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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 ?

  


• iOS switching between audio & subtitle tracks added using ffmpeg

  27 décembre 2019, par Tony M

  Edit : Title altered to reflect that the answer and comments by @llogan cover switching between both audio and subtitle tracks.

  I have an m.mp4 with English audio and want to add a second audio stream in Italian so that I can play either language using the iPhone. When I used this command :

  ffmpeg -i m.mp4 -i ita.mp3 -c copy -map 0 -map 1 out.mp4 

  the output from ffmpeg -i out.mp4 (see below) shows that a new audio stream is added, and I can switch between audio streams using the VLC player. Yet when I transfer the video to the TV app and play it on either MacOS or iOS it only plays the original English and I see no options to play other languages.

  How do I get it to be able to switch between either audio on iOS ?

  Here is the output from ffmpeg -i out.mp4:

      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 400x300 [SAR 1:1 DAR 4:3], q=2-31, 482 kb/s, 23.98 fps, 23.98 tbr, 24k tbn, 24k tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 102 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler
  
      Stream #0:2: Audio: mp3 (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 152 kb/s
  
      Metadata:
  
        encoder         : LAME3.100
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #0:1 -> #0:1 (copy)
  
    Stream #1:0 -> #0:2 (copy)

• Add a 2nd audio stream using ffmpeg so you can switch audio streams on iOS ?

  26 décembre 2019, par Tony M

  I have an m.mp4 with English audio and want to add a second audio stream in Italian so that I can play either language using the iPhone. When I used this command :

  ffmpeg -i m.mp4 -i ita.mp3 -c copy -map 0 -map 1 out.mp4 

  The output from ffmpeg -i out.mp4 (see below) shows that a new audio stream is added, and I can switch between audio streams using the VLC player. Yet when I transfer the video to the TV app and play it on either MacOS or iOS it only plays the original English and I see no options to play other languages.

  How do I get it to be able to switch between either audio on iOS ?

  Here is the output from ffmpeg -i out.mp4:

      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 400x300 [SAR 1:1 DAR 4:3], q=2-31, 482 kb/s, 23.98 fps, 23.98 tbr, 24k tbn, 24k tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 102 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler
  
      Stream #0:2: Audio: mp3 (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 152 kb/s
  
      Metadata:
  
        encoder         : LAME3.100
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #0:1 -> #0:1 (copy)
  
    Stream #1:0 -> #0:2 (copy)