabbing frames from an mp4 video using ffmpeg on java

  31 mars 2015, par TamirW

  I am trying to grab a few frames from an mp4 video files using the ffmpeg library (java). Code snippet below.
  The issues I’m facing are :

  • In some (but not all) the videos I’m testing, I am getting the following warning when grabbing the frames : [swscaler @ 0x7fa642a53600] bad src image pointers
  • Sometimes, the frames I get are just blanks (black), sometimes they contain the last frame in the video (meaning that ALL the frames show the same image). Interestingly, when I’m not getting the above warning, the frames are just fine.

  Any clue or direction about how to debug/solve this issue would be greatly appreciated.

      FFmpegFrameGrabber g = new FFmpegFrameGrabber(video);
  
      List<bufferedimage> frames = new ArrayList<bufferedimage>();
  
      try {
  
          g.start();
  
  
  
          int i = 1, noOfFrames = g.getLengthInFrames();
  
          long FR = Math.round(g.getFrameRate());
  
  
  
          while (i &lt; noOfFrames) {
  
              g.setFrameNumber(i);
  
              IplImage img = g.grab();
  
              BufferedImage bimg = img.getBufferedImage();
  
              frames.add(bimg);
  
  
  
              i += FR;
  
          }
  
  </bufferedimage></bufferedimage>