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• FFMPEG Extract subtitles at webvtt format while keep position on the screen

  30 septembre 2020, par Maxou

  i'm working on a project where I need to extract subtitles from video files and convert it to WEBVTT format. But when I extract and convert it with FFMPEG my webvtt files doesn't keep the position.

  


  What I want

  


  00:00:11.000 --> 00:00:13.000 align:start


  


  What I get

  


  00:00:11.000 --> 00:00:13.000


  


  While when I test to extract at .ass files the position of the subtitles is keep.

  


  To extract I use this command

  


  ffmpeg -i {filename} -map 0:s:0 -muxdelay 0 -f webvtt subtitles.vtt


  


  Thanks in advance

  


• Extract (demux) subtitles using avcodec_decode_subtitle2 (FFmpeg)

  30 janvier 2020, par user155

  I found some code, edited it a little bit to print text of subtitles, but I’m not sure how to save subtitles to file (extract from video file, e.g. mkv)

  next code just prints a lot of lines, not all of them contains subtitle text

  std::ofstream out ("/path/to/extracted/subtitles.srt");
  
  
  
  while(av_read_frame(pFormatCtx, &pkt) == 0) {
  
      int got_frame = 0;
  
      int ret = avcodec_decode_subtitle2(aCodecCtx, subtitle, &got_frame, &pkt);
  
      if (ret >= 0 && got_frame) {
  
          AVSubtitleRect **rects = subtitle->rects;
  
          for (i = 0; i < subtitle->num_rects; i++) {
  
              AVSubtitleRect rect = *rects[i];
  
              if (rect.type == SUBTITLE_ASS) {
  
                  printf("ASS %s", rect.ass);
  
              } else if (rect.x == SUBTITLE_TEXT) {;
  
                  printf("TEXT %s", rect.text);
  
              }
  
          }
  
          // it just writes some big file (similar to videofile size)
  
          //out.write((char*)pkt.data, pkt.size);
  
      }
  
  }
  
  out.close();
  
  //... 

• Convert .avi to .gif with ffmpeg with good quality AND subtitles

  1er décembre 2015, par Stergios Marias

  I want to use ffmpeg to convert .avi to .gif with good quality and subtitles.

  Now, I use this script to convert from .avi to .gif with good quality :

  ffmpeg -v warning -ss 10:00 -t 5 -i input.avi -vf "fps=15,scale=420:-1:flags=lanczos,palettegen" -y palette.png
  
  ffmpeg -v warning -ss 10:00 -t 5 -i input.avi -i palette.png -lavfi "fps=15,scale=420:-1:flags=lanczos [x]; [x][1:v] paletteuse" -y output.gif

  I generate a palette and then using it to output the gif.

  Then I am using this script to add subtitles to gif :

  ffmpeg -v warning -i output.gif -vf "ass=subtitles.ass" -y outputWithSubs.gif

  All that works just fine. The problem is that the first script gives me good quality without subtitles and the second gives me subtitles without good quality.

  When I am trying to combine them with this script :

  ffmpeg -v warning -ss 10:00 -t 5 -i input.avi -vf "fps=15,scale=420:-1:flags=lanczos,palettegen" -y palette.png
  
  ffmpeg -v warning -ss 10:00 -t 5 -i input.avi -i palette.png -vf "ass=subtitles.ass" -lavfi "fps=15,scale=420:-1:flags=lanczos [x]; [x][1:v] paletteuse" -y output.gif

  I am getting this error :

  Filtergraph 'ass=subtitles.ass' was specified through the -vf/-af/-filter option for output stream 0:0, which is fed from a complex filtergraph.
-vf/-af/-filter and -filter_complex cannot be used together for the same stream.

  Is there any way that I could combine good quality and subtitles at the same time ?